,,longmans' ,,civil ,,engineering ,,series ,,railway ,,construction ,,longmans' ,,civil ,,engineering ,,series ,,notes ,,on ,,docks ,,and ,,dock ,,construction4 ,by ,c4 ,,colson1 ,c4,b41 ,m4,inst4,c4,e41 ,deputy ,civil ,engineer-in-,chief1 ,loan ,works1 ,admiralty4 ,with #cfe ,illustrations4 ,medium #hvo1 #bas4 net4 ,,calculations ,,in ,,hydraulic ,,engineering3 ,a ,practical ,text-,book for the ,use of ,students1 ,draughtsmen1 and ,engineers4 ,by ,t4 ,,claxton ,,fidler1 ,m4,i4,c4,e41 ,professor of ,engineering1 ,university ,college1 ,dundee4 ,part ,i4 ,fluid ,pressure and the ,calculation of its ,effects in ,engineering ,structures4 ,with numerous ,illustrations and ,examples4 ,medium #hvo1 #fs4 #f;d4 net4 ,part ,,ii4 ,calculations in ,hydro-,kinetics4 ,with numerous ,illustrations and ,examples4 ,medium #hvo1 #gs4 #f;d4 net4 ,,notes ,,on ,,construction ,,in ,,mild ,,steel3 ,arranged for the ,use of ,junior ,draughtsmen in the ,architectural and ,engineering ,professions4 ,with #dbe ,illustrations from ,working ,drawings1 ,diagrams and ,tables4 ,by ,,henry ,,fidler1 ,m4,i4,c4,e4 ,medium #hvo1 #afs4 net4 ,,railway ,,construction4 ,by ,w4 ,h4 ,,mills1 ,m4,i4,c4,e41 ,engineer-in-,chief1 ,great ,northern ,railway of ,ireland4 ,with #eaf ,illustrations4 ,medium #hvo1 #ahs4 net4 ,,principles ,,and ,,practice ,,of ,,harbour ,,construction4 ,by ,,william ,,shield1 ,f4,r4,s4,e41 ,m4,inst4,c4,e41 and ,executive ,engineer1 ,national ,harbour of ,refuge1 ,peterhead1 ,n4,b4 ,with #ig ,illustrations4 ,medium #hvo1 #aes4 net4 ,,civil ,,engineering ,,as ,,applied ,,in ,,construction4 ,by ,,leveson ,,francis ,,vernon-,,harcourt1 ,m4,a41 ,m4,inst4,c4,e4 ,with #cfh ,illustrations4 ,medium #hvo1 #ads4 net4 ,,sanitary ,,engineering ,,with ,,respect ,,to ,,water-,,supply ,,and ,,sewage ,,disposal4 ,by ,,leveson ,,francis ,,vernon-,,harcourt1 ,m4,a41 ,m4,inst4,c4,e4 ,with #bhg ,illustrations4 ,medium #hvo1 #ads4 net4 ,,tidal ,,rivers3 their 7#a7 ,hydraulics1 7#b7 ,improvement1 7#c7 ,navigation4 ,by ,w4 ,h4 ,,wheeler1 ,m4,inst4,c4,e4 ,with #ge ,illustrations4 ,medium #hvo1 #afs4 net4 ,,longmans1 ,,green1 ,,and ,,co4 ,,london1 ,,new ,,york1 ,,bombay1 ,,and ,,calcutta ,illustration3 ,frontispiece4 ,,kinsua ,,viaduct1 ,,erie ,,railway1 ,u4,s4,a4 ,see p4 #ig4 ,,longmans' ,,civil ,,engineering ,,series ,,railway ,,construction ,,by ,,william ,,hemingway ,,mills1 ,m4,,inst4,c4,e4 ,,past ,,president ,,of ,,the ,,institution ,,of ,,civil ,,engineers ,,of ,,ireland1 ,,and ,,engineer-,,in-,,chief ,,of ,,the ,,great ,,northern ,,railway ,,of ,,ireland ,illustration ,,with ,,illustrations ,,fourth ,,impression ,,longmans1 ,,green1 ,,and ,,co4 #ci ,,paternoster ,,row1 ,,london ,,new ,,york1 ,,bombay1 ,,and ,,calcutta #aiaj ,all rights reserved ,,preface ,the construction and maintenance of a railway calls for the application of so many branches of engineering that several volumes would be required to do ample justice to a subject so comprehensive and ever-extending4 ,to avoid attempting so wide a range1 the object of the following pages has been to describe briefly some of the recognized leading features which regulate railway construction1 and to assist the explanation with sketches of works selected from actual practice4 ,where the number of existing good examples is legion1 it is somewhat difficult to make a choice for illustration1 and the course adopted has been to select such samples of structures as appear best to elucidate in a simple manner the different types of work under consideration4 ,in the drawings and diagrams many important minor details are necessarily omitted1 partly to avoid complexity1 but principally to leave more prominent the leading features of the particular piece of work referred to in the description4 ,some of the sketches of the large span bridges and large span roofs are only shown in outline2 but1 as their principal dimensions are given1 a general idea can be obtained of their actual proportions4 ,no allusion is made to the requisite strengths of the various structures described1 nor to the necessary dimensions of the materials used in their construction1 as this would necessitate the introduction of a vast amount of mathematical formul which does not come under the province of the object in view1 and which the engineer has already at command from his training and works of reference4 ,neither is any mention made as to the probable cost of the different works of construction1 as these must always vary to a very large extent1 according to the locality1 facility of supply1 and current prices of materials4 ,every railway scheme which is the outcome of public enterprise has its commercial aspect and influence4 ,the large sums to be invested in its construction are expected to yield permanent and increasing returns1 and this desirable end can only be attained where there is thorough efficiency in works and equipment1 and a full compliance with those national regulations which control matters connected with public safety4 ,the correct dealing with the technical requirements and structural features of the undertaking must always precede all other considerations1 as the constituted authorities will exact a proper fulfilment of all the statutory obligations1 regardless of the prospective remuneration to the promoters4 ,a stroke of the pen may change a train-service1 or alter the rates and tariffs1 but a modification in the works of construction arising out of errors or oversight1 would entail a heavy expenditure and tedious delay4 ,the essential point of every railway undertaking must be its suitability and completeness in every respect for the duty for which it is intended4 ,notes of what has been done are always valuable for consideration and comparison1 and that the following brief description and sketches may be found useful for reference1 is the earnest wish of the writer4 ,w4 ,h4 ,,mills1 ,m4,,inst4,c4,e4 ,,contents ,,chapter ,i4 ,,page ,location of a line of railway--,government regulations--,questions for consideration in connection with gauge1 gradients1 and curves #a ,,chapter ,,ii4 ,works of construction3 ,earthworks1 ,culverts1 ,bridges1 ,foundations1 ,screw piles1 ,cylinders1 ,caissons1 ,retaining walls1 and ,tunnels #fj ,,chapter ,,iii4 ,permanent way--,rails--,sleepers--,fastenings--and ,permanent-way laying #ahb ,,chapter ,,iv4 ,stations3 ,station ,buildings1 ,roofs1 ,lines1 and ,sidings #bdh ,,chapter ,v4 ,sorting-sidings--,turn-tables--,travers ers--,water-,tanks and ,water-,columns #bhe ,,chapter ,,vi4 ,comparative ,weights of some ,types of ,modern ,locomotives #cjd ,,chapter ,,vii4 ,signals--,interlocking--,block ,telegraph and ,electric ,train ,staff ,instruments #cac ,,chapter ,,viii4 ,railways of different ranks--,progressive improvements--,growing tendency for increased speeds1 with corresponding increase in weight of permanent way and rolling-stock--,electricity as a motive-power #cdh ,,index #cfa ,,chapter ,i4 #a ,location of a line of railway--,government regulations--,questions for consideration in connection with gauge1 gradients1 and curves4 ,location4--,the locating of a line of railway1 or the determination of its exact route1 is influenced by many circumstances4 ,in a rich country1 with thickly populated districts and large industrial enterprises1 there are towns to be served1 manufacturing centres to be accommodated1 and harbours to be brought into connection2 while1 at the same time1 there may be important estates which must be avoided and private properties which must not be entered4 ,each point will present its own individual claim for consideration when selecting the route which promises the greatest amount of public convenience and commercial success4 ,in new countries--in our colonies1 and especially out in the far west of ,canada and the ,united ,states--railways have to be laid out in almost uninhabited districts1 where there is but little population or commerce to serve1 and where the principal object is to obtain the best and most direct route through the vast territories1 leaving colonists and settlers to choose afterwards the most convenient sites for towns and villages4 ,untrammelled by the network of public and private roads and properties which are met with at home1 it might appear that the locating of such a line would be comparatively light2 but even in such countries1 which at first sight seem to present unlimited freedom for selecting a route1 much can be done1 and should be done1 by taking a course through those plains and districts which possess the best natural resources for future agricultural1 manufacturing1 or mineral development4 ,in addition to the motives of convenience and policy1 the route of every line of railway must be influenced by the natural features of the country--the mountains1 valleys1 and rivers4 ,these physical obstacles are in some cases on such an enormous scale as to compel #b long detours in the formation of a more suitable opening2 and in others1 although the difficulties are not insurmountable1 they may involve works of great magnitude and expense4 ,in a comparatively rich country1 with a prospect of large and remunerative traffic1 a succession of heavy works1 bridges1 and tunnels may be admissible and expedient2 but in new countries economy of outlay has to be considered1 and costly works avoided as much as possible4 ,every one of the heavy works on a line1 whether lofty bridges1 long viaducts1 or costly tunnels1 not only enormously increase the original expenditure of the undertaking1 but also entail large annual outlay in the necessary constant supervision and maintenance4 ,each particular scheme will have to be discussed on its own individual merits4 ,the heavy1 high-speed passenger traffic line will suggest light gradients and easy curves1 while on secondary lines and in thinly populated districts it may be prudent1 for the sake of economy1 to introduce sharper curves and heavier gradients4 ,even in the latter case1 and especially in new countries1 it is well to keep in view the future possibilities of the undertaking4 ,the steeper the gradients1 the greater the cost and time in working the traffic1 and if there is every probability of early and large development1 the prospective increase may warrant an additional outlay in the original construction4 ,large1 open plains and wide valleys of important rivers generally afford ample latitude for the selection of a suitable route1 and1 by taking advantage of the gradations of altitude1 a favourable course may be adopted without incurring excessive gradients4 ,when traversing moderately hilly districts1 some low ridge or opening may be found1 which may form a pass from the one side to the other1 and the line may be laid out for a long distance to lead gradually up to the highest point4 ,but when a route has to be laid out over some of those lofty mountain ranges which are met with abroad1 the locating of a suitable line1 or of any line1 becomes particularly intricate and difficult4 ,a comparatively low ridge may be found possessing features in favour of the project1 but the question will be how to reach that point4 ,the nearer the summit of these high mountains1 the more precipitous the sides2 no one slope can be found sufficiently long and uniform to #c permit a practical direct ascent1 and the only way out of the difficulty is to make a series of detours along the various spurs of the mountains to gain length to overcome the height4 ,each detour has to be the subject of most careful study4 ,forming part of a long series of ascending gradients1 it has to follow the winding of the mountain-side1 must be laid out to be always gaining in height1 and will comprise important works1 many of them of considerable extent1 necessary for protection against the floods and atmospherical changes of the locality4 ,in these higher altitudes nature is met with on the grandest and most rugged scale4 ,deep gorges1 wide ravines1 and almost perpendicular rocks form the pathway along which the line must be carried1 and the skill of the engineer is taxed to the utmost to select a course which shall comprise a minimum of the works of magnitude4 ,mile after mile of line must be laid out in almost inaccessible places1 loose or broken rocks must be avoided1 a firm foundation must be obtained at all points skirting high ledges1 and ample provision must be made for those mountain torrents which rise so suddenly1 and are liable to sweep away all before them4 ,many grand examples of these detour lines are in existence in different parts of the world1 and the traveller passing over them can realize the difficulties that had to be encountered1 and the masterly manner in which they have been overcome4 ,before proceeding to carry out the works of any line of railway1 it is necessary to prepare a complete plan and section of the line1 showing the route to be followed and the position of the various curves1 gradients1 and principal works4 ,within certain limits1 the course of the line may have to be slightly modified as the work proceeds1 in consequence of ground turning out unfavourable1 river-crossings treacherous1 or of sites involving so many contingent alterations that it is found better to avoid them altogether4 ,the route should1 however1 be so carefully studied out before completing the final plan and section1 as to leave only minor deviations of line and level to be dealt with in the actual carrying out of the work4 ,the promoters of lines in the ,united ,kingdom obtain valuable assistance from the ordnance maps1 which give full and reliable information regarding the position of all roads1 rivers1 and boundaries of counties1 parishes1 and townlands4 ,in many parts abroad #d local maps are scarce1 and not always accurate1 and engineers have to depend principally on their own surveys1 and rely upon the resident local authorities for any particulars as to divisions of territory4 ,on some of our great colonial plains1 and out in the far west of ,america1 a line may be laid out for miles without a single landmark to localize it on a plan2 but careful setting out1 and the relative levels of the ground and gradients1 as shown on the section1 will always indicate the correct position of any portion of the work4 ,both at home and abroad complete plans and sections of any proposed railway must be deposited with the proper ,government authorities1 and must be approved and sanctioned by them before permission can be obtained to proceed with the works4 ,the regulations regarding the scale and general arrangement of these plans and sections vary in different countries1 and are subject to modification from time to time4 ,each country has its own special enactments relative to the method of dealing with roads1 rivers1 streams1 and public and private property proposed to be interfered with in the construction of any line1 and a knowledge of these is absolutely necessary for the promoters of any new scheme1 inasmuch as some of the requirements may1 in certain instances1 influence the precise route to be selected4 ,the ,english ,government has passed several ,acts of ,parliament setting forth the general conditions which must be complied with in the construction of any railway in the ,united ,kingdom4 ,these conditions1 or standing orders1 relate both to the acquirement of land and property1 the size and description of works for public or private accommodation1 and the inspection and official approval of the undertaking when completed4 ,these fixed regulations are alike valuable to the promoters and to the public2 the former are informed of the principal points with which the scheme must conform1 and the latter know the limit of their legal demands4 ,no line of railway1 or extension of any railway1 will obtain ,parliamentary sanction unless it can be satisfactorily proved in the outset1 that its construction would be of public advantage4 ,this point is of paramount importance1 and due weight must be given to it when preparing to refute the evidence of opponents to the scheme4 ,illustration3 ,fig4 #a4 ,when conceding the right to make any railway1 ,parliament grants with #f it the power to purchase lands or property compulsorily1 or by agreement1 to change and divert roads and streams in the manner shown on the deposited plans1 and to construct all necessary bridges and works in accordance with the standing orders1 or such modifications of them as may be approved by the ,board of ,trade4 ,the standing orders1 or ,government regulations1 are very comprehensive1 and include much detailed information on all questions likely to arise4 ,the following brief summary of some of the principal orders relating to deposited plans1 and works of construction1 will be found useful for reference4 ,extract from ,government ,standing ,orders and ,regulations4--,all plans and sections relative to proposed new railways must be lodged with the constituted ,government ,authorities on or before ,november #cj4 ,every deposited plan must be drawn to a scale of not less than four inches to a mile1 and must describe the centre line1 or situation of the work 7no alternative line being allowed71 and must show all lands1 gardens1 or buildings within the limits of deviation1 each one being numbered with a reference number1 and where powers to make lateral deviations are applied for1 the limits of such deviation must be marked on the plan4 ,unless the whole of such plan be drawn to a scale of not less than #djj feet to an inch1 an enlarged plan must be drawn to that scale of every building and garden within the limits of deviation4 ,the ,railway ,clauses ,act limits the extent of deviation to #ajj yards on each side of the centre line in the country1 and #aj yards on each side of the centre line in towns or villages4 ,the distances must be marked on the plan in miles and furlongs from one of the termini4 ,the radius of every curve not exceeding one mile must be marked on the plan in furlongs and chains4 ,in tunnels the centre line must be dotted1 but no work must be shown as tunnelling1 in the making of which it is necessary to cut through1 or remove the surface soil4 ,if it is intended to divert or alter any public road1 navigable river1 canal1 or railway1 the course and extent of such diversion1 etc41 shall be marked on the plan4 ,illustration3 ,fig4 #b4 ,when a railway is to form a junction with an existing railway1 the #h course of such existing railway must be shown on the plan for a distance of #hjj yards on each side of the proposed junction4 ,in the case of ,bills for constructing subways1 the plans and sections must indicate the height and width of such subway1 and the nature of the approaches by which it is proposed to afford access to such subway4 ,the ,book of ,reference must contain the names of all owners1 lessees1 and occupiers of all lands and houses of every parish within the limits of deviation4 ,the numbers on the ,book of ,reference must correspond with the numbers on the plan1 and opposite to each number must be entered a brief description of the property1 whether field1 garden1 house1 road1 railway1 or river4 ,it is intended that the plan and ,book of ,reference together1 shall afford ample information to enable all parties interested to ascertain to what extent their property will be affected by the proposed undertaking4 ,the section must be drawn to the same horizontal scale as the plan1 and to a vertical scale of not less than #ajj feet to an inch1 and must show the level of the ground1 the level of the proposed work1 the height of every embankment1 the depth of every cutting1 and a horizontal datum line which shall be referred to some fixed point1 near one of the termini4 ,in every section of a railway1 the line of railway marked thereon must correspond with the upper surface of the rails4 ,distances on the datum line must be marked in miles and furlongs to correspond with those on the plan2 a vertical measure from the datum line to the line of the railway must be marked in feet and decimals at the commencement and termination of the railway1 and at each change of gradient1 and the rate of inclination between such vertical measures must also be marked4 ,wherever the line of railway crosses any public carriage road1 navigable river1 canal1 or railway1 the height of the railway over1 or depth beneath the surface thereof1 and the height and span of every arch by which the railway will be carried over the same1 must be marked in figures4 ,illustration3 ,fig4 #c4 ,in the case of a public road level crossing1 it must be described on the section1 and it must also be stated if such level will be unaltered4 ,if any alteration be intended in the level of any canal1 public road1 or railway which will be crossed by the intended line of railway1 the same must be stated on the section and cross-sections to a horizontal scale of not less than #ccj feet to an inch1 and a vertical #aj scale of not less than #dj feet to an inch must be added1 which must show the present surface of such road1 canal1 etc41 and the intended surface thereof when altered1 and the greatest of the present and intended rates of inclination marked in figures1 such cross-sections to extend #bjj yards on each side of the centre line of railway4 ,wherever the height of any embankment1 or depth of any cutting1 shall exceed #e feet1 the extreme height over or depth beneath the surface of the ground must be marked in figures upon the section4 ,all tunnels and viaducts must be shown on the section4 ,at a junction with an existing railway1 the gradient of such existing railway must be shown on the section on the same scale as the general section for a distance of #hjj yards on each side of the point of junction4 ,where the level of any turnpike or public road has to be altered in making any railway1 the gradient of any altered road need not be better than the mean inclination of the existing road within a distance of #bej yards of the point of crossing the railway2 but where the existing roads have easy gradients1 then the gradients of the altered roads1 whether carried over1 or under1 or on the level with the railway1 must not be steeper than #a in #cj for a turnpike road1 #a in #bj for a public carriage road1 #a in #af for a private or occupation road4 ,a good and sufficient fence1 #d feet high at least1 shall be made on each side of every bridge1 and fences #c feet high on the approaches4 ,the application to cross any public road on the level must be reported upon by one of the officers of the ,board of ,trade1 and special permission for the work must be embodied in the ,act4 ,not more than #bj houses of the labouring classes may be purchased in any city or parish in ,england1 ,scotland1 and ,wales1 or more than #aj such houses in ,ireland1 until approval has been obtained to a scheme for building such houses in lieu thereof as the authorities may deem necessary4 ,every bridge 7unless specially authorized to be otherwise7 must conform with the following regulations3-- ,a bridge over a turnpike road must have a clear span of #ce feet on the square between the abutments1 with a headway1 or height1 of #af feet for a width of #ab feet1 as shown on ,fig4 #ab4 ,illustration3 ,fig4 #d4 ,a bridge over a public road must have a clear span of #be feet on the #ab square between the abutments1 with a headway of #ae feet for a width of #aj feet1 as shown on ,fig4 #ac4 ,a bridge over a private or occupation road must have a clear span of #ab feet on the square between the abutments1 with a headway of #ad feet for a width of #i feet1 as shown on ,fig4 #ad4 ,road bridges over the railway must have the same clear width between the parapets1 measured on the square1 as the widths prescribed for road bridges under the railway1 or #ce feet for a turnpike road1 #be feet for a public road1 and #ab feet for private or occupation road4 ,it is not compulsory1 however1 to construct the public road bridges over or under the railway of a greater width than the average available width of the existing roads within #ej yards of the point of crossing the railway1 but in no case must a bridge have a less width than #bj feet4 ,should the narrow roads be widened at any future time1 the railway company will be under the obligation to widen the bridges at their own expense to the extent of the statutory widths of #ce feet for a turnpike road1 and #be feet for a public road4 ,suitable accommodation works in the form of bridges1 level crossings1 gates1 or other works1 must be provided for the owners1 or occupiers of lands1 or properties intersected or affected by the construction of the railway2 or payments may be made by agreement instead of accommodation works4 ,all questions1 or differences between the ,railway ,company1 and the owners or occupiers of property affected1 will be decided by the authorities duly appointed by the ,government for the purpose4 ,in constructing the railway1 the ,parliamentary plans and sections may be deviated from to the following extent3-- ,the centre line may be deviated anywhere within the limits of deviation 7#ajj yards on each side of the centre line in country1 and #aj yards each side in towns1 or villages74 ,curves may be sharpened up to half a mile radius1 and further1 if authorized by the ,board of ,trade4 ,a tunnel may be made instead of a cutting1 and a viaduct instead of an embankment1 if authorized by the ,board of ,trade4 ,the levels may be deviated from to the extent of #e feet in the country1 and #b feet in a town1 or village1 and various authorities have power to consent to further deviations4 ,illustration3 ,fig4 #e4 ,gradients may be diminished to any extent1 gradients flatter than #a in #ajj may be made steeper to the extent of #aj feet in a mile1 and #ad gradients steeper than #a in #ajj may be made steeper to the extent of #c feet in a mile1 or to such further extent as may be authorized by the ,board of ,trade4 ,suitable fences must be erected on each side of the line1 to separate the land taken for the use of the railway from the adjoining lands not taken1 and to protect such lands from trespass1 or the cattle of the owners1 or occupiers thereof from straying on to the railway4 ,in addition to the ,parliamentary plans1 and sections1 and ,book of ,reference1 an estimate of the cost of each separate line1 or branch1 must be prepared as near to the following form as circumstances will permit4 ,,estimate ,,of ,,the ,,proposed 7,,railway74 ,line ,no4 ---------------------------------------- ------------------------------- ,miles4 ,f4 ,chs4 ,whether single or double4 ,length of ,line3 ---------------------------------------- --------------------------- ,cubic yards4 ,price per s4 d4 s4 d4 yard4 ---------------------------------------- ----- ,earthworks3-- ,cuttings--,rock ,soft soil ,roads ------------------------------------ ,total ------------------------------------ ,embankments1 including roads1 cubic yards ,bridges1 public roads--number ,accommodation bridges and works ,viaducts ,culverts and drains ,metallings of roads and level crossings ,gatekeepers' houses at level crossings ,permanent way1 including fencing3-- ,miles4 ,f4 ,chs4 ,cost per mile4 s4 d4 at ,permanent way for sidings1 and cost of junctions ,stations --------- ,contingencies per cent4 --------- ,a4 ,r4 ,p4 ,land and buildings --------- ,total ,dated this day of #ah ,witness3 ,engineer4 ,illustration3 ,fig4 #f4 ,the same details for each branch1 and general summary of total cost4 #af ,every ,railway ,bill must be read twice1 both in the ,house of ,commons and in the ,house of ,lords4 ,a committee1 duly appointed for each ,house1 must report upon it1 and if the reports from such committees be favourable1 the ,bill will be read a third time1 and passed4 ,when it has passed both ,houses1 the ,bill receives the ,royal ,assent1 and becomes law4 ,the minimum scale of four inches to a mile for the plans is so very small that it is rarely1 if ever1 adopted4 ,it would necessitate enlarged plans of so many portions to show clearly the property or buildings inside the limits of deviation1 that in practice it is found expedient to make the plans to a much larger scale4 ,figs4 #a and #b show a small portion of a ,parliamentary plan and section drawn to the minimum scale allowed1 with an enlargement of a small part to distinguish the houses clearly4 ,figs4 #c and #d show a part of the same plan and section drawn to a scale of #djj feet to an inch1 a scale which is very frequently adopted1 and is sufficiently large to distinguish the buildings and small plots1 except in closely populated districts4 ,this scale also gives ample room for reference numbers4 ,the ,parliamentary plans and sections must be accurate in delineation1 levels1 and description4 ,all property within the prescribed limits of deviation must be clearly shown1 and the numbers and description on the plans and book of reference must be concise and complete1 to enable the owners to ascertain to what extent they will be affected4 ,in every place where it is proposed to interfere with any public highway1 street1 footpath1 river or canal1 the manner of such proposed alteration must be shown and described on both plan and section4 ,the commencement and termination of every tunnel must be correctly indicated1 and the length given on both plan and section4 ,an omission of any of the above requirements might prove very detrimental to the scheme1 and possibly result in the ,bill being thrown out of ,parliament for non-compliance with standing orders4 ,illustration3 ,fig4 #g4 ,in carrying out the works the constructors have power to deviate the centre line either to the one side or the other1 provided that such deviation will permit of the boundary of the works1 or property to be acquired1 to come within the limits of deviation or property #ah referenced1 and they may also vary the levels of the line to the extent prescribed in the standing orders4 ,figs4 #e and #f are parts of a ,parliamentary plan and section showing alteration of a public road with an overline bridge--also a diversion of a small river to avoid two river bridges4 ,figs4 #g and #h are parts of a ,parliamentary plan and section showing a public road diverted and carried under the railway4 ,a stipulated time is fixed in the ,bill for the purchase of the property and construction of the line1 and if this time be exceeded before the completion of the works1 it will be necessary to obtain further ,parliamentary powers for an extension of time4 ,every new railway1 or extension of railway1 in the ,united ,kingdom1 must be inspected1 and certified1 by one of the inspecting officers of the ,board of ,trade1 previous to ,government sanction being granted for its opening as a passenger line4 ,to facilitate these inspections1 and as a guide both to their own inspecting officers and the engineers in charge of the construction1 the ,board of ,trade have issued a list of the principal requirements in connection with all new lines4 ,the following is a copy of the list so far as relates to works of construction and signals3-- ,requirements of the ,board of ,trade4--#a4 ,the requisite apparatus for providing by means of the block telegraph system an adequate interval of space between following trains1 and1 in the case of junctions1 between converging or crossing trains4 ,in the case of single lines worked by one engine under steam 7or two or more coupled together7 carrying a staff1 no such apparatus will be required4 #b4 ,home-signals and distant-signals for each direction to be fixed at stations and junctions1 with extra signals for such dock1 or bay lines1 as are used either for the arrival1 or for the departure of trains1 and starting-signals for each direction1 at all passenger stations which are also block posts4 ,on passenger lines all cross-over roads and all connections for goods1 or mineral lines1 and sidings to be protected by home and distant signals1 and as a rule at all important running junctions a separate distant-signal to be provided in connection with each home-signal4 ,illustration3 ,fig4 #h4 ,signals may be dispensed with on single lines under the following conditions3-- 7a7 ,at all stations and siding connections upon a line worked by #bj one engine only 7or two engines coupled together71 carrying a staff1 and when all points are locked by such staff4 7b7 ,at any intermediate siding connection upon a line worked under the train staff and ticket system1 or under the electric staff or tablet system1 where the points are locked by the staff or tablet4 7c7 ,at intermediate stations1 which are not staff or tablet stations1 upon a line worked under the electric staff or tablet system3 ,sidings1 if any1 being locked as in 7b74 #c4 ,the signals at junctions to be on separate posts1 or on brackets2 and the signals at stations1 when there is more than one arm on one side of a post1 to be made to apply--the first1 or upper arm1 to the line on the left1 the second arm to the line next in order from the left1 and so on2 but in cases where the main1 or more important line1 is not the one on the left1 separate signal-posts to be provided1 or the arms to be on brackets4 ,distant-signals to be distinguished by notches cut out of the ends of the arms1 and to be controlled by home or starting signals for the same direction when on the same post4 ,a distant-signal arm must not be placed above a home or starting signal arm on the same post for trains going in the same direction4 ,in the case of sidings1 a low short arm and a small signal light1 distinguishable from the arms or lights for the passenger lines1 may be employed1 but in such cases disc signals are1 as a rule1 preferable4 ,every signal arm to be so weighted as to fly to and remain at danger on the breaking at any point of the connection between the arm and the lever working it4 #d4 ,on new lines worked independently1 the front signal lights to be green for 8all right10 and red for 8danger20 the back lights 7visible only when the signals are at 8danger07 to be white4 ,this requirement not to be obligatory in the case of new lines run over by trains of other companies using a different system of lights4 #e4 ,facing points to be avoided as far as possible1 but when they cannot be dispensed with they must be placed as near as practicable to the levers by which they are worked or bolted4 ,the limit of distance from levers working points to be #ahj yards in the case of facing points1 and #cjj yards in the case of trailing points on the main line1 or safety points of sidings4 ,illustration3 ,fig4 #i4 ,in order to ensure that the points are in their proper position before #bb the signals are lowered1 and to prevent the signalman from shifting them while a train is passing over them1 all facing points must be fitted with facing-point locks and locking-bars1 and with means for detecting any failure in the connections between the signal-cabin and points4 ,the length of the locking-bars to exceed the greatest wheel-base between any two pairs of wheels of the vehicles in use on the line1 and the stock rails to be tied to gauge with iron or steel ties4 ,all points1 whether facing or trailing1 to be worked or bolted by rods1 and not by wires1 and to be fitted with double connecting-rods4 #f4 ,the levers by which points and signals are worked to be interlocked and1 as a rule1 brought close together1 into the position most convenient for the person working them1 in a signal-cabin or on a properly constructed stage4 ,the signal-cabin to be commodious1 and to be supplied with a clock1 and with a separate block instrument for signalling trains on each line of rails4 ,the point-levers and signal-levers to be so placed in the cabin that the signalman when working them shall have the best possible view of the railway1 and the cabin itself to be so situated as to enable the signalman to see the arms and the lights of the signals and the working of the points4 ,the back lights of the signal lamps to be made as small as possible1 having regard to efficiency1 and when the front lights are visible to the signalman in his cabin no back lights to be provided4 ,the fixed lights in the signal-cabin to be screened off1 so as not to be mistakable for the signals exhibited to control the running of trains4 ,if1 from any unavoidable cause1 the arm and light of any signal cannot be seen by the signalman they must1 as a rule1 be repeated in the cabin4 #g4 ,the interlocking to be so arranged that the signalman shall be unable to lower a signal for the approach of a train until after he has set the points in the proper position for it to pass2 that it shall not be possible for him to exhibit at the same moment any two signals that can lead to a collision between two trains2 and that1 after having lowered the signals to allow a train to pass1 he shall not be able to move any points connected with1 or leading to1 the line on which the train is moving4 ,points also1 if possible1 to be so interlocked as to avoid the risk of a collision4 ,illustration3 ,fig4 #aj4 ,home or starting signals next in advance of trading-points when #bd lowered1 to lock such points in either position1 unless such locking will unduly interfere with the traffic4 ,a distant signal must not be capable of being lowered unless the home and starting signals in advance of it have been lowered4 #h4 ,sidings to be so arranged that shunting operations upon them shall cause the least possible obstruction to the passenger lines4 ,safety-points to be provided upon goods and mineral lines and sidings1 at their junctions with passenger lines1 with the points closed against the passenger lines and interlocked with the signals4 #i4 ,when a junction is situated near to a passenger station1 the platforms to be so arranged as to prevent1 as far as possible1 any necessity for standing trains on the junction4 #aj4 ,the junctions of all single lines to be1 as a rule1 formed as double-line junctions4 #aa4 ,the lines of railway leading to the passenger platforms to be arranged so that the engines shall always be in front of the passenger trains as they arrive at and depart from a station2 and so that1 in the case of double lines1 or of passing places on single lines1 each line shall have its own platform4 ,at terminal stations a double line of railway must not end as a single line4 #ab4 ,platforms to be continuous1 and not less than #f feet wide for stations of small traffic1 nor less than #ab feet wide for important stations4 ,the descents at the ends of the platforms to be by ramps1 and not by steps4 ,pillars for the support of roofs and other fixed works not to be less than #f feet from the edges of the platforms4 ,the height of the platforms above rail level to be #c feet1 save under exceptional circumstances1 and in no case less than #b feet #f inches4 ,the edges of the platforms to overhang not less than #ab inches4 ,as little space as possible to be left between the edges of the platforms and those of the footboards on the carriages4 ,shelter to be provided on every platform1 and conveniences where necessary4 ,names of stations to be shown on boards and on the platform lamps4 #ac4 ,when stations are placed on1 or near a viaduct1 or bridge under the railway1 a parapet or fence on each side to be provided of sufficient height to prevent passengers1 who may by mistake leave the carriages when not at the platform1 from falling from the viaduct or bridge in the dark4 ,illustration3 ,fig4 #aa4 #ad4 ,footbridges or subways to be provided for passengers to cross the #bf railway at all exchange and other important stations4 ,staircases or ramps leading to or from platforms to be at no point narrower than at the top1 and the available width to be in no case contracted by any erection or fixed obstruction whatever below the top4 ,at all stations where crowding may be expected1 the staircases or ramps to be of ample width1 and barriers for regulating the entrance of the crowd at the top to be erected4 ,if in such cases there are gates at the bottom1 a speaking-tube or other means of communication between the top and bottom to be provided2 and in all cases gates at the bottom of a staircase or ramp to open outwards4 ,for closing the openings at the top1 sliding bars or gates are considered best4 ,the steps of staircases to be never less than #aa inches in the tread1 nor more than #g inches in the rise1 and midway landings to be provided where the height exceeds #aj feet4 ,efficient handrails to be provided on both staircases and ramps1 and in subways where ramps are used the inclination not to exceed #a in #h4 #ae4 ,a clock to be provided at every station1 in some conspicuous position visible from the platforms4 #af4 ,no station to be constructed1 and no siding to join a passenger line1 on a steeper gradient than #a in #bfj1 except where it is unavoidable4 ,when the line is double1 and the gradient at a station or siding-junction is necessarily steeper than #a in #bfj1 and when danger is to be apprehended from vehicles running back1 a catch-siding with points weighted for the siding1 or a throw-off switch1 to be provided to intercept runaway vehicles at a distance outside the home-signal for the ascending line1 greater than the length of the longest train running upon the line4 ,under similar circumstances1 when the line is single1 provision for averting danger from runaway vehicles to be made-- 7#a7 ,at a station in one of the following manners3-- 7a7 ,a second line to be laid down1 a second platform to be constructed1 and a catch-siding or throw-off switch to be provided on the ascending line inside the loop-points4 7b7 ,a loop-line to be constructed lower down the incline than the station platform with a similarly placed catch-siding or throw-off switch4 7#b7 ,at a siding-junction in one of the following manners1 except where #bg it is possible to work the traffic with the engine at the lower end of a goods or mineral train1 in which case an undertaking 7see ,no4 #ce7 to do so1 given by the company1 will be accepted as sufficient3-- 7a7 ,a similar loop to be constructed as in the case of a station4 7b7 ,means to be provided for placing the whole train on sidings clear of the main line before any shunting operations are commenced4 #ag4 ,engine-turntables of sufficient diameter to enable the longest engines and tenders in use on the line to be turned without being uncoupled to be erected at terminal stations and at junctions and other places at which the engines require to be turned1 except in cases of short lines not exceeding #ae miles in length1 where the stations are not at a greater distance than #c miles apart1 and the railway company gives an undertaking 7see ,no4 #ce7 to stop all trains at all stations4 ,care to be taken to keep all turntables at safe distances from the adjacent lines of rails1 so that engines1 waggons1 or carriages1 when being turned1 may not foul other lines or endanger the traffic upon them4 #ah4 ,cast-iron must not be used for railway under-bridges1 except in the form of arched-ribbed girders1 where the material is in compression4 ,in a cast-iron arched bridge1 or in the cast-iron girders of an over-bridge1 the breaking weight of the girders not to be less than three times the permanent load due to the weight of the superstructure1 added to six times the greatest moving load that can be brought upon it4 ,in a wrought-iron or steel bridge1 the greatest load which can be brought upon it1 added to the weight of the superstructure1 not to produce a greater strain per square inch on any part of the material than five tons where wrought-iron is used1 or six tons and a half where steel is used4 ,the engineer responsible for any steel structure to forward to the ,board of ,trade a certificate to the effect that the steel employed is either cast-steel1 or steel made by some process of fusion1 subsequently rolled or hammered1 and of a quality possessing considerable toughness and ductility1 together with a statement of all the tests to which it has been subjected4 #ai4 ,in cases where bridges or viaducts are constructed wholly or #bh partially of timber1 a sufficient factor of safety1 depending on the nature and quality of the timber1 to be provided for4 ,n4,b4--,the heaviest engines1 boiler trucks1 or travelling cranes in use on railways afford a measure of the greatest moving loads to which a bridge can be subjected4 ,the above rules apply equally to the main transverse girders and rail-bearers4 #bj4 ,it is desirable that viaducts should1 as far as possible1 be wholly constructed of brick or stone1 and in such cases they must have parapet walls on each side1 not under #d feet #f inches in height above the rail level1 and not less than #ah inches thick4 ,where it is not practicable to construct the viaducts of brick or stone1 and iron or steel girders are made use of1 it is considered best that in important viaducts the permanent way should be laid between the main girders4 ,in all cases substantial parapets1 with a height of not less than #d feet #f inches above rail-level must be provided by an addition to the girders1 unless the girders themselves are sufficiently high4 ,on important viaducts where the superstructure is of iron1 steel1 or timber1 substantial outside wheel-guards to be fixed above the level of1 and as close to the outer rails as possible1 but not so as to be liable to be struck by any part of an engine or train running on the rails4 ,in the construction of the abutments or piers which support the girders of high bridges and viaducts1 cast-iron columns of small size must not be used4 ,in all large structures a wind-pressure of #ef lbs4 per square foot to be assumed for the purpose of calculation1 which will be based on the rules laid down in the report1 dated #cjth ,may1 #ahha1 of the committee appointed by the ,board of ,trade to consider the question of wind-pressure on railway structures4 #ba4 ,the upper surfaces of the wooden platforms of bridges and viaducts to be protected from fire4 #bb4 ,all castings for use in railway structures to be1 where practicable1 cast in a similar position to that which they are intended to occupy when fixed4 #bc4 ,the joints of rails to be secured by means of fish-plates1 or by some other equally secure fastening4 ,on main lines1 and lines where heavy traffic may be worked at high speed1 the chairs not to weigh less than #dj lbs42 but on branch lines1 or lines on which the traffic #bi is light1 chairs weighing not less than #cj lbs4 may be used4 #bd4 ,when chairs are used to support the rails they must be secured to the sleepers1 at least partially1 by iron spikes or bolts4 ,with flat-bottomed rails1 when there are no chairs1 or with bridge rails1 the fastenings at the joints1 and at some intermediate places1 to consist of fang or other through-bolts2 and such rails1 on curves with radii of #ae chains or less1 to be tied to gauge by iron or steel ties at suitable intervals4 #be4 ,in any curve where the radius is #aj chains or less1 a check-rail to be provided4 #bf4 ,diamond-crossings1 as a rule1 not to be flatter than #a in #h4 #bg4 ,no standing work 7other than a passenger platform7 to be nearer to the side of the widest carriage in use on the line than #b feet #d inches1 at any point between the level of #b feet #f inches above the rails1 and the level of the upper parts of the highest carriage doors4 ,this applies to all arches1 abutments1 piers1 supports1 girders1 tunnels1 bridges1 roofs1 walls1 posts1 tanks1 signals1 fences1 and other works1 and to all projections at the side of a railway constructed to any gauge4 #bh4 ,the intervals between adjacent lines of rails1 where there are two lines only1 or between lines of rails and sidings1 not to be less than #f feet4 ,where additional running lines of rails are alongside the main lines1 an interval of not less than #i feet #f inches to be provided1 if possible1 between such additional lines and the main lines4 #bi4 ,at all level crossings of public roads1 the gates to be so constructed that they may be closed either across the railway1 or across the road at each side of the crossing1 and a lodge1 or1 in the case of a station1 a gatekeeper's box1 to be provided1 unless the gates are worked from a signal cabin4 ,the gates must not be capable of being opened at the same time for the road and the railway1 and must be so hung as not to admit of being opened outwards towards the road4 ,stops to be provided to keep the gates in position across the road or railway4 ,wooden gates are considered preferable to iron gates1 and single gates on each side to double gates4 ,red discs1 or targets1 must be fixed on the gates1 with lamps for night use1 and semaphore signals in one or both directions interlocked with the gates1 may be required4 ,at all level crossings of public roads or footpaths1 a footbridge or a subway may be required4 ,at occupation and field crossings1 the gates must be kept hung so as #cj to open outwards from the line4 #cj4 ,sidings connected with the main lines near a public road level crossing to be so placed that shunting may be carried on with as little interference as possible with the level crossing2 and1 as a rule1 the points of the sidings to be not less than #ajj yards from the crossing4 #ca4 ,at public road level crossings in or near populous places1 the lower portions of the gates to be either close barred1 or covered with wire netting4 #cb4 ,mile posts1 half-mile1 and quarter-mile posts1 and gradient-boards to be provided along the line4 #cc4 ,tunnels and long viaducts to be in all cases constructed with refuges for the safety of platelayers4 ,on under-bridges without parapets1 handrails to be provided4 ,viaducts of steel1 iron1 or timber to be provided with manholes or other facilities for inspection4 #cd4 ,continuous brakes 7in accordance with the ,regulation of ,railways ,act of #ahhi71 complying with the following requirements1 to be provided on all trains carrying passengers1 viz4-- 7#a7 ,the brake must be instantaneous in action1 and capable of being applied by the engine-driver and guards4 7#b7 ,the brake must be self-applying in the event of any failure in the continuity of its action4 7#c7 ,the brake must be capable of being applied to every vehicle of the train1 whether carrying passengers or not4 7#d7 ,the brake must be in regular use in daily working4 7#e7 ,the materials of the brake must be of a durable character1 and easily maintained and kept in order4 #ce4 ,any undertaking furnished by a railway company to be under the seal1 and signed by the chairman and secretary of the company4 ,recommendations as to the ,working of ,railways4--#a4 ,there should be a brake vehicle1 with a guard in it1 at or near the tail of every passenger train2 this vehicle should be provided with a raised roof and extended sides1 glazed to the front and back1 and it should be the duty of the guard to keep a constant look-out from it along his train4 #b4 ,all passenger carriages should be provided with continuous footboards1 extending the whole length of each carriage and as far as #ca the outer ends of the buffer castings4 ,as passenger carriages pass from one company's line to another's1 it is essential for the public safety that1 although the widths of the carriages on the different lines may differ from each other1 the widths across the carriages from the outside of the continuous footboard on one side1 to the outside of the continuous footboard on the opposite side1 should be identical for the carriages of all railway companies1 so that the lines of rails may be laid at the proper distance from the edges of the passenger platforms4 #c4 ,there should be efficient means of communication between the guard1 or guards1 of every passenger train and the engine-driver1 and between the passengers and the servants of the company in charge of the train4 #d4 ,the tyres of all wheels should be so secured as to prevent them from flying open when they are fractured4 #e4 ,the engines employed with passenger trains should be of a steady description1 with not less than six wheels1 with the centre of gravity in front of the driving-wheels1 and with the motions balanced4 ,they should1 as a rule1 be run chimney in front4 #f4 ,records should be carefully kept of the work performed by the wearing parts of the rolling stock1 to afford practical information in regard to them1 and to prevent them from being retained in use longer than is desirable4 #g4 ,in addition to the block-telegraph instruments1 it is desirable that there should be speaking-instruments1 or telephones1 for communication between signalmen1 and books for recording the running of the trains4 #h4 ,when drovers or other persons are permitted to travel with goods or cattle trains1 suitable vehicles should be provided for their accommodation4 #i4 ,it is considered that1 in fixed signals1 the front lights should show-- ,green1 for all right2 ,red1 for danger2 and that back lights1 visible only when the signals are at danger1 should show white4 #aj4 ,refuge sidings should be provided at all main-line stations where slow trains are liable to be shunted for fast trains to pass them4 ,if at such stations it is impossible to provide refuge sidings1 and slow #cb trains have to be shunted from one main line to the other to allow of fast trains passing them1 some simple arrangements should be supplied in the signal cabins to help to remind the signalman of the shunted train4 #aa4 ,efficient means should be adopted to prevent the accidental opening of the doors of passenger trains4 99 99 99 99 99 ,to carry out the undertaking1 the engineer has to prepare working plans and sections to a somewhat larger scale than that adopted for the ,government or ,parliamentary plans1 and on which must be marked the exact positions of the commencement of the curves1 straight lines1 and gradients4 ,the sites of all the over and under bridges must be shown1 and their angles of crossing noted4 ,all road1 river1 or stream diversions must be indicated1 so that the work in connection with them may be laid out on the ground4 ,all culverts and drains must be marked1 and their size1 depth1 and direction described4 ,public road level-crossings1 and farm or occupation-road crossings1 must be shown in their proper positions4 ,the face-lines of the ends of all tunnels should be marked on the working plan and section1 and the position of any shafts1 which may be intended either for use in carrying on the work or for future ventilation4 ,a considerable amount of investigation and negotiation will have to be entered into before the locating of the above works can be finally decided4 ,the desire to meet the wishes and convenience of all parties interested must of necessity be controlled by the physical circumstances of each case2 very little alteration can be made in the level of the rails1 although some variation may be made in their position4 ,when fixing the depths of culverts and drains1 attention must be paid to any probable improvement in the drainage of the district1 which might at some future time necessitate the deepening of such of the main culverts where the inverts had been laid too high4 ,unless all these details are determined1 and shown on the working-plans before the works are commenced1 there is the risk that embankments may have to be opened out to admit of bridges and culverts1 and cuttings changed to permit of road diversions4 ,the entire centre-line of railway must be carefully staked out by #cc driving strong wooden pegs into the ground at the end of every chain length1 and along the course of these pegs the longitudinal section must be taken4 ,three pegs1 one on each side of the centre peg1 are generally placed at the commencement and termination of the curves4 ,when the longitudinal section has been plotted to scale1 and the course of the gradients and level portions worked out and drawn on1 then the heights of the ground level and formation level can be marked at each chain1 and from them the depths of the cutting and the heights of the embankments can be ascertained and marked at each chain4 ,in addition to the longitudinal section1 it will be necessary to take a large number of transverse or cross sections at those pegs1 or intermediate points1 where the ground is at all side-lying or irregular4 ,these cross-sections are necessary to determine the side-widths1 or distances to outer edge of slopes in cuttings or embankments1 and also to calculate the actual quantity of earthwork to be executed4 ,for convenience in taking out the quantities1 these cross-sections are generally plotted to a natural scale1 that is to say1 to the same scale horizontal as vertical1 as shown in the example of cross-sections1 ,figs4 #ae to #bd4 ,it is also necessary to obtain information1 by boring or otherwise1 as to the material of which the cuttings are composed1 whether clay1 gravel1 or rock4 ,in laying out lines through fairly level plains and populous districts1 the absence of great natural obstacles will allow the engineer to carefully consider how far it may be prudent to diverge to the right or to the left1 to accommodate towns and places which would be excluded by a more direct through route4 ,there will be ample range for selection1 and it will be rather the question of policy than compulsion which will guide him in the route to be taken4 ,illustration3 ,fig4 #ab1 #ac1 #ad1 #ae1 #af1 #ag1 #ah1 #ai1 #bj1 #ba1 #bb1 #bc1 #bd ,when1 however1 the locating passes from the lower ground1 away up amongst the hills and mountain ranges1 it becomes an intricate study whether it will be possible to lay out any line at all which may possess gradients and curves practicable for railway working4 ,the question of property1 population1 or convenience of access1 is here no longer the controlling influence1 but in its stead there are the far more formidable natural difficulties to be overcome in working out a trackway to the inevitable summit level4 ,the chief endeavour will be to gain length1 and so reduce as much as possible the steepness of the gradients which at the best must necessarily be severe4 ,in some of the #ce earlier mountain lines constructed abroad the system of zigzags was introduced1 as shown in ,fig4 #be4 ,these zigzags were laid out on ruling gradients1 one above the other1 on the sides of the mountain slopes with pieces of level at the apices1 ,a1 ,b1 and ,c1 on which the engine could be changed from one end of the train to the other4 ,although feasible in principle1 the system entailed considerable loss of time in train-working1 and was not unattended with risk4 ,the more modern and simple method of working out the same idea is to connect the main zigzag lines by curves or spirals1 thus rendering the route continuous and unbroken4 ,by this arrangement the heavy work and delay in starting or stopping the train at the apices1 ,a1 ,b1 and ,c1 as shown on ,fig4 #be1 is avoided1 and the train can proceed continuously on its circuitous journey4 ,fig4 #bf shows an instance of the zigzags and spirals1 as carried out on an important railway abroad4 ,to have made a direct line from ,d to ,e1 the most difficult part of the route1 would have involved a gradient of #a in #aa2 but by constructing the spiral course1 as shown1 the length was more than trebled1 and the gradient reduced to #a in #ce4 ,fig4 #bg is another example of spiral zigzags in which advantage was taken to cut a short tunnel through a high narrow neck of rock at ,g1 and then by skirting round the hill the line was taken over the top of the tunnel and along the side of the mountain to the summit tunnel at ,h4 ,by this means the line from ,f to ,h was laid out to an average gradient of #a in #db4 ,fig4 #bh shows the ,cumbres inclines on the ,mexican ,railway4 ,the route had to be located through one of the rugged passes of the great ,chain of the ,andes1 whose mountain-sides rise most abruptly from the lower plains1 to the great upper-land plateau1 some eight thousand feet above sea-level4 ,the ground to be traversed was so steep and difficult that1 even with the best available detours and greatest length that could be obtained1 the result was an average continuous gradient of #a in #be for #ab miles4 ,illustration3 ,fig4 #be1 #bf1 #bg1 #bh1 #bi ,fig4 #bi is a plan of part of the ,st4 ,gothard ,railway1 showing the principal tunnel #i miles long1 and some of the adjoining spiral tunnels4 ,the long tunnel through the great ,alpine barrier was the only means of forming a railway connection between the two points at ,airolo and ,goeschenen4 ,constructed in a straight line1 with easy gradients1 #cg falling towards the entrances1 efficiency of drainage has been secured1 and excessive strain on motive-power avoided4 ,the approaching valleys on each side were in some places too irregular and broken to admit of zigzag loops1 and the spiral tunnels were adopted instead4 ,the enlarged plan of two of the spiral tunnels will explain the method of working4 ,an ascending train enters the first tunnel at ,a1 and after passing round almost an entire circle1 on a rising gradient1 emerges at a much higher level at the point ,b4 ,proceeding onward1 the train enters the second tunnel at ,c1 and after passing round a similar circle1 on a rising gradient1 comes out at a still higher point1 ,d1 and continues its course up the valley4 ,the last five sketches illustrate some of the methods which have been adopted when constructing railways through some of the most difficult mountain ranges4 ,they show what has been done1 and may serve as guides in working out the location of a line in some hitherto unexplored region4 ,gauge4--,the gauge of a railway1 or its width from inside to inside of rails1 affects both its cost and efficiency4 ,if the gauge be exceptionally wide1 then the expenditure on works and rolling-stock will be proportionately heavy2 and although theoretically the extra wide gauge may possess greater capabilities for accommodation and high-speed travelling1 we may find in practice that the necessary requirements may be provided on a much more moderate gauge4 ,on the other hand1 if the gauge be exceptionally narrow1 there will be diminished convenience both for passengers and merchandise1 and a corresponding limit to the speed in transit4 ,in isolated districts1 where passenger traffic is of secondary importance1 and where the principal merchandise will be heavy without being bulky1 such as mineral ores1 slates1 etc41 a comparative narrow gauge may possibly suit the purpose4 ,for main trunk lines1 however1 where a large1 heavy1 and fast passenger traffic will have to be worked1 and where goods of all kinds1 many of them bulky without being heavy1 will have to be carried1 an ample gauge must be selected to ensure convenience and safety4 ,a liberal gauge permits the use of commodious rolling-stock without any great amount of lateral overhanging weight outside the wheels2 whereas with a narrow gauge there is the tendency--if not the necessity--to use vehicles which have too great a lateral overhang for proper stability1 except at very #ch moderate speeds4 ,the following list shows the gauges adopted in various countries3-- ft4 ins4 ,england1 ,scotland1 and ,wales #d #h ,ireland #e #c ,united ,states #d #h1 with some lines #e ft41 #e ft4 #f ins41 and #f ft4 ,canada #d #h and #e ft4 #f ins4 ,france #d #h ,belgium #d #h ,holland #d #h ,germany #d #h ,austria #d #h ,switzerland #d #h ,italy #d #h ,turkey #d #h ,hungary #d #h ,denmark #d #h ,norway #d #h and #c ft4 #f ins4 ,sweden #d #h ,mexico #d #h and #c ft4 ,egypt #d #h and #c ft4 #f ins4 ,peru #d #h ,nova ,scotia #d #h and #e ft4 #f ins4 ,new ,south ,wales #d #h ,brazil #d #h1 #e ft4 #c ins41 and #e ft4 #f ins4 ,uruguay ,republic #d #h ,russia #e #j ,south ,australia #e #c ,new ,zealand #c #f ,british ,india #e #f and #a metre4 ,ceylon #e #f ,spain #e #f ,portugal #e #f ,chili #e #f ,argentine ,republic #e #f ,cape ,colonies #c #f ,japan #c #f ,after many years' experience of actual working1 the broad1 #g feet1 gauge of the ,great ,western ,railway has been abandoned for the #d feet #h inch gauge4 ,doubtless this decision was the result of most careful deliberation1 and was made upon convincing proof that the #d feet #h inch gauge could fulfil all the advantages claimed for the wider gauge1 whilst at the same time it possessed the merit of less cost of construction and working1 and greater facilities for the exchange of traffic with other lines having the standard gauge4 ,the facility of exchange1 or through working of rolling-stock1 is a leading element of successful railway working1 and it is difficult to estimate what would be the amount of loss and delay if we had any great extent of break of gauge on the main trunk lines of our own country4 ,although some countries have selected gauges of #e feet and #e feet #ci #f inches1 it is interesting to note that the largest number have adopted the ,english standard gauge of #d feet #h inches1 and that the miles of line laid to this gauge far outnumber all the others4 ,the fact that our own home lines1 the principal ,continental lines1 and nearly all that vast network of railways in the ,united ,states of ,america1 have been laid to the #d feet #h inch gauge1 testifies to the general opinion of its utility and efficiency2 and we know that included in that list are the railways which carry the largest1 heaviest1 and fastest train service in the world4 ,it would be interesting to trace back1 and1 if possible1 ascertain from whence the exact gauge of #d feet #h inches was derived4 ,no doubt1 in the early days of the pioneer iron highways in ,england1 the railways were made the same gauge as the tramroads which they superseded4 ,but why was #d feet #h inches the gauge of the tramroads8 ,we may reasonably infer that the first four-wheeled waggons used on the early tramroads were in reality the same waggons which had been previously used on the common roads for the conveyance of coal and minerals to the ports for shipment1 and that the waggons were merely transferred from the roughly paved or macadamised roads to the tramroads4 ,flanged wheels were then unknown1 and the introduction of the tram-plates was at first simply designed to lessen the resistance to haulage4 ,the gauge1 or width between the wheels1 of these waggons may have been the outcome of long experience as to the most suitable width for convenience of load1 stability during transit1 or for space occupied on the highway4 ,the width may have been handed down from generation to generation1 going back to the time when wheeled vehicles were first built in the country4 ,perhaps in the beginning the first vehicles may have been imported from ,italy1 or ,greece--countries which in the earlier ages were the most advanced in matters of luxury and convenience4 ,when in ,pompeii1 a few years ago1 the writer measured the spaces between a large number of the wheel-ruts which are worn deep into the paving-stones in many of the principal streets of that wonderful unearthed city4 ,these paving-stones1 very irregular in shape1 and many of them #b feet #f inches long by #a foot #f inches wide1 are carefully fitted together1 and form a compact massive pavement from curbstone to curbstone4 ,the wheel-tracks1 which are in many places worn into the stones to the depth of an inch or an inch and a #dj half1 are always distinct1 and there is no difficulty in defining the corresponding track4 ,the result of a large number of measurements gave an average width of about #d feet #aa inches from centre to centre of the wheel-tracks1 a curious coincidence with the gauge of our own road vehicles at the beginning of the railway era4 ,whether our selection of the railway gauge of #d feet #h inches has been the result of study1 imitation1 or caprice1 we certainly have the silent testimony of these old deep-worn stones to prove that two thousand years ago the chariots of ,pompeii were of very similar gauge to our own of modern times4 ,narrow-gauge railways1 of gauges varying from #a foot #aj inches on the ,festiniog ,railway1 to #c feet1 #c feet #c inches 7metre71 and #c feet #f inches1 have been made in several places both at home and abroad4 ,generally speaking1 they have been constructed as subsidiary or auxiliary lines in thinly populated districts1 with a view to afford some railway accommodation where it was considered that lines of the standard gauge would not pay4 ,in some instances abroad long lines of narrow gauge--#c feet and #c feet #f inches--have been constructed as main trunk lines in newly opened out districts4 ,some of these have since been altered to a wider gauge as the traffic developed1 and experience proved that the narrow width of the vehicles was unsuitable for quick transit1 or convenience in the accommodation of passengers and goods4 ,the object in making a line to a narrow gauge is doubtless to save cost in the original construction2 but when a scheme for an altered gauge is put forward1 it will be well to consider what amount of advantage or saving would be effected by deviating from the standard gauge4 ,if there be almost a certainty that such proposed line will always remain isolated from all other existing railways of the standard gauge1 then perhaps the selection of gauge may be one of minor importance1 and there remains but the question whether the description of traffic1 and the weights to be carried1 can be worked to any greater advantage1 or more economically1 by deviating from the standard gauge4 ,if1 however1 there be a fair probability that such proposed line may at some future time become part of an already established railway system1 it would appear to be more prudent to make the line to the standard gauge1 and effect economies by introducing steeper gradients1 #da sharper curves1 and lighter permanent way1 and keep down working expenses by using lighter locomotives1 worked at slower speeds4 ,high speeds are not expected on narrow gauge railways1 and no complaints are made about passenger trains whose highest running speed does not exceed #bj miles per hour4 ,by conceding the same indulgence to light railways made to the standard gauge1 great economies might be introduced both in their construction and working4 ,the similarity of gauge would admit the transit of the carriages and waggons of other standard gauge lines1 and so avoid all cost and delay in transshipment4 ,the heavy engines could be kept for the main-line working1 and light engines for slow speeds would serve for the light standard-gauge lines4 ,as traffic developed1 and the train service required heavier and faster trains1 the light rails could be removed1 and replaced by those of heavier section to correspond to the main line4 ,the similarity of gauge would permit uninterrupted transit of all vehicles to a common centre for repairs1 whereas the narrow gauge carriages and waggons1 being limited to running only on their own district1 must have separate workshops for their repair4 ,when considering the cost of construction and working of a narrow-gauge railway as compared with one of the standard gauge1 there are certain items which are common to both1 and in which the narrow gauge could not be expected to obtain any advantage over the standard gauge4 ,there would not be any saving in getting up the scheme in the first instance2 ,nor in the ,parliamentary expenses2 ,nor in the engineering or carrying out of the works2 ,nor in the station accommodation1 waiting-rooms1 and offices2 ,nor in the signals and interlocking arrangements2 ,nor in the telegraph2 ,nor in the working staff and train men2 ,nor in the maintenance of the permanent way1 as the same number of men would be required for the inspection and packing of the road1 perhaps more4 ,little or no saving could be expected in the bridges under the railway1 as these must be made to the prescribed widths and heights1 irrespective of the gauge of the railways4 ,little1 if any1 saving could be made in river or stream bridges1 as the #db same amount of waterway would have to be provided in each case4 ,the same remark applies to culverts and drains4 ,there would1 on the other hand1 be a small saving in the quantity of land to be acquired to the extent of a narrow strip or zone1 represented by the difference in width between the narrow and standard gauges4 ,there would also be the same small proportionate saving in the embankments and cuttings to the extent of the difference in gauge4 ,also a saving in the overline bridges and road approaches in consequence of less width and height of the opening through those bridges4 ,and a saving in the rails1 sleepers1 and ballast of the permanent way1 to the extent consistent with efficiency4 ,that some saving may be effected in these is undoubted1 but it is necessary to exercise caution1 and not rush to the opposite extreme by making the parts too light4 ,a rail should be made not only strong enough to carry well the engines that have to pass over it1 but it should also be heavy enough to stand the wear of several years4 ,narrow-gauge engines must be heavy in conformity with the loads they have to haul4 ,the same amount of power must be exerted to haul a hundred tons on a given gradient1 whether the gauge be narrow or broad4 ,in some cases of narrow-gauge railways the original rails1 which weighed only #de lbs4 per yard1 have since been replaced with others weighing #fj and #fe lbs4 per yard4 ,the light #de lb4 rails were evidently not found to be sufficiently heavy to keep the road to proper line and level4 ,the result of our everyday practice seems to prove that there is not only an advantage1 but an economy1 in adopting rails of a heavy section1 and experience would therefore indicate that even for a narrow-gauge railway it may not be expedient to adopt rails weighing less than #fe lbs4 per yard4 ,gradients4--,there are very few localities where the rails on any line of railway can be laid perfectly level or horizontal for more than comparatively short distances4 ,by far the greater portion have to be laid on inclined planes of varying rates of inclination to suit the general formation of the district traversed1 and the circumstances of the line to be constructed4 ,the degree1 or rate of inclination1 of these inclined planes1 or gradients1 may be expressed in various ways4 ,a very general method is #dc to state the number of feet1 metres1 etc41 which can be measured along the gradient before an increased rise or fall of one foot or metre1 etc41 is obtained4 ,thus a gradient of #a in #bjj signifies a rise or fall of #a foot in #bjj feet1 or #a metre in #bjj metres4 ,sometimes the rate of inclination is expressed by stating the number of feet of rise or fall in a mile4 ,in this way a gradient would be described as falling at the rate of #cj feet in a mile1 rising at the rate of #bj feet in a mile1 etc4 ,twenty feet to a mile is equal to #a in #bfd4 ,another method is to give the percentage of rise or fall4 ,in this way the inclination would be expressed as a #a per cent4 gradient1 #b per cent4 gradient1 per cent4 gradient1 etc41 which for comparison would signify #a in #ajj1 #a in #ej1 and #a in #bjj respectively4 ,the gradients of a railway most materially influence its facility and cost of working1 and every effort should be used to make them as easy as possible consistent with the prospect of the line4 ,steep gradients signify heavy locomotives1 increased cost of motive-power1 reduced speed1 and light loads4 ,the following tabulated memoranda show the approximate loads1 exclusive of engine and tender1 which can be hauled on the level and on certain inclines at various speeds by engines of the quoted capacities and steam admissions4 ,a medium-sized1 ordinary type of passenger and goods engine has been selected for each of the examples4 ,the working of the passenger engine and train is assumed to be under favourable circumstances1 with fine weather1 fairly straight line1 first-class permanent way1 modern rolling-stock with oil axle-boxes and perfect lubrication1 and all the conditions most suitable to ensure the least resistance to the moving load4 ,for the goods engine and train a greater resistance per ton of load is assumed1 as the goods trucks are never so perfect or easy in the running as the passenger carriages4 ,a certain amount of side wind is taken into consideration1 and also an allowance for moderately sharp curves1 the object being to indicate what may be looked upon as fair1 average1 workable loads4 ,the loads for engines of larger or smaller dimensions1 or higher or lower pressures1 may be obtained by working out the proportion between #dd the tractive force put down in any of the columns of the tabulated memoranda and the ascertained tractive force of any other engine under the same conditions of cut-off and speed4 ---------------------------------------- --------------------------------- ,,passenger ,,engine4 ,,goods ,,engine4 ,six wheels1 driving ,six wheels1 all coupled1 and trailing wheels #d ft4 #f ins4 diameter4 coupled1 #f ft4 #f ins4 ,cylinders1 diameter4 ,cylinders1 #ag ft4 #bd ft4 #ag ft4 #bd ft4 ,locked-down pressure on ,locked-down pressure on safety-valves1 #adj lbs4 safety-valves1 #adj lbs4 per square inch4 ,assumed per square inch4 ,assumed pressure at cylinders1 pressure at cylinders1 #abj lbs4 per square inch4 #abj lbs4 per square inch4 ,weight of engine #ci tons4,weight of engine #cd tons4 0 tender #bd 0 0 tender #bd 0 -- -- #fc 0 #eh 0 ---------------------------------------- --------------------------- ,assumed cut-off 0 mean effective pressure1 lbs4 #de #ef #gf #ajj #de #ef #gf #ajj 0 tractive force1 lbs4 #djjj #digi #fgeh #hhib #eghj #gaib #igfj #abhdd ,speed in miles per hour #fj #dj #cj #ae #dj #cj #bj #ae ,tons4,tons4,tons4 ,tons4 ,tons4,tons4,tons4 ,tons4 ,level #ig #bcj #ddg #hib #bac #ceh #fbc #ijg #a in #ajjj #hd #aif #cgc #gjg #ahg #caj #ecb #gfh 0 #hjj #ha #ahh #ceh #fga #aha #bii #eab #gci 0 #fjj #gf #agg #cce #fah #agb #bhe #dhb #fie 0 #djj #fh #aeg #bif #ecc #aeg #beg #dcb #fba 0 #cjj #fj #ada #bfc #dfg #adc #bcc #cij #efj 0 #bej #ee #abi #bda #dbd #acc #baf #cfa #eai 0 #bjj #dg #aad #bac #cgb #abj #aie #cbd #dfg 0 #aej #cg #ic #agg #cjd #aja #afe #bgf #cig 0 #ajj #ba #fc #abf #bag #gd #abc #bjh #cjb 0 #ij -- #ef #aad #aig -- #aac #aia #bgi 0 #hj -- #dh #aja #age -- #aja #agb #bec 0 #ge -- #dc #id #afd -- #ie #afc #bdj 0 #gj -- #ci #hf #aeb -- #hh #aec #bbf 0 #fj -- #bh #gj #abh -- #gd #aca #aif 0 #ej -- -- #ec #aja -- -- #ajg #afc 0 #dj -- -- -- #gc -- -- -- #abg 0 #be -- -- -- #bg -- -- -- #fg ---------------------------------------- --------------------------- ,,note4--,the column loads in tons are exclusive of the weight of engine and tender4 ,from the above memoranda it will be seen how greatly the gradients #de affect the loads4 ,for an important main trunk line1 with a heavy and frequent train-service of passengers and goods1 the introduction of steep gradients would not only reduce the speed of the train-working1 but would probably involve the necessity of assistant engines over those parts of the line2 and it may be prudent1 where possible1 to incur heavier earthworks1 or considerable detours1 or tunnels1 to obtain more favourable gradients4 ,for such a line the additional cost1 and the extra distance caused by a detour of a mile or more1 will be of far less importance than the interruption in the train service arising from a serious reduction in speed or taking on assistant engines4 ,on many railways abroad there are very interesting examples of long detours of several miles1 carefully studied out to obtain greater length and easier gradients1 resulting in the construction of lines over which the traffic can be worked without necessitating auxiliary engine-power4 ,on the other hand1 there are situations where steep gradients cannot be avoided1 where certain altitudes must be reached1 and where there is no alternative but to face the inevitable4 ,on secondary lines1 and short branch lines1 where the traffic is not expected to be heavy1 and where speed is not so important1 it may be policy to economize outlay and introduce steeper gradients than on the main line4 ,half a mile of a rather steep gradient is not felt so much when it is situate midway between two stations1 because the attained speed of the train assists the engine over the short distance to the summit2 but when it occurs as a rising gradient out of a station1 it forms a great check to the working1 particularly in bad or wet weather1 when there is the risk of the engine slipping1 and the entire train sliding back into the station4 ,long steep gradients not only necessitate increased motive-power for the ascending trains1 but also require increased brake-power1 and precautionary measures for the descending trains4 ,where passenger trains are fitted with continuous brakes1 the risk of losing control is minimized2 but with goods trains composed of waggons1 having only the ordinary independent side-lever brake1 it will be found absolutely necessary in many cases to have additional heavy brake-vans for descending the inclines1 and these special vans1 unfortunately1 will form so much extra non-paying weight to be hauled up on the ascending trains4 ,of course1 it is quite possible--and1 indeed1 in many places #df it is customary--to pin down some of the side-lever brakes before commencing the descent1 but once pinned down the brakes cannot be eased or taken off until the entire train is brought to a stand4 ,every goods waggon should be fitted with a brake1 and it would be of immense value if that brake could in all cases be applied and controlled when the train is in motion4 ,the ,american type of long goods waggon1 with a four-wheel bogie-truck at each end1 is fitted with a brake very similar to those adopted on the ordinary horse tram-cars4 ,on the top of the waggon a horizontal iron hand-wheel1 about #ah inches in diameter1 is fixed on to a strong vertical iron rod1 which works in brackets1 and extends down below the underside of waggon framing4 ,one end of a short length of chain is secured to the foot of the vertical rod1 and the other end is connected by light iron rods to the series of levers which pull on the brake-blocks4 ,by rotating the horizontal hand-wheel the chain is coiled round the lower end of the vertical rod1 the brake-levers are pulled over1 and brake-pressure applied to the wheels of the waggon4 ,the brakesman is supplied with a convenient seat and footboard1 and on the floor-level of the latter there is a pawl and ratchet attached to the vertical rod1 which permits the brakes to be applied to the extent required4 ,the pawl retains the brakes in position until the brakesman with his foot pushes the pawl out of the notch of the rachet and releases the brake gearing1 which is at once pulled off quite clear by strong bow-strings attached to the framework of the bogies4 ,this type of hand-brake is1 perhaps1 the simplest that can be made4 ,the brakesman has merely to put it on1 the pawl and ratchet keep it on1 and the bow springs take it off when no longer required4 ,each one of these long1 loaded goods waggons becomes a very serviceable brake-van1 and for ascending and descending steep inclines all that is necessary is to take on a few additional brakesmen to manage the brakes of as many suitable waggons4 ,these incline brakesmen1 after going down1 can return to the summit by the next ascending train1 their small weight being a mere nothing as compared with that of special or extra brake-vans4 ,on some ,european lines it is the custom to sprag some of the goods waggon wheels when going down exceptionally steep inclines1 as well as #dg applying the brakes on the ordinary and extra brake-vans4 ,the sprag is a piece of wood1 circular in section1 about #b feet #f inches long1 and #e to #f inches thick in the middle1 tapering off to about #b inches thick at the ends4 ,when the waggon-wheel is just beginning to move1 the sprag is inserted between the spokes1 and being caught against the waggon framework1 the wheel is held fast1 and being unable to revolve1 remains fixed1 and acts like a skid upon the rails4 ,the skidding of the wheels upon the rails wears flat places on the wheel tyres1 and it is needless to mention that the practice is only resorted to in very extreme cases4 ,although a very primitive means for checking the speed of a descending train1 or for maintaining vehicles stationary on an incline1 there have been many instances where lives have been saved and accidents prevented by the prompt use of a few sprags4 ,solid or close wheels cannot be spragged1 only wheels which have spokes or openings1 and for this reason alone it would be very desirable that in every passenger and goods train there should be some spoke or open wheels which could be spragged as a last resource1 in the event of a sudden emergency of brakes failing or train becoming divided on an incline4 ,on ascending gradients there is always the risk of a coupling breaking1 and the train becoming divided4 ,if the detached portion left behind be provided with ample brake-power1 hand-brakes1 or otherwise1 no harm may take place beyond a little delay2 but if the brake-power be insufficient or defective1 and if all the wheels are solid wheels incapable of admitting a few timely sprags1 then the vehicles cannot be held1 but must slide back1 and running unchecked would soon attain such a velocity as would cause them either to leave the rails or dash into another train standing at the last station4 ,many lamentable accidents have taken place arising from portions of trains breaking away and running back1 and the sad experience of those casualties should call forth every effort to avert a recurrence in the future4 ,it may not always be possible to detect a hidden flaw in a coupling1 or a defect in the brake-gearing until the actual failure occurs2 but it is quite possible to guard against disastrous results from such failure1 by providing means to hold the vehicles1 and prevent them sliding back4 ,for some years the writer had the entire charge of an important railway abroad on which the gradients were very exceptional1 and where #dh it was absolutely necessary that he should organize the most complete precautions to prevent the possibility of trains1 or portions of trains1 running back down inclines4 ,starting from sea-level1 the line1 which was laid to the #d feet #h inch gauge1 rose to a summit of over #hjjj feet1 and on the mountain division there were many long gradients of #a in #dj1 #a in #cc1 and in one place a continuous gradient of #a in #be for #ab miles4 ,the specially powerful engines reserved for these heavy inclines were each supplied with an ordinary hand-brake1 a steam-brake1 and a ,westinghouse continuous brake4 ,the passenger carriages1 which were of considerable length1 and carried on a four-wheeled bogie-truck at each end1 were all fitted up with the ,westinghouse brake1 and in addition each carriage had its own hand-wheel brake with the pawl and ratchet gearing4 ,all the goods waggons1 which were of the ,american type1 were fitted with hand-wheel brakes similar to those on the carriages4 ,special gangs of trained brakesmen took charge of the trains on these inclines1 a brakesman to every carriage or waggon1 and were always in readiness in case of the breakage of a coupling1 or the failure in the ,westinghouse brake or brakes on engine4 ,the immunity from accidents justified the combined precautions adopted1 and proved the possibility of working such severe gradients with perfect safety4 ,the long-continued application of the brakes on heavy inclines naturally leads to the question as to the description of wheel to be adopted for the work4 ,not only are the wheels subjected to very severe torsional strains1 but the temperature at the circumference is raised very high in consequence of the friction4 ,perhaps1 theoretically1 the safest wheel would be one made out of a solid piece of metal1 similar to the chilled cast-iron wheels of the ,united ,states1 or the steel disc wheels used on some lines in ,europe1 in either of which holes can be left for sprags4 ,wheels of this description can withstand very heavy wear and tear1 they are not affected by increased temperature1 and they certainly have the minimum of parts to work loose4 ,of the built-up wheels1 the strong forged-iron-spoke wheel with steel tyres shows excellent results1 and always gives due warning of loosening by indications at the tyre rivets4 ,the suddenness with which the solid wooden centre wheels sometimes break up and fall to pieces does not commend them for a service where there must be a long-sustained application of the brakes4 ,the increased temperature which expands the #di tyre1 contracts the wood1 and must loosen and weaken the entire wheel4 ,on all steep gradients the road-bed should be of the most substantial character1 and the permanent way of a strong description1 and maintained in perfect order1 as the engines for working the traffic must necessarily be of a heavy type4 ,the rails will be severely tested by the pounding and slipping of the engines on the ascending journey1 and by the action of the brakes on the descending journey4 ,in the early days of the railway system1 rope-haulage was adopted on some of the main lines for working the trains on steep inclines near the principal terminal stations4 ,a powerful stationary engine1 located at the highest point1 was employed to work an endless rope which passed round large drums at the top and bottom of the incline1 and was supported on sheaves or pulleys fixed between the rails4 ,the connection between the carriages and endless rope was effected by means of a short piece of rope called the messenger1 which was coiled round the main rope in such a manner as to be readily detached when the train reached the summit4 ,there are many persons who will remember the time when the passenger trains were hauled by an endless rope up the #a in #ff incline from ,euston to ,camden ,town1 a distance of about a mile and a half1 and up the #a in #dh incline from ,lime ,street1 ,liverpool1 to ,edge ,hill1 a distance of about a mile and a quarter1 and several others4 ,the rapid strides made in locomotive construction1 and the increased pressure used in the boilers1 enabled much more powerful engines to be built1 until one by one the rope-haulage machinery has disappeared from nearly all the inclines where for years it had been considered indispensable4 ,rope-haulage on inclines is now very rarely met with1 except at collieries and ironworks1 where occasionally the rope may be seen so arranged that the loaded waggons descending pull up the empty waggons on the opposite or parallel line4 ,curves4--,the degree of curvature of a railway curve is generally expressed by giving the radius in feet1 chains1 metres1 or other national standard measure4 ,when laying out a line of railway1 the natural features of the country will necessitate the introduction of curves1 and the question for consideration will be whether they are to be made of small or large radius4 ,in some cases sharp curves are inevitable1 except by incurring #ej enormous works which would not appear to offer any corresponding prospective recompense4 ,in others the curves may be made of easy radius1 at a comparative moderate extra outlay1 if the character of the line and description of traffic to be accommodated will warrant the expenditure4 ,for main through lines1 with heavy1 high-speed traffic1 it is advisable to have the curves of large radius1 so as to avoid the necessity of reducing speed when passing round them4 ,although a high-class fast train may be allowed to run round an #hj chain 7#ebhj feet7 curve at almost unrestricted speed1 safety demands that there should be a reduction of speed on curves of #dj or #cj chains radius1 and a very much greater reduction for curves of #bj chains radius and under4 ,a sharp curve will in some places form a greater check to fast trains than a length of moderately steep gradient on a straight line4 ,in the former the trains running in either direction must slow down for some distance before reaching the curve1 round which they should pass at greatly reduced speed1 and then some distance must be run before they can attain their full speed again4 ,on the other hand1 with a rising gradient1 on a fairly straight line1 the acquired momentum of the train will materially assist in ascending the incline1 and although the speed may be slackened as the train advances1 there may not be any very great diminution in the running before the gradient is passed1 and average level line reached again4 ,a reduced rate of running must be maintained round curves of small radius1 for1 however substantial the works and permanent way1 and however well devised and constructed the rolling-stock1 there is an element of danger ever present when passing round sharp curves at anything more than moderate speed4 ,in the great rush for fast through trains this point is very apt to be overlooked1 and too little time allowed for the running4 ,even with the fastest trains on any line there are some portions of the route which must be traversed with greater caution and less speed than others1 either on account of sharp curves or of gradients2 and if those who are entrusted with the preparations of the time tables do not possess the technical information necessary to deal properly with the question of relative speeds1 there is the strong probability that the programme prepared may be one both difficult and dangerous to fulfil4 ,the spirit of rivalry is a strong incentive to fast running1 but prudence and common sense should indicate that record speeds should only be attempted on #ea the straight or favourable portions of the line4 ,there is1 unfortunately1 the growing tendency to run faster and faster round the curved portion of our lines1 heedless of the close approach to the limit of safety1 and unless this excessive speed be controlled in time1 the result must be disaster on a very large scale4 ,a sharp curve leading into or out of a terminal station or main-line stopping-station does not so much affect the train running as a sharp curve at an intermediate point between stations where the train may be expected to run at its maximum speed4 ,wherever it is possible it is very desirable to avoid sharp curves on inclines1 because there are times when descending trains may acquire a considerable velocity1 and wheels tightly gripped by the brakes have not the same facility for following the curves as when they are running free4 ,in rugged and mountainous districts sharp curves are almost unavoidable1 except by introducing a series of tunnels2 but in these districts both the gradients and curves are alike exceptional1 the speed is necessarily slow1 and special precautions are taken for the ascending and descending trains4 ,illustration3 ,fig4 #cj1 #ca1 #cb1 #cc1 #cd1 #ce1 #cf1 #cg1 #ch ,when setting out reverse curves on a main line a piece of straight line should always be laid in between the termination of the one curve and the beginning of the other1 to allow of a proper adjustment of the rails to suit the super-elevation adopted on each of the adjoining curves4 ,in station yards and sidings this is not so absolutely necessary1 the sorting of the carriages and waggons and the marshalling of the trains being carried on at a low speed1 which does not necessitate any super-elevation of the rails on the curves4 ,the speed of the train regulates the amount of super-elevation to be given on any particular curve1 and to ensure smooth and safe running this amount must be maintained uniform all round the curve4 ,on curves of small radius1 guard1 or check1 rails are frequently placed alongside the inner rail1 as in ,figs4 #cj to #cc1 to check the tendency of the engine to leave the rails and run in a straight line4 ,for the bull-head road a special chair is used1 which holds both the running-rail and the check-rail1 as shown on the sketch1 the rails being kept the proper distance apart by the web portion in the centre1 which forms part of the casting4 ,for the flange railroad1 check-rails are sometimes made of strong angle irons placed against the flange of the running-rail1 and bolted to the transverse sleepers4 ,this method #ec is not nearly so strong or efficient as the arrangement shown on ,fig4 #cc1 with a cast-iron distance-block about six inches long1 placed between the running-rail and check-rail1 and all tied together with a strong through bolt4 ,a bolt-hole is punched in the edge of the flange of check-rail1 and a crab bolt and clip holds the two rails on the sleeper4 ,the cast-iron distance-blocks are placed just outside the sleeper1 so as not to interfere with the holding-down bolt4 ,doubtless these guard rails do good service1 but if the leading wheels of the engine have sharp or worn flanges there is the possibility that the wheel1 pressing against the high rail1 may mount the rail1 and throw the train off the line4 ,a more secure method is to place the guard outside the high rail1 as in ,figs4 #cd to #ch4 ,this can be done by securing a strong continuous longitudinal timber to the cross-sleepers--or to the cross-girders in the case of a girder bridge--with its outer or striking edge protected with a fairly heavy angle iron4 ,the top of this outside guard above the rail level may be three inches or more1 according to the height of any hanging spring1 or portion of brake apparatus belonging to the rolling-stock4 ,the distance between the striking-face of the guard and the inside of head of rail should be about #e inches1 or such width that before the flange of the wheel can mount on the top of the rail1 the face of the wheel-tyre will be brought into contact with the striking-face of the outside guard1 and thus effectually prevent the wheel leaving the rail4 ,the sketches show some of the types applicable to the chair road1 and to the flange railroad4 ,in ,figs4 #cd1 #ce1 and #cg1 the outside brackets are of heavy angle iron cut off in lengths to correspond to the width of the sleeper4 ,in ,fig4 #cf the cast-iron chair is lengthened1 and has an end bracket to support the guard timber4 ,in ,fig4 #cg a hard wood bolster is fastened on the top of each sleeper1 and on this is placed the continuous guard timber4 ,this method of increased security is frequently adopted on girder bridges and long iron viaducts which are on the straight1 and in such cases it is usual to place the guards outside each of the rails forming the track4 ,the introduction of bogie engines and bogie carriages has conduced largely to the safe working of the train-service over the curved portions of many of our home railways1 as well as to the economy in the wear and tear of permanent way and rolling-stock4 ,the action of long rigid wheel-base vehicles passing round sharp curves is #ed detrimental to all the parts brought into contact4 ,not only is there the constant tendency to mount the rails1 and spread the gauge1 but the tiny shreds of steel scattered all along close to the rail--particles ground off the rails1 or off the wheel-tyres1 or both--testify to useless wear1 unnecessary friction1 and great waste of motive-power4 ,the gradual increase of accommodation and conveniences in the carriage stock of ,european railways led to the gradual increase in the length of the vehicles4 ,the six-wheeled carriage superseded the four-wheeled carriage1 on account of its increased steadiness when running1 but the introduction of long sleeping-cars1 dining-cars1 and corridor cars necessitated some better wheel arrangement than the ordinary six-wheel type could supply4 ,the six wheels had been spread as far apart as was admissible for carrying weight and passing round curves1 and something had to be done to meet the demand for still longer carriages4 ,many of the six-wheeled carriages at present running on our own home lines have a fixed wheel-base as long as #bb feet1 and with this length the horn-plates must undergo a very considerable strain when adapting themselves for the passage round curves of small radius4 ,on a curve of #ae chains radius 7#iij feet7 a chord of #bb feet will have a versed sine or offset of #jgc of an inch1 and on a curve of #aj chains radius 7#ffj feet7 an offset of #aaj of an inch4 ,fortunately1 curves of the above small radius are not very numerous on our main lines2 but wherever they do occur1 the conflict between the long fixed wheel-base rolling-stock and the permanent way must be very severe to both4 ,several descriptions of eight-wheeled carriages have been tried on our home lines2 but the system which is now most in favour is the ordinary bogie truck1 which has been in use for so many years on all ,american railways4 ,a bogie truck is really a short carriage frame complete in itself1 with its wheels1 springs1 and brake appliances1 and is attached to the under side of the carriage body by a central pivot1 round which the truck can swivel or rotate sufficiently to adapt itself to the curved portions of the line4 ,with a bogie truck at each end of a long carriage1 the vehicle will pass as easily round curves as on the straight line1 side pressure1 or grinding against the rails1 is obviated1 and friction is reduced to a minimum4 ,the bogie truck may consist of four wheels or six wheels1 according to the length and weight of the carriage to be supported4 ,illustration3 ,fig4 #ci1 #dj1 #da1 #db ,figs4 #ci1 #dj1 and #da show sketch elevation1 plan1 and transverse #ef section of one pattern of four-wheel bogie truck largely adopted in ,american carriage stock1 and although there are other types varying in detail1 the general principle remains the same in all4 ,the diagram sketch 7,fig4 #db7 represents the two bogie trucks slightly swivelled to adapt themselves to the curve round which the carriage is supposed to be passing4 ,for carriage or waggon stock with an independent bogie truck at each end1 the central pivot and swivelling motion supply all the freedom that is requisite2 but for locomotives it is necessary to provide for lateral as well as for swivelling movement4 ,the driving and trailing wheels--and sometimes one or two other pairs of wheels--work rigidly in the frames1 and as the normal position of the centre of the bogie truck must be in the centre line of the engine for the straight line1 it is evident that some appliance must be introduced to allow the truck to move laterally when the engine has to traverse the curves4 ,figs4 #dc1 #dd1 and #de give sketch elevation1 plan1 and transverse section of a swing-link bogie truck as applied to an ordinary ,american locomotive4 ,its recommendations are its simplicity1 its efficiency1 and its accessibility for inspection and lubrication4 ,the swing-links1 which provide for the lateral movement1 are direct acting1 and do not require any side springs of steel or indiarubber4 ,all the principal parts of the bogie are visible and not mysteriously cased in with plate-iron boxwork4 ,in the sketches several minor details are purposely omitted and only sufficient particulars shown to explain the method of working4 ,the under side of the upper centre plate which carries the cylinder castings and smoke-box end of boiler is cup-shaped1 and fits into an annular groove or channel in the lower centre plate1 which is suspended from the framework of the truck by the four swinging links4 ,practically the entire carrying and swivelling work of the bogie truck is effected by the annular-groove casting moving round the cup-shaped casting1 and the centre pin is merely passed down through each to guard against the risk of the one lifting out of the other from sudden shock or derailment4 ,illustration3 ,fig4 #dc1 #dd1 #de1 #df ,the lateral movement of the truck is obtained by means of the four swing-links4 ,when the engine is on the straight road the centre line of the bogie is on the centre line of the engine1 and the links hang in the positions shown on the sketch1 inclined towards the centre2 but #eh upon entering a curve they come into play1 and allow the truck to move out sideways to the right or left1 according to the direction of the curve1 the one pair of links assuming a flatter angle1 while the other pair approach nearer to the vertical1 the extent of side movement depending on the amount of the curvature4 ,when the engine enters the straight line again1 the bogie truck resumes its central position4 ,the ,bissell truck consists of one pair of wheels connected to a triangular framework1 as shown in ,fig4 #df4 ,the axle-boxes are attached to the side of the triangle which lies parallel to the axle1 the other two sides terminate in a circular ring which works round a centre pin fixed to the engine4 ,these two sides are practically the radii of a given circle1 and permit a large amount of lateral movement1 which can be controlled by placing suitable stop-pieces to limit the side play to the extent desired4 ,radial axle-boxes have been tried on the engines of some railways4 ,in the best types the opposite boxes are braced together by a diaphragm1 or plate-iron framework1 to ensure that both boxes work together4 ,the curved faces of the horn-blocks1 in which the radial axle-boxes slide1 are struck from a centre taken at some point to the rear of the normal centre line of the axle1 and stops are placed at proper distances to control the extent of lateral movement4 ,although the advocates of radial axle-boxes may urge some points in their favour1 there are few engineers1 if any1 amongst those who have had practical experience of both systems1 who would for a moment claim for the radial axle-box anything but a modicum of the many advantages obtained by the four-wheeled bogie truck4 ,as one of the principal functions of a four-wheeled bogie truck for an engine is to act as a path-finder1 or guide1 to the other wheels which constitute the fixed or rigid wheel-base portion of the machine1 it follows1 therefore1 that the full benefit of the bogie truck can only be obtained when it is placed at the leading1 or front1 end of the engine4 ,in this position the bogie1 with its swivelling arrangement and smaller weights1 is the first to pass over the rails1 and in doing so shapes the course and prepares the way for the easy running of the heavier wheel weights which have to follow4 ,when the bogie truck is placed at the rear end of the engine1 its action is restricted to affording lateral movement only1 and the driving and coupled wheels have to force or pound themselves round the curves in a jerky1 irregular manner1 as compared to their smooth running when following #ei the leading or guiding influence of a bogie truck in front4 ,the wheel-base of a four-wheeled bogie truck for an engine should always be greater than the gauge of the line over which the bogie has to travel ,on the #d feet #h inch gauge some of the best results have been obtained with bogies having wheel-bases varying from #f feet to #g feet4 ,where the wheel-centres have been less than #f feet1 the running has been found to be much less steady than with the wider spacing2 and where the wheel-base is not more than the gauge1 there is a tendency for the bogie to catch1 or lock1 when passing round sharp curves4 ,,chapter ,,ii4 #fj ,works of construction3 ,earthworks1 ,culverts1 ,bridges1 ,foundations1 ,screw piles1 ,cylinders1 ,caissons1 ,retaining walls1 and ,tunnels4 ,earthworks4--,under this heading may be classified cuttings and embankments of earth1 clay1 gravel1 and rock4 ,when setting out a line and adjusting the gradients1 an endeavour is usually made to so balance the earthworks that the amount obtained from the cuttings may be sufficient to form the embankments4 ,with care1 this may be effected to a considerable extent2 but there will be places where the material from cutting is unavoidably in excess1 and others where the cuttings are too small1 or contain good rock1 or gravel1 which can be more advantageously used for building and ballasting purposes than for ordinary embankment filling4 ,or there may be a large cutting which will provide enough material to form three or four of the adjoining embankments2 but the distance1 or lead1 as it is termed1 to the far embankment may be so long1 and1 perhaps1 on a rising gradient1 that it would be cheaper to run the surplus cutting to spoil1 and borrow other material for the far embankment from side cutting or elsewhere4 ,a long lead adds materially to the cost and time of forming an embankment1 as it not only necessitates a considerable length of service1 or temporary permanent way1 but also occupies much time in the haulage of the earth waggons4 ,for distances of half a mile and upwards1 a small locomotive is more suitable than horses for conveying the waggons4 ,to run to spoil is the term applied to such of the material from a cutting which1 not being required or utilized in the formation of the line embankments1 is removed and tipped into mounds1 or spoil-banks1 in some one or more convenient sites near the mouth of the cutting4 ,sometimes the surplus material is disposed of by increasing the width of the embankments4 ,material excavated in a #fa tunnel1 and hoisted through the shafts to the upper surface1 has to be deposited in spoil-banks along the centre line of the tunnel4 ,to borrow material to form an embankment is the term used when the earthwork filling is not obtained from the cuttings on the line4 ,this borrowing is generally done by excavating a trench on each side of the line1 of such width and depth as will supply sufficient material to form the embankment4 ,fig4 #dg gives an example of an embankment thus made from side cutting4 ,in some cases a piece of high ground adjacent to the embankment can be utilized for obtaining a portion1 or even the whole of the filling4 ,increased material is sometimes obtained by widening the cutting1 or flattening the slopes1 or both4 ,the degree of slope of a railway cutting must be regulated by the nature of the material excavated4 ,a slope of #a to #a1 which gives for every foot of vertical height a width of one foot #f inches of horizontal base1 as in ,fig4 #dh1 is usually adopted for cuttings in ordinary earth1 good clay1 sand1 or gravel4 ,there are some descriptions of strong clay and marl which will stand at a steeper slope1 even at #a to #a2 but1 on the other hand1 there are some kinds of clay which must ultimately be taken out to #b to #a1 and even #c to #a4 ,it frequently occurs that the slopes of a clay cutting1 taken out to #a to #a1 appear to stand well for a time1 but after exposure to the frost and rain of one or two seasons1 the material becomes loosened1 and forms into slipping masses1 which slide down on to the line1 stopping all traffic1 and have to be cleared away before train operations can be resumed4 ,cuttings through solid rock may be taken out to a slope of to #a1 as shown in ,fig4 #di1 provided the material is compact1 and there is not too great a dip in the strata or rock-beds4 ,where the rock-beds lie at a considerable angle1 the slope on the high side will have to be made flatter than the slope required on the low side1 as shown in ,fig4 #ej1 and great care must be taken to remove from the high side all loose or disconnected pieces of rock which might come away and slide down on to the line4 ,illustration3 ,fig4 #dg1 #dh1 #di1 #ej1 #ea ,strong dry chalk will generally stand at a slope of 1 or to #a1 but when wet and mixed with flints it will be necessary to increase the slope to not less than to #a4 ,where the rock is loose and disintegrated1 a slope of not less than or to #a will be required1 #fc and at many points there will be detached threatening masses of rotten rock which must be cleared away to a much flatter slope for safety4 ,in cuttings of this description it is frequently found necessary to clear out a portion of the loose pieces of the lower cavities and build in their place a facework of masonry to support the superincumbent rock4 ,springs of water rising in the rock1 or running over any part of the rock slopes1 must be properly provided for1 and conducted to the nearest channel4 ,they should be carefully watched during the winter season1 when the frost1 acting on the water penetrating the crevices1 splits and separates large pieces which were previously firm and secure4 ,instances will occur where a cutting has to be made through a thick bed of rock and several feet of soft loose strata underneath4 ,the effect of forming a cutting through the soft strata is to induce the heavy bed of rock above to squeeze or force out the softer material below1 and unless proper means were taken to avert such a disturbance1 the entire cutting would have to be excavated to a very flat slope4 ,the method adopted in such a case is to build strong face-walls of masonry1 brickwork1 or concrete1 underneath the rock1 as shown in ,fig4 #ea1 with strong inverts placed at short distances4 ,suitable arrangements must be made to take away the drainage water which will collect at the back of the walls1 and weeping-holes or outlets must be left in the lower part of the walls to convey the water into the water-tables on the line4 ,where there is a depth of earth cutting on the top of the rock1 the earth should be cut away so as to leave a bench or space of #c or #d feet between the edge of the rock cutting and the foot of the earth slopes1 as shown on ,fig4 #eb4 ,in cases of shelving rock1 with earth or clay on the top1 as shown in ,fig4 #ec1 it is frequently found necessary to remove the whole of the clay on the high side to prevent the possibility of its sliding off the rock on to the line below4 ,illustration3 ,fig4 #eb1 #ec1 #ed1 #ee1 #ef ,in large cuttings it is usual to push forward a gullet of sufficient width for one or two lines of waggons1 as shown in ,fig4 #ed4 ,when this has advanced some distance1 strong planks or half balks of timber are placed across the gullet1 and the sides or wings of the cutting can be excavated1 the material wheeled to the gullet1 and tipped from the barrows into the waggons beneath4 ,by this arrangement the work can be carried on very expeditiously1 as one set of men can be engaged #fe advancing the gullet and laying the track1 while others are following up and taking down the sides4 ,a large number of waggons can thus be filled in a day1 and a small locomotive kept fully employed4 ,occasions will arise where the material from a large cutting1 situate on a continuous gradient1 as in ,fig4 #ee1 has to be carried in both directions to embankment4 ,in wet weather1 or if the cutting is at all wet1 it would be almost1 if not quite1 impossible to carry on the excavation at the upper end to the proper formation level4 ,the water would collect at the lower level1 and not having any means of escape1 except by pumping1 would stop the work4 ,in such a case the best way is to take out the cutting at the upper end to a slight rising gradient1 as shown in the sketch1 sufficient to carry away all water1 and afterwards take out the lower portion in the working from the other end of the cutting4 ,cases will arise where it will be necessary to make a shallow cutting through boggy peaty ground4 ,if the boggy material be very soft1 and its thickness from the formation level to the solid ground below be not great1 it may be advisable to remove this extra thickness down to the hard lower bed1 and fill in up to formation level with strong material4 ,if1 however1 the bog or peat be too thick to justify its entire removal1 it should be excavated say down to two feet below formation level1 and a thick layer of branches of trees and strong brushwood closely laid and packed the full width of the road-bed4 ,on this preparatory foundation must be placed good clean ballast to carry the permanent way4 ,two or three extra sleepers should be allowed to the rail length1 and in some instances it will be necessary to introduce two1 or even four1 rows of strong longitudinal timbers--half balks--under the transverse sleepers4 ,the object of all this extra timber is to obtain a large increase of bearing area on the soft yielding surface of the boggy material4 ,notwithstanding these special precautions1 the trackway will sink down a little during the passage of an engine or train1 but will generally return to its former level4 ,good side drains or water-tables should be formed at each side of the cutting to take away all rain and surface water4 ,in all cuttings it is desirable to have the line of formation on a slight gradient1 sufficient to carry away all rain water or spring water which may be collected in the water-tables2 but more #ff particularly so is this necessary in a rock cutting1 where the material1 being non-absorbent as compared with earth or gravel1 requires that all drainage must be carried away to the mouth of the cutting4 ,in carrying out railway embankments and road approaches1 it is usual to form the sides to a slope of #a to #a1 as shown on ,fig4 #ef4 ,occasionally the cuttings produce material which might stand at a rather steeper slope1 but considering the effects which might afterwards be produced by heavy rains falling on the sides1 it is more prudent to adopt the flatter slope of #a to #a4 ,some descriptions of clay will not stand at the above slope1 but require a slope of #b to #a1 or even #c to #a4 ,when proceeding with the earthworks1 it is customary to first remove and lay aside a layer1 say #i inches in depth1 of soil and earth from the seat of the embankments and top widths of the cuttings1 to be used afterwards in soiling the trimmed and finished slopes of the cuttings and embankments4 ,this soil being removed1 the actual work of the excavation can be commenced4 ,the working longitudinal section will give all the necessary particulars as to position of the mouths of the cuttings and the depths at the various chain-pegs1 and the top widths of the cuttings can be ascertained by calculation1 if on even ground1 or from the cross-sections if on side-lying ground1 according as the material may be earth1 clay1 or rock4 ,for facility of carrying on the works1 reliable bench marks1 or reduced level stations1 must be established at convenient distances along the route of the line1 and from these and the fixed chain-pegs the correct line of formation level can be checked from time to time as the work proceeds4 ,for ordinary earth or clay cuttings1 the usual tools are picks and iron crow-bars for loosening1 or getting the material1 and shovels for filling into barrows1 carts1 or waggons4 ,for heavy earthworks1 steam excavators are now largely employed4 ,great improvements have been made in this class of machinery1 in the way of perfecting the method of excavating lifting1 and filling the material into the earth-waggons4 ,in nearly all rock cuttings the greater portion of the material has to be taken out1 or loosened1 by blasting with gunpowder1 dynamite1 or other explosive4 ,the number and extent of the charges will depend upon the nature of the rock and its stratification1 and also on its position #fg as regards proximity to buildings or residential property4 ,where the rock is loose1 or disintegrated1 the pieces can generally be readily separated by picks and bars without having to resort to any great extent of blasting4 ,illustration3 ,fig4 #eg1 #eh1 #ei1 #fj1 #fa1 #fb1 #fc1 #fd1 #fe1 #ff ,the first of the material excavated in the cuttings is generally conveyed in wheelbarrows to form the commencement of the adjoining embankments4 ,when the wheeling distance becomes too far for economical barrow work1 ordinary carts or three-wheeled carts1 sometimes termed dobbin carts1 are brought into operation where the cuttings and embankments are light2 but where the earthwork is heavy1 both in excavation and filling1 a service or temporary road of light rails and sleepers is usually laid down to carry strong tip earth-waggons4 ,for moderate distances these waggons are hauled by horses1 but for distances over three-eighths of a mile a small locomotive is more speedy and economical4 ,fig4 #eg shows one form of dobbin cart2 the wheels are made with good broad tyres1 so as not to sink too deep into the soft ground1 and the body being attached to the framework by a pivot or trunnion on each side1 can be readily tilted over1 and the earth tipped out1 by releasing the holding-down catch4 ,where the ground is soft and wet1 or of a very loose sandy nature1 the work of hauling these dobbin carts is very heavy on the horses1 and in such cases it soon becomes an advantage to lay down a service road of rails and sleepers4 ,this service road is formed of light rails manufactured for the purpose1 or old1 worn rails no longer fit for main-line work1 spiked down on to rough transverse wooden sleepers4 ,the end of the embankment in course of formation1 and where the earth is being tipped1 is termed the tip head4 ,two or more roads are required at the tip head to form the embankment to its full width4 ,fig4 #eh gives a sketch plan of a service road near the tip head4 ,the width is shown as for a double line4 ,the earth-waggons are hauled along the line from the excavation1 and brought to a stand at the point ,a4 ,if a locomotive has drawn the waggons1 it is then detached1 moved forward1 and shunted back into the siding ,,bc4 ,a horse accustomed to tipping then takes one full waggon at a time over one or other of the two turn-outs1 ,,def or ,,dgh1 to the tip head1 sufficient impetus being given to the waggon to run the front wheels off the ends of rails on to cross-sleepers laid close1 with a steep rise1 and backed up with #fi earth4 ,this suddenly checks the frame of the waggon1 and the body containing the excavated material revolves on its trunnion1 tilts up1 and shoots out the material well forward1 so that the man in charge of the tip head1 who also knocks up the 8tail-board catch10 is able to level off the filling without assistance4 ,the empty waggon is then hauled back1 and turned into the siding ,,bc1 and another full waggon taken forward and tipped1 until all the waggons of the rake are emptied4 ,ten waggons generally form a rake when the work is pushed forward vigorously1 each waggon holding about three tons4 ,the tip head horse pulls the waggon by a trace-chain having a spring catch at the end1 by which the driver releases the horse at the right moment4 ,it is very important that this spring catch should be kept in good order1 because occasionally too much impetus is given to a waggon1 which1 running over the tip head down the slope1 would drag the horse with it if the spring catch did not act properly4 ,good firm foothold must be provided for the tipping horse4 ,the tip head should never be carried across culverts or bridges until they have been well backed up1 and protected by a thick covering of earth or clay1 wheeled in with barrows to an equal height on each side of the masonry1 so as to prevent undue side pressure4 ,fig4 #ei gives a sketch of one form of end-tipping waggon4 ,in some cases the wheels are made of cast-iron1 but as these are readily broken during the rough handling to which earth waggons are exposed1 it is questionable whether the light wrought-iron wheels1 with light steel tyres1 used on some works1 are not more economical in the long run4 ,the framework and body are made of strong undressed timber1 well bound and bolted together4 ,the tail-board catch keeps the body of the waggon in its proper horizontal position while loading or running1 but when released leaves the body free to tilt up1 and to revolve on the front trunnion by means of the circular clip ,a4 ,the same principle is also applied to side-tipping waggons which are used for the widening of embankments1 or formation of platforms and loading-banks4 ,the permanent way of these service roads is generally made as simple as possible4 ,a pair of movable rails are used instead of switches1 as shown in ,fig4 #fj4 ,these rails are linked together by iron tie-rods1 and pulled or pushed over into position for one or other of the roads #gj by means of the handle at ,a4 ,a stout iron pin1 or iron clamping-plate1 serves to retain the rails in position during the passing of the waggons4 ,in a similar manner1 a short rail working on a pin1 or pivot1 is made to answer the purpose of an ordinary crossing4 ,the rails are laid complete and continuous for the one road1 and for the second road the outer rail is laid sufficiently high to cross over the rail of the first road4 ,a piece of rail is then secured by a centre pin1 or pivot1 to the cross-sleeper1 as shown on ,fig4 #fa4 ,this pivoted rail is pulled over into the position shown by the dotted lines1 to allow the passage of waggons on the one road1 or pulled across to the end of rail at ,b1 for waggons to pass on or off the other road4 ,in the latter case an iron pin or clamp serves to keep the pivoted rail in position4 ,as these service roads are merely laid down on the soft loose material brought forward for filling1 they require constant packing and lifting to prevent them working into depressions1 which might cause the waggons to leave the rails4 ,to indicate the height of the embankment filling1 strong stakes or poles must be firmly set in the ground at each chain-peg4 ,on each of these poles two cross-bars must be fixed1 the lower one placed to the correct height of the embankment1 and the upper one to show the amount allowed for subsidence4 ,the excavated material1 as brought from the cuttings1 is in a soft1 loose condition1 and an allowance must be made for its settlement1 or subsidence1 as the embankment becomes consolidated4 ,this allowance will1 of course1 depend on the height of the embankment and the quality of the material1 but for ordinary earth and clay it is customary to allow about one inch to the foot of height1 which is equal to about #h per cent4 ,when forming embankments over very side-lying ground1 it is necessary to cut steps in the sloping surface on which the filling material has to be placed1 as shown in ,fig4 #fb4 ,these steps give a hold to the new earthwork1 and check the tendency to slide down the hillside4 ,embankments have frequently to be carried over ground which is low1 soft1 and wet1 but not boggy4 ,if the culverts and drains are sufficiently large1 and properly arranged1 these places are not likely to cause much future trouble4 ,for a thoroughly soft deep bog1 however1 it is most difficult to make any accurate calculation as to the amount of embankment filling which #ga will be necessary to form a permanent foundation for the line2 and the construction of a high heavy embankment across such a place is one of those undertakings which every engineer is most anxious to avoid4 ,a large quantity of material may be tipped into the bog1 and seem to stand fairly well for a time1 and then suddenly disappear altogether4 ,more material has to be brought forward1 and will most likely disappear in a similar manner4 ,the filling material being heavier than the bog on to which it is thrown1 falls through1 and displacing the soft semi-liquid matter1 continues to sink down lower and lower until it is stopped by a harder stratum underneath4 ,in a measure the operation somewhat resembles the tipping of earth into a lake2 the material will go down until it meets with a solid bottom1 and in going down it assumes its own natural slope1 and forms for itself a width of base corresponding to its height4 ,it will be readily understood what an enormous amount of filling material will be swallowed up in following out such a process4 ,on a very soft bog1 say #bj feet in depth1 over which an embankment #bj feet high has to be formed1 the extent of the actual earthwork filling will very probably closely approach the outline shown in ,fig4 #fc4 ,the upper portion1 ,,abcd1 representing the embankment proper1 will contain about #acc cube yards to the yard forward1 whereas the lower portion1 ,,cdef1 which has displaced the soft boggy matter1 will contain about #bff cube yards to the yard forward1 or1 in other words1 the filling which is out of sight will be double the filling which is in view above the section ground line4 ,apart from the large amount of filling consumed in forming this semi-artificial island1 the progress of the work itself is very perplexing4 ,a long length of the bank may have been raised again1 once or twice1 to the proper height1 and may have carried rails and earth-waggons for some weeks1 and then sink all at once several feet4 ,the sinking1 too1 may not be uniform1 but may produce fissures1 depressions1 and separation of the earthwork which will necessitate much care when bringing forward fresh filling material4 ,the bog may not be of the same consistency throughout1 there may be some layers of harder material1 such as imbedded trunks of trees1 and these may sustain the filling for a time1 and then yield under the increasing weight of the superincumbent mass4 ,even when the embankment is finished throughout1 and shows no sign of sinking1 it should be very carefully watched for a long time for any indication of further #gb movement4 ,when the bulk of the material has been taken out of an earth or clay cutting1 the work of trimming the slopes should be put in hand1 so that any surplus left on the wings1 or sides1 may be removed1 and carried away before stopping the earth-waggons4 ,the angle of slope having been decided1 a battering rule of light wooden boards is made to correspond to the slope1 and in form similar to that shown in ,fig4 #fd4 ,a plumb-bob is suspended from a fixed point1 ,a2 the lower end1 ,b1 is then held against a peg or mark which indicates the correct level and width of the cutting at the place1 and the upper end1 ,c1 is raised or lowered until the plumb-bob string coincides with the vertical line marked on the rule from ,a to ,d1 and the plumb-bob rests steadily in the space cut for it at ,d4 ,with this battering rule a length of seven or eight feet1 according to the size of the rule1 is first trimmed to the correct slope1 and by continuing the application of the rule up the side1 a correct slope line is obtained from bottom to top of slope at that place4 ,by repeating the process at convenient distances along the cutting1 a series of correct slope lines are obtained1 and the intermediate space can readily be trimmed to correspond4 ,the same form of battering rule and method of working is applicable for trimming the slopes of the embankments4 ,when the slopes of the cuttings and embankments have been trimmed1 vegetable soil1 which has been laid aside1 or reserved as previously described1 should then be spread evenly over the slopes to the uniform thickness of not less than four inches1 and the whole sown with good grass seeds to form a strong sward4 ,the trimming1 soiling1 and sowing of the slopes not only gives a more finished appearance to the earthworks1 but the strong grass1 when once well grown1 binds the surface together1 and helps to resist the injurious effects of heavy rains and melting snow4 ,there are many places abroad where a neat finish to the earthworks is considered quite a secondary matter1 or where it would be difficult to obtain suitable soil to spread on the slopes4 ,the earthworks are hurried forward to allow the iron highway to be laid down as quickly as possible1 the slopes of the cuttings and embankments are only roughly trimmed1 and nature is left to supply such grass or vegetation #gc as may spring up1 or be self-sown4 ,the fencing in of a line of railway serves the double purpose of defining the boundary of the company's property1 and of forming a barrier for the prevention of trespass of persons and animals on to the line4 ,for our home lines1 fencing is compulsory1 and the same obligation exists on many foreign railways4 ,in our colonies1 and out in the far ,west of the ,united ,states1 and in newly opened out countries1 fencing1 except near towns and villages1 is rather the exception than the rule2 people and animals roam at will from one side of the railway to the other wherever they find a convenient crossing place1 and the cowcatcher of the engine has to be depended upon for throwing aside any animal which may be standing1 or resting1 on the line of rails at the passing of a train4 ,the description of fence will be influenced by the locality1 and the materials conveniently obtainable4 ,where stone is plentiful1 perhaps brought forward out of the cuttings1 and labour cheap1 a masonry wall will be found a most suitable permanent fence4 ,any fence to be of service should not be less than four feet high4 ,a wooden post and rail fence is much in favour in some districts1 the posts being firmly set or driven into the ground1 and four or five stout bars nailed on to1 or set into1 the upright posts4 ,this fencing does not last very long1 the pieces are small in size1 and soon fail from decay4 ,quick or hawthorn hedges1 when fully grown1 make a good fence1 but require careful attention to prevent gaps being made by roving cattle4 ,they also require constant trimming and cutting4 ,the quicks are generally planted in a mound formed by cutting a continuous ditch1 or gripe1 as shown in ,fig4 #fe4 ,the ditch serves as a drain to take away water running down the slopes of the embankments1 small openings in the mounds1 or drain pipes through them1 forming leaders to conduct the water to the ditch or gripe4 ,the outer edge of the ditch represents the boundary of the railway property1 unless specially arranged otherwise4 ,galvanized iron-steel wire fencing1 if not made too light1 is strong and durable1 and very easily kept in order4 ,the wires may be secured to strong wooden posts1 which should be creosoted1 and not placed too far apart1 or to iron posts or standards of angle iron or tee-iron section4 ,the straining-posts1 whether of iron #gd or timber1 must be stronger than the intermediate posts1 firmly fixed into the ground1 and well stayed1 to withstand the pulling and tightening of the wires4 ,there are many places where a quick fence would not grow1 and where the ground is too soft to carry a wall4 ,in such cases a good galvanized-wire fencing will fulfil all requirements4 ,the strand wire is better than the plain wire1 as its method of manufacture necessitates the use of a superior material1 and it is easier to straighten and keep in good order4 ,an extra strong fence is often made of six1 eight1 or more rows of round rod-iron secured to wrought-iron uprights of bar-iron or tee-iron4 ,in hot countries abroad an excellent fence is obtained by planting a species of cactus or aloe in a similar manner to the quick fences at home1 and as shown in ,fig4 #ff4 ,these cactus plants are readily obtained1 are very hardy and quick in growth1 and with their large spike-shaped leaves form such an almost impenetrable barrier that few animals will attempt to pass4 ,road approaches to bridges over or under the line1 or to public road level crossings1 may be fenced in the same manner as the line proper4 ,if quicks are adopted1 it will be necessary to put up a light wooden fence also to protect the young plants until they are well grown4 ,near towns and villages it is frequently found advisable to adopt a specially strong wooden fence1 or close-boarded fence1 where the approach is an embankment1 and too newly made to carry a wall4 ,gates for farm or occupation level crossings may be made of wood or iron4 ,as a rule1 iron gates are preferred1 as they can be supplied at the same cost as wood1 and are very much more durable4 ,gates for public road level crossings have to be so placed that they will either close across the railway or across the road2 their length will therefore depend upon the width and angle of the road crossing4 ,it is better to make these gates of wood1 so that1 in the event of a train running through them1 there may be less risk of injury to life and rolling-stock than if they were made of iron4 ,for footpath crossings1 small gates1 wickets1 or stiles may be adopted of such form as may be found most suitable for the requirements4 ,culverts and ,drains4--,before proceeding with the formation of the embankments1 it is necessary to construct the culverts and drains which will be covered over by the earthworks4 ,any existing drains which may be of too light a description must be reconstructed in a #ge more substantial manner4 ,it is a simple and comparatively inexpensive matter to rebuild a drain before the earth filling is brought forward1 but it is a costly work to open out an embankment1 and rebuild a culvert afterwards4 ,unless the seat of an embankment is well drained and kept free from the accumulation of running water1 the earthwork will be exposed to washing away of the lower layers1 and consequent subsidence4 ,each watercourse or open drain must be provided for either by a separate culvert of suitable size or1 as may be done in some cases1 by leading two or more watercourses into one1 and thus passing all through one culvert of ample capacity4 ,when fixing the sizes of the culverts they must not be limited to the normal flow of water1 but a large margin must be allowed sufficient to meet extraordinary floods4 ,the depth of the bed or invert of a culvert is a very important point4 ,if laid too high1 and the stream above should at any time deepen1 the high invert would check the flow of the water1 and would also incur the risk of being undermined and gradually carried away4 ,if1 on the other hand1 the invert be laid too low1 it will gradually silt up to the level of the stream-bed alongside1 and there will be so much of the culvert space lost for all practical purposes4 ,in cases when the invert of a culvert has to be laid at a special low depth to allow for future improvements in drainage1 it is advisable to give extra height from the invert to the crown1 or top1 so as to provide ample waterway in the event of any silting up in the mean time4 ,particular care should be taken when building the foundation of a culvert4 ,it has to be laid on the site of the watercourse1 or on a new channel which will ultimately form the watercourse1 and it should be built sufficiently deep into the ground to avert as far as possible the chance of water finding a course through below the foundation4 ,the invert may be of stone pitching or brick if the current is not rapid1 or liable to bring down stone boulders from its gravelly bed4 ,with a stream-course having considerable fall1 and which carries with it large stones1 roots of trees1 and other dbris1 the invert should consist of strong pitching1 composed of large-sized1 rough-dressed stones of hard1 durable quality1 capable of withstanding the pounding of the boulders brought down during floods4 ,a soft description of stone would be quite unsuitable for the invert of such a stream2 the pitching would wear away quickly1 break1 and become detached1 leaving #gf the foundation and side walls exposed to the cutting inroads of the water4 ,where large flat bedded stones or flags of tough quality can be obtained1 they form good covers1 or tops1 for culverts up to two feet in width4 ,they should have not less than nine inches bearing on the side walls1 and their contact edges should be fairly dressed1 so as to fit sufficiently close to prevent the embankment filling from falling through4 ,where the stream1 or run of water1 is very small1 strong earthenware pipes1 #i inches or #ab inches in diameter1 well bedded1 may be sufficient to carry away all the water likely to arise4 ,for small springs in low swampy ground1 dry stone drains may in many cases be used with advantage4 ,these are made by cutting a trench1 say two feet deep by twelve or eighteen inches wide1 in the seat of the embankment from side to side1 and filling it up with dry rubble stones1 not boulders1 hand-laid1 the upper layer placed on the flat to keep the earthwork as much as possible from filling in between the stones4 ,in soft boggy ground1 where the depth to a hard bottom is very considerable1 wooden culverts are frequently adopted4 ,although these cannot be classed as permanent structures1 still1 when they are made of sound well-creosoted timber1 and substantially put together1 they last for a number of years4 ,sometimes they are made cylindrical in section--a species of elongated cask with strong iron hoops every few feet4 ,others are rectangular in section1 made with two strongly trussed side frames connected and covered with cross-planking and longitudinal tie-planking on the top and bottom4 ,wooden culverts are seldom made of very large size1 rarely exceeding an opening of #c feet1 and it is considered preferable to use two of these culverts of moderate dimensions than one of large size4 ,figs4 #fg and #fh give sketches of wooden culverts of cylindrical and rectangular section1 and ,fig4 #fi of flag top culverts of #ab-;inch1 #ah-;inch1 and #b-;foot openings4 ,in masonry culverts the side walls are shown to be of rubble stonework1 but brickwork can be used instead1 provided the bricks are well burnt1 hard1 and capable of withstanding the action of the water4 ,illustration3 ,fig4 #fg1 #fh1 #fi1 #gj1 #ga ,in ,figs4 #gj and #ga are shown types of arch-top culverts of #d feet and #f feet span respectively4 ,the arch portion is shown to be of brick1 which1 as a rule1 is cheaper than stone rings1 which must be cut and #gh dressed to suit the small radius of the arch4 ,the side walls may be of brick of good quality4 ,occasionally they are built of concrete4 ,the wing walls may either be carried out in the direction of the stream1 as in the sketch of the #f-;foot culvert1 or they may be built transverse1 as shown on the #d-;foot culvert1 whichever arrangement is found to work in the best for the case in question4 ,for arch culverts on very steep side-lying ground it is better to build the arch-top in steps1 as shown in ,fig4 #gb1 instead of forming it parallel to the invert1 or slope1 of the stream-course4 ,the level portions of the arching give a better hold for the embankment than could be obtained on a long inclined surface of brickwork or masonry4 ,the writer has built a large number of culverts of this type for mountain streams on steep hillsides1 and has found them to prove satisfactory in every way4 ,in embankments alongside tidal rivers1 or across the corners of estuaries of the sea1 culverts have frequently to be so constructed that they will permit the passage of the drainage water from the land1 or high side1 without admitting the tidal water4 ,this can be arranged by placing at the lower end of the culvert close-fitting hinged-flap valves opening outwards4 ,when the tide has gone down the weight of the fresh1 or land1 water swings the flap-valve sufficiently open to allow of a free passage2 and1 on the other hand1 when the tide rises1 the pressure of the water against the face of the flap-valve keeps it tightly closed1 and prevents ingress of the salt water4 ,culverts are sometimes fitted with lifting-valves or doors1 which can be raised or lowered to serve irrigation purposes4 ,the door1 which works in guides1 is made sufficiently heavy to fall with its own weight1 and the raising is effected by means of a screwed suspension-rod working in a well-secured fixed nut4 ,in cases of soft or treacherous ground1 timber-piling or wide bed-courses of cement concrete are necessary to form firm foundations for culverts4 ,drains and streams which are intersected by a railway cutting have to be dealt with according to their size and their height above the finished rail level4 ,the water from a small drain or field spring may be conducted in pipes down the slope of the cutting into the water-table1 or side drain1 at formation level1 and will be thus carried away to the lower level at the entrance of the cutting4 ,in many cases streams can be diverted1 and the water led away to some #gi lower point without the necessity of actually crossing the railway4 ,with a large stream1 where it is essential that the water should be conveyed across the line and continue on its ordinary course1 it may be carried over in iron pipes or iron trough if there is ample headway1 or in iron syphon pipes where the height is not sufficient4 ,the iron pipes or trough can be supported on masonry or brick piers1 or cast-iron columns1 the height from the rails to the underside of the conduit being not less than that adopted for the over-line bridges4 ,occasionally the pipes can be carried across on an over-line bridge1 either by placing them under the roadway or on small brackets outside the parapet4 ,with the syphon arrangement the iron pipes must be laid down the slopes of the cutting and under the road-bed of the permanent way4 ,the pipes must be continuous1 strong1 and firmly connected at the joints to prevent leakage4 ,the inlet and outlet ends of the pipes should be securely built into receiving-tanks of masonry1 brickwork1 or concrete1 to ensure an uninterrupted flow of the stream1 and also to prevent any of the water from percolating through under the pipes and on to the railway4 ,as a precautionary measure1 it is well to place iron gratings some little distance in advance of the syphon pipes to intercept and collect any brushwood1 straw1 or other things which might be brought down with the stream4 ,fig4 #gc gives an example of the syphon arrangement as constructed with two cast-iron pipes placed side by side4 ,railway works carried out in cities and large towns1 whether they take the form of cuttings1 embankments1 arching1 or tunnels1 are certain to cause a very considerable disturbance of existing drains1 corporation sewers1 gas-pipes1 water-mains and underground telegraph wires4 ,some of these underground works may be so peculiar and complicated as to necessitate a slight deviation from the course originally intended for the line4 ,suitable provision will have to be made for each of the items interfered with by the railway1 and the substituted work must be carried out to the satisfaction of the constituted authorities within the municipal boundaries4 ,illustration3 ,fig4 #gb1 #gc ,bridges4--,amongst the many bridges and viaducts which have to be built during the making of a railway those constructed over rivers and waterways are generally the most important ,the bridging across any #ha navigable river or tidal water can only be effected in compliance with conditions imposed by the authorities controlling the navigation rights4 ,these conditions will place restrictions as to the number and distance apart of the piers1 as well as the height from high water level to the under side of the arches or girders4 ,for rivers having a constant traffic of sea-going vessels of large tonnage and lofty masts the authorities will demand great height or headway as well as large spans2 and if to this be added a deep water-way and bad foundations1 the work to be constructed becomes one of considerable magnitude4 ,the banks of the river must be carefully studied to find the most favourable point for crossing1 and in some cases it may be prudent to make a detour of two or three miles4 ,the crossing at a great height involves the construction of the approach lines at a great height also4 ,if the river is in a deep valley with high sloping sides the natural contour of the ground facilitates the formation of the approach lines2 but with a river on a low1 wide1 open plain1 inclined approach lines add enormously to the cost of construction1 as well as to the cost of permanent working4 ,if the number of sailing craft passing up and down the river be moderate1 and1 perhaps1 only passing at high water1 the authorities may permit a low-level viaduct with an opening bridge4 ,there are thus the two systems3 the high-level viaduct1 which allows trains to pass over and vessels to pass under at any and all times1 and the low-level viaduct with opening bridge1 which1 if open for vessels1 is closed for trains1 or vice vers4 ,every crossing of a navigable river will have to be considered and dealt with according to its own individual requirements4 ,an arrangement suitable for the one may not be admissible or prudent for the other4 ,a frequent and important train service might be much interfered with by an opening bridge1 and1 in a similar manner1 an opening bridge might cause much interruption and detention to the navigation of the vessels on the river4 ,illustration3 ,fig4 #gd1 #ge1 #gf1 #gg ,where a low-level viaduct with opening bridge can be adopted1 there will be a very great saving of expenditure2 and there are numbers of such viaducts in existence1 accommodating a large railway and river traffic without inconvenience4 ,even with a low-level viaduct the height from water-level to the under side of the girders of the various #hc fixed-spans will generally be sufficient for the passage of barges and small craft1 leaving the opening portion to be used by the larger vessels4 ,the principal openings for these large river viaducts are generally constructed for girders1 partly on account of the greater facility of girder work for large spans1 and also for the advantage of having one uniform height1 or headway1 from pier to pier4 ,for a high-level viaduct across a deep-water river1 the cost of the lofty piers forms a very important part of the undertaking4 ,each pier will require its own cofferdam1 caisson1 or other appliance for obtaining a suitable foundation4 ,the deeper the water1 the more costly the arrangement for foundation2 and the higher the pier to rail-level1 the greater the amount of material in the construction of the pier4 ,the consideration of these two points will at once show that it is very desirable not to have more of these costly piers than is actually necessary1 and in studying out the design it will be a question for calculation how far the spans may be increased so as to dispense with one or more piers4 ,in every work of this description there is a relative proportion between span and height1 which will give the most economical result from a cost point of view2 the proportion varying according to the depth of the water and description of ground for foundations4 ,an increase in the span will naturally necessitate an increase in the thickness of the pier2 but where a cofferdam1 or arrangement for putting in the foundations1 must in any case be made1 a small addition to its width may not necessarily form a large increase to its cost4 ,figs4 #gd1 #ge1 #gf1 and #gg are sketches of high-level railway viaducts which have been constructed with great height1 or headway1 to allow large vessels to pass under at all times without interruption4 ,this description of work is very costly1 not only in the deep-water foundations1 but also in the heavy scaffolding and appliances requisite for building piers and girders at such an elevation above the ground-level4 ,the hoisting of the material alone forms an important item where such vast number of pieces have to be lifted to a height of #hj1 #ij1 or #ajj feet4 ,illustration3 ,fig4 #gh1 #gi ,figs4 #gh and #gi are sketches of low-level viaducts constructed with one large opening span1 or swing-bridge1 for the passage of vessels4 ,the girders and roadway of such opening span are usually constructed #he as a compact framework1 which revolves on a centre placed in the middle of a circular roller path or species of turn-table4 ,the portions of the rotating opening bridge1 although not always the same length on each side of the centre-pin1 are generally very carefully balanced1 to preserve the equilibrium of the entire mass when swinging round for the passage of vessels4 ,to ensure stability in working1 and steadiness during heavy gales1 a liberal diameter should be given to the roller path of all swing-bridges having large span and great weight4 ,lattice1 or truss1 girders are preferable to plate girders for swing-bridges of considerable opening1 as they present less surface area to the action of the wind4 ,the opening and closing of these bridges is effected by wheel-gearing actuated by hydraulic1 manual1 or other motive-power4 ,the revolving machinery should be set solid and true1 well protected from the weather1 and1 at the same time1 readily accessible for constant inspection1 lubrication1 or repair4 ,figs4 #hj to #he are sketches of various types of railway bridges constructed for smaller openings across narrower rivers1 water-ways1 or canals4 ,fig4 #hj is an example of what is known as a bascule bridge4 ,this particular bridge is made in two halves1 meeting in the centre of the span1 the tail end of each half being provided with heavy counterweights to assist in opening or tilting up the bridge for the passage of vessels1 or lowering it down for railway traffic4 ,each half of the bridge swings on horizontal axles1 and the raising or lowering is effected by means of hand winches or other motive-power1 actuating wheel-gearing working into toothed vertical segments attached to the tail end of each half4 ,the same principle has also been applied to bridges having only one leaf to tilt up to clear the passage way4 ,railway bridges of this pattern are now very rarely adopted4 ,they have the great drawback that when raised to the vertical position1 a very large area is presented to the action of the wind1 and this defect might lead to very serious consequences in the case of a bridge situated in an exposed locality4 ,an open-work floor diminishes the wind area1 but a very large surface must necessarily remain4 ,illustration3 ,fig4 #hj1 #ha1 #hb1 #hc1 #hd1 #he ,fig4 #ha illustrates what is known as a traversing bridge4 ,in this case the width of the opening passage-way and the adjoining span are #hg made the same1 and the girders for the two spans are constructed in one continuous length4 ,by means of gearing attached to the fixed portion of the work1 the continuous length of girder1 with its roadway1 is first slightly raised or lowered1 and then drawn back on rollers sufficiently far to leave the opening span quite clear for the passage of vessels4 ,a reverse movement of the gearing causes the movable girders and roadway to travel back and return to their original position ready for the train traffic4 ,opening bridges are sometimes constructed on this system in cases where the level of the rails is only a few feet above the level of the water1 and where there is only one water opening1 and that not more than #bj to #cj feet wide4 ,in such bridges the movable portion is rolled back along iron rails1 or plates secured to masonry walls1 or strong pile-work4 ,this class of bridge is cumbersome1 slow to move1 and is now but very rarely adopted4 ,fig4 #hb shows a type of simple lift bridge1 of which there are but few examples remaining4 ,in this particular bridge the girders and roadway form a solid framework1 which rests on the abutments during the passage of the trains4 ,strong chains1 secured to the corners of the framework1 pass over large sheaves on the top of the iron standards1 and then round drums placed below the level of the rails1 and terminate by attachment to heavy counter-weights suspended in iron cylinders4 ,the counter-weights are adjusted to approximately balance the bridge1 so that a moderate power applied to the wheel-gearing on the drums is sufficient to raise the roadway to the required height4 ,this class of opening bridge is only suitable for the passage of barges and small craft without masts2 and it requires the re-adjustment of the counter-weights when the roadway varies in weight1 in consequence of rain or repairs4 ,figs4 #hc1 #hd1 and #he are sketches of small swing-bridges constructed for narrow waterways4 ,although differing in appearance1 they are all practically on the same principle1 with centre pin and roller path1 and are similar in general arrangement to the large-size-opening swing-bridges shown in ,figs4 #gh and #gi4 ,illustration3 ,fig4 #hf1 #hg1 #hh ,the swing-bridge arrangement is so simple in construction1 convenient for inspection1 and easy to maintain1 that where possible it is now generally adopted in preference to any other system4 ,the #hi weights on centre pin and roller path may be distributed as considered most expedient1 and by means of suitable appliances the weight may be altogether taken off the centre and rollers when the bridge is closed for the passage of trains4 ,there are many wide rivers which1 although not navigable in the ordinary acceptance of the term1 nevertheless require bridges of large spans to provide free waterway for the floating down of rafts of timber4 ,away in the high ground1 in the timber-growing districts1 trees are felled1 sawn or cut into long poles1 logs1 or scantlings1 and hauled to the banks of the river4 ,the timbers are then formed into large rafts of the most convenient form for floating down to the place of distribution or port for shipment4 ,even with old experienced floaters1 using their long sweeps in the most skilful manner1 it is difficult to take anything but a very irregular course down the stream4 ,under the most favourable circumstances one of these large rafts is an unwieldy1 awkward craft to manage2 but in a river full of twists and turns1 with reaches varying from comparative smooth water to miniature rapids1 the current carries the huge mass surging along1 and only a clear1 unobstructed channel will enable its navigation to be carried out with safety4 ,the presence of a pier in the main waterway might cause destruction to the rafts and loss of life to the men4 ,the vested interests in floating rights are tenaciously guarded1 and no new bridge would be sanctioned which would in any way interfere with the waterway or endanger the passage of rafts down the river4 ,bridges of this description are much less costly than those over deep water--navigable rivers4 ,excepting the large spans1 the rest of the work is comparatively simple4 ,the water is generally shallow1 and much reduced in quantity during the summer months4 ,good foundations can generally be obtained without going to any great depth4 ,the headway may be kept low1 or of such height as may best suit the purposes of the railway1 and be sufficiently well up out of the way of the floods which may take place from time to time on the river4 ,illustration3 ,fig4 #hi1 #ij ,fig4 #hf is a sketch of a bridge constructed over a river much used for rafting purposes4 ,the large span is over the main channel1 and the small spans are over a wide gravelly foreshore1 which is only covered with water during exceptionally high floods in the autumn or winter4 #ia ,no rafting can be carried on when the river is in flood2 the current would be too strong to permit of the raft being kept under control4 ,fig4 #hg is a sketch of a similar bridge where the river is confined to a regular channel between two sloping banks of strong clay4 ,fig4 #hh shows a bridge erected over a narrow rocky pass in the river4 ,the channel is hemmed in by the almost perpendicular sides of mountain granite1 there are no banks to overflow1 the flood waters cannot spread laterally1 however much they may increase in depth1 and with building-stone at hand in abundance1 and foundations formed in the solid rock1 the situation is one of the most favourable for a strong permanent bridge4 ,the cast-iron arch of #aej-;feet span has a graceful appearance1 and harmonizes well with the surrounding scenery4 ,a small masonry arch at each end of the bridge provides for communication along the banks of the river4 ,with rivers which are neither under the control of navigation authorities nor used for rafts of timber1 there is much greater freedom for the designing and carrying out of bridges or viaducts suitable for the actual physical conditions of the locality4 ,the headway will be guided only by the height of the railway to be carried across1 and by any flood-water levels which may affect the work4 ,the size of the spans will be regulated by the width of the river1 the depth of the water1 and the nature of the ground into which the piers have to be built4 ,for broad1 shallow rivers with good firm river-beds1 piers may be built at moderate cost1 and comparatively small spans adopted2 on the other hand1 with a broad deep river it will be better1 as previously explained1 to reduce the number of piers and increase the span4 ,in the one case1 for example1 a river #aej feet wide may be crossed with three spans and two piers in the shallow water1 as in ,fig4 #hi2 in the other it may be more prudent and economical to cross in one span1 without any intermediate pier1 as shown in ,fig4 #ij4 ,illustration3 ,fig4 #ia ,next in importance to the large bridges and viaducts over rivers are the viaducts which have to be constructed for the crossing of deep inland valleys4 ,the occurrence of one of these deep valleys between long lengths of average table-land renders necessary either a series of cuttings and falling gradients to get down to a low level1 or the erection of high-level works to continue onward the rail-level at the #ic height already attained4 ,a decision to adopt the latter course brings forward the consideration as to the method of carrying out the work4 ,to form a high embankment across such a valley would entail an enormous expenditure for earthwork1 and several openings1 or bridges1 would have to be made in the embankment for streams1 rivers1 and roadways4 ,instead1 therefore1 of making this part of the line entirely of embankment1 it is usual to carry the earthwork forward until the height is about #be or #cj feet1 and to form the remainder of the opening of arching1 as shown in ,fig4 #ia4 ,this arrangement is not only less costly than an embankment of such height1 but has also the great advantage that any or all of the arches are available for the passage of streams1 rivers1 roads1 and accommodation works4 ,the character of the work to be carried out in the construction of bridges or viaducts over rivers or valleys must greatly depend upon the description of materials at command4 ,where good building-stone is plentiful1 and the price of labour moderate1 works of masonry should be adopted as far as practicable4 ,brickwork is an excellent substitute for masonry1 provided that specially selected bricks are used for all facework1 or parts exposed to the weather4 ,for water-washed piers and abutments1 the lower portion should be faced with good hard stone4 ,illustration3 ,fig4 #ib ,bridges and viaducts consisting of arches of masonry or brickwork form the most substantial and permanent works of construction for railway purposes2 once properly built1 the expenditure on future maintenance or repairs is merely nominal4 ,for viaducts the span of the arching must be regulated by the height of the viaduct4 ,the greater the height the larger the span4 ,in one case #cj-;feet spans may be suitable1 whereas in another it may be more economical to introduce spans of #fj feet or more1 and so reduce the number of lofty piers4 ,from a cost point of view there is1 however1 a limit to the span of arching1 and1 except for special cases1 where expenditure is of secondary importance1 large spans are very rarely adopted4 ,arches of large spans1 no doubt1 have been built both in masonry and brickwork1 and have been a complete success in every way except expense4 ,unfortunately1 the quantity and weight of materials in arching1 and the corresponding cost1 increase very rapidly as the span increases1 #ie and for openings of more than #fj or #gj feet girder-work becomes much cheaper than arching4 ,figs4 #ib and #ic are examples of viaducts having piers of masonry1 with girders to carry the roadway4 ,in the one case the roadway is carried on the bottom flange of the girders1 and in the other on the top4 ,the latter arrangement affords greater facility for securely bracing the girders together1 while for the former it is claimed that the girders form a massive parapet1 which would serve as a protection in the event of an engine or vehicles leaving the rails4 ,in the early days of railways1 many large viaducts were constructed having masonry piers1 and timber trusses to carry the roadway4 ,much ingenuity was displayed in designing the trusses1 and in the introduction of cast-iron joint-shoes and wrought-iron bracings4 ,many of these wooden superstructures served well for several years1 but they were always exposed to the imminent risk of destruction from fire1 and however carefully the logs may have been selected1 the decay of the timber was only a question of time4 ,the deterioration of one piece was equivalent to the weakening of the entire truss1 and the renewal of any part was both difficult and costly4 ,the shrinkage of the timber1 and the working at the joints1 caused the trusses to deflect considerably under a passing load1 and although the actual strength of the structure may not have been much impaired1 the creaking and depression had anything but a reassuring effect4 ,timber superstructures for anything but small spans are rarely adopted now1 except for temporary works1 or on lines abroad1 where the transport on girder-work would be very costly1 and where good timber is very cheap and abundant4 ,even in the latter case the wooden superstructure is generally looked upon as a temporary expedient1 to be replaced at no very remote date with iron or steel girders1 when the materials can be conveyed over the entire completed line4 ,figs4 #id1 #ie1 and #if are sketches of three types of timber trusses as constructed in viaducts of several spans4 ,illustration3 ,fig4 #ic ,there are many localities1 especially abroad1 where suitable stone is most difficult to obtain1 and very expensive to work and convey4 ,in such cases it is compulsory to use as little of it as possible1 and to resort to iron or steel both for the girders and a large portion of the piers4 ,the piers may be made of cast-iron1 wrought-iron1 or steel1 #ig of suitable form and arrangement to ensure strength and stability4 ,not only must the piers be strong enough to carry the weight that may be brought upon them vertically1 but they must have sufficient width of base to ensure lateral steadiness4 ,the design should admit of facility of erection1 with a minimum of scaffolding1 and the pieces should be of convenient length and weight for transport4 ,the lower length of river piers1 or portion liable to be in contact with flood-water1 should be of solid masonry1 to resist the action of the water1 or of any dbris brought down by the current4 ,more than one fine viaduct has been swept away for want of due attention to the latter precaution4 ,fig4 #ig illustrates a type of pier composed of cast-iron columns1 well braced and stayed with wrought-iron4 ,the ends of the columns and all contact surfaces should be properly turned and faced by machinery to ensure true and perfect joints1 and the socketed ends should be turned and bored to fit closely4 ,the latter is important1 and if not carefully carried out1 a slight sliding movement of the flanges may take place1 and throw undue strain on the bolts4 ,fig4 #ih shows a very similar pier1 constructed entirely of wrought-iron or steel4 ,each of the above-described piers has a liberal amount of taper or batter1 both in the front and transverse elevation4 ,the size and number of the columns1 and the dimensions of the braces or stays1 will depend upon the height of the pier and the weights and strains to be sustained4 ,many important and lofty viaducts have been erected on this principle of iron piers springing from masonry foundations1 more particularly across deep rugged ravines abroad1 where iron piers offered the only practical1 substantial means of dealing with what appeared otherwise an impossibility4 ,illustration3 ,fig4 #id1 #ie1 #if1 #aja ,illustration3 ,fig4 #ig1 #ih ,illustration3 ,fig4 #ii ,illustration3 ,fig4 #ajj ,fig4 #ii is a sketch of the ,kinsua ,viaduct on the ,erie ,railway1 one of the highest railway viaducts in the ,united ,states4 ,in the transverse elevation the piers have a large amount of taper2 but in the front elevation they are vertical1 and of width to correspond to one of the small spans of the main girder4 ,this arrangement of long and wide base gives great stability to the pier4 ,the spans of the girders1 which are of the ordinary lattice type1 are not large1 being #fa feet for the clear spans1 and #ch feet #f inches for those over the piers4 ,the principal interest is in the great height and simplicity of the piers4 #ajb ,the rail-level over the top of the pier is #cja feet above the level of the water in the ,kinsua stream4 ,the width of this pier on the top is #aj feet 7for single line71 and the width at the bottom #ajc feet4 ,fig4 #ajj is a sketch of the ,loa ,viaduct on the ,antofagasta ,railway1 ,bolivia1 stated to be the highest railway viaduct in the world4 ,the arrangement of spans and piers is very similar to the ,kinsua ,viaduct4 ,the main spans are #hj feet1 and the pier spans #cb feet4 ,the width of the pier on the top is #aj feet #f inches 7for single line71 and the width at the bottom of the highest pier is #ajf feet #h inches4 ,in contrasting these light iron piers with what would have been required if constructed of masonry1 an idea may be formed of the enormous amount of material1 labour1 and time1 which would have been expended to erect the work in stone4 ,before the principle of lofty iron piers had been thoroughly developed1 many high piers had been built of timber both at home and abroad4 ,more particularly was this the case in the ,united ,states of ,america1 where the presence of magnificent timber close to hand offered special inducements for the use of wood4 ,like a mammoth scaffolding1 each pier was constructed with a most liberal supply of material1 judiciously selected and carefully put together1 but the danger of destruction by fire was ever present from the beginning4 ,probably more timber piers and bridges have been destroyed by fire than have been removed on account of natural decay4 ,one of the most notable of these timber-pier constructions was that of the ,old ,portage ,viaduct1 on the ,erie ,railway1 ,u4,s4,a4 ,fig4 #aja is a sketch of one or two of the piers4 ,this viaduct was more than #hjj feet long1 and #bcd feet high from the bed of the river to the rail-level4 ,the spans were #ej feet each4 ,masonry piers were carried up to about #be feet above the ordinary water-level of the river1 and upon these the timber superstructure was erected4 ,each timber pier consisted of three complete sets of framework1 securely connected together1 and also well stayed and braced to the adjoining piers4 ,this viaduct was destroyed by fire in #ahge1 and was reconstructed with piers and girders of iron4 ,railway bridges over or under public roads of primary or secondary importance must be constructed to the widths and heights prescribed for such works in the fixed regulations of the country in which they #ajc have to be built4 ,as a rule1 these road-bridges are simple and inexpensive in character1 except in towns1 or in cases where the line crosses the roads very obliquely1 or where the road is situated at the top of a deep cutting1 or bottom of a high embankment4 ,away from towns and out in the open country1 permission is generally obtained to divert the roads to a moderate extent1 so as to obtain a more favourable angle and height for the bridge2 but in towns1 where the roads become streets1 sometimes of great width1 with houses and shops on each side1 little or no diversion can be allowed4 ,a railway passing through a portion of a densely populated town must deal with the streets as they exist1 as any great alteration in their course or continuity would involve a large destruction of property4 ,with careful laying out it is possible to obtain favourable crossings for many of the streets1 but a number of others must be crossed obliquely1 and these oblique crossings very frequently result in a span twice the width1 or even more1 of what would be necessary to cross the street on the square4 ,bridge-work in towns is more costly than in the country1 as a higher class of work is demanded1 more finish or dressed work in the masonry or brickwork1 and more ornamentation in the screens and parapets in connection with the iron girder-work4 ,the work itself has to be carried on in a confined locality1 with limited space for materials and appliances1 and where the thoroughfare must be kept open4 ,where the height is sufficient1 and suitable materials readily obtained1 it is preferable to adopt an arch bridge1 as being of a much more permanent character than girders4 ,fig4 #ajb is an example of an ordinary over-line arch bridge to carry a public road over a double line of railway in a cutting of moderate depth4 ,fig4 #ajc shows a somewhat similar over-line arch bridge1 but its height from rail to road-level being greater1 side arches are introduced in preference to long heavy wing walls4 ,fig4 #ajd shows an over-line arch bridge in a rock cutting4 ,in this case1 by increasing the span and forming the springing bed in the solid rock1 the masonry of abutments and wing walls may be reduced to a minimum4 ,fig4 #aje is a sketch of an ordinary under-line arch bridge to carry a railway over a public road in an embankment of moderate height4 ,illustration3 ,fig4 #ajb1 #abh1 #abi1 #acj ,illustration3 ,fig4 #ajc ,illustration3 ,fig4 #ajd ,illustration3 ,fig4 #aje ,illustration3 ,fig4 #ajf ,illustration3 ,fig4 #ajg ,fig4 #ajf shows a similar under-line bridge1 but with curved instead of #aaj straight wing walls4 ,fig4 #ajg is an example of an under-line arch bridge in a rather high embankment1 and where side arches have been adopted instead of long wing walls4 ,the above six types are equally applicable for private roads crossing the railway1 but1 as previously mentioned1 a lesser width and headway will be accepted for under-line bridges for private or occupation roads1 than for public roads4 ,for the over-line bridges1 however1 the width and headway will be regulated by the number of lines and standard height of the railway4 ,when these arch bridges have to be built on the skew to suit an oblique crossing of the road1 extra care will be necessary in setting out the work1 and marking on the centering the spiral courses of the arching4 ,arch bridges may be built of masonwork or brickwork1 or a combination of the two4 ,if the available quarries do not yield good flat bedded stones readily worked1 it is better1 where possible1 to use strong hard bricks for the arching1 and utilize the stone for the remainder of the work4 ,although arching undoubtedly forms the most durable type of bridgework1 numbers of cases occur where the available height or space between rail-level and road-level is too small1 or the cost of masonry and brickwork too great1 to admit of anything but girder-work4 ,detailed sketches of some of the many forms of girder bridges are given in ,figs4 #acb to #aec1 illustrating various systems of roadways and parapets4 ,in some instances the main girders are made sufficiently deep to serve as parapets1 while in others a shallower girder has been adopted1 on top of which has been placed a light cast-iron parapet composed either of close plate-work or of ornamental open railings4 ,the open ironwork parapet has a good appearance1 but as a screen is not so efficient as the close cast-iron plates4 ,in addition to the bridges required for the regular public roads1 it is usually necessary to construct a certain number of occupation or private road bridges over and under the line to accommodate portions of estates and large properties intersected or severed by the railway1 and which would be inadequately provided for by ordinary gate crossings on the level4 ,the position and description of these occupation bridges is generally matter of private arrangement4 ,the bridges will be somewhat similar in character to the public road #aaa bridges1 but of much less width for the roadway4 ,those over the railway must have the standard span and height adopted as a minimum for the other over-line bridges1 and those under the railway must have the full width on the top for the lines of rails1 but will have less width between the abutments for the roadway4 ,foundations4--,so much depends upon the soundness and security of the foundations of any bridge1 viaduct1 or large building1 that it would be almost impossible to devote too much care to the selection and treatment4 ,unless the foundation be firm1 the entire structure will be exposed to the risk of failure1 either in subsidence of masonry1 giving way of arches1 or depression of girders4 ,a small matter overlooked during the construction of this part of the work will be most difficult to correct or adjust afterwards4 ,the insistent weight of all structures built of masonry or brickwork will cause the mass to settle to a certain extent1 according as the joints of mortar or cement become compressed by the number of superincumbent courses4 ,in a similar manner the gravel and clay of a foundation will compress more or less according to its compactness and the weight of the structure4 ,no inconvenience will1 however1 arise if the settlement or compression be uniform throughout the entire area4 ,in ordinary average1 dry1 solid ground1 a good foundation can usually be obtained at a moderate depth4 ,the removal of a few feet of the surface layers will generally lead to a good hard stratum of natural material sufficiently firm to carry the abutments and piers of railway bridges and viaducts4 ,two or more footings are usually adopted so as to distribute the weight over an increased area1 as shown in ,fig4 #ajh4 ,where the weight to be carried is considerable1 it is better to increase the number of the footings1 and give them a smaller projection1 as in ,fig4 #aji1 rather than have a lesser number and greater projection1 as in ,fig4 #ajh4 ,there is greater liability of fracture of the material in the latter than in the former4 ,care must be taken to distinguish between made ground and natural ground4 ,hollows which have been filled in must not be relied upon to sustain heavy weights2 the material may have been consolidating for years1 but it is safer to cut through it and found upon the natural stratum beneath4 ,illustration3 ,fig4 #aji1 #ajh1 #aaj1 #aaa1 #abd1 #aac1 #aad1 #aae1 #abe ,soils of a clayey nature must be dealt with very cautiously4 ,if the #aac ground be fairly level1 and the material firm1 a solid foundation may be obtained1 but the excavated portion should be covered up as quickly as possible to prevent any decomposing action taking place upon exposure to the open air4 ,the expansive nature of some clays must be carefully kept in view1 so as to guard against any disturbance in the finished foundation4 ,there are some descriptions of shale which when first opened out appear to have the solidity of hard rock1 and yet1 after a few days' exposure to the atmosphere1 are changed to the consistency of soft mud4 ,sand1 being composed of such small particles1 is almost incompressible1 and makes an excellent foundation so long as it can be retained in its position4 ,little or no settlement will take place if the sand remains undisturbed1 but so soon as it comes under the influence of running springs1 or underground drainage1 the fine particles of the sand will be gradually but surely carried away with the water1 and the entire foundation be undermined4 ,the opening out of a neighbouring excavation1 or the carrying out of some low-level drainage1 would endanger a construction which otherwise would be solid and permanent4 ,in many cases of soft ground1 more particularly abroad1 sand piles have been adopted and have given very good results4 ,the system is carried out by first driving a large wooden pile down through the soft material into the more solid stratum below4 ,the timber pile is then carefully withdrawn and the cavity filled with clean sand4 ,the number and distance apart of these sand piles will depend upon the nature of the ground and description and weight of structure to be carried4 ,clean1 compact gravel is one of the best materials to build upon1 being almost incompressible and quite unaffected by exposure to the atmosphere4 ,it is easily excavated and levelled off to the surface required4 ,a foundation of rock may be considered in the abstract as the most solid base to be obtained1 but it must be treated judiciously1 and a proper surface secured4 ,the outer portion of many descriptions of rock consists of blocks or layers of stone partially or entirely separated from the main bed1 and these1 lying in a loose condition1 are deceptive and treacherous as a foundation base4 ,the exposed rock should be carefully examined1 and all detached or outlying pieces or layers removed before placing any foundation course4 ,special care must be paid to all shelving rock1 and a level seating cut into it for the #aad entire width of the foundation1 as shown in ,fig4 #aaj4 ,a thick bed of concrete1 as in ,fig4 #aji1 makes an excellent foundation course4 ,when firmly set it becomes one solid massive base from end to end1 and prevents the yielding or dropping of masonry at any intermediate points4 ,there are many places in soft1 wet ground where instead of attempting to excavate all the soft material down to a harder stratum1 it is better to adopt timber pile foundations1 as shown in ,fig4 #aaa4 ,the size of the piles and their distance from centre to centre must be regulated by the description of material into which they have to be driven and the weight they have to sustain4 ,double waling pieces should be properly checked and bolted on to the heads of the piles1 and trimmed or levelled off to receive a double floor of thick planks4 ,the spaces round the heads of piles and walings should be filled in and levelled up to under side of flooring1 with cement concrete4 ,illustration3 ,fig4 #aab ,for bridges of moderate span1 over soft ground or over shallow fresh water1 strong cast-iron screw piles can be adopted with great advantage4 ,fig4 #aab shows a very usual form of screw pile1 made with an external screw at the lower end and with a sharp cutting edge to facilitate penetration into the ground4 ,the upper portions are made in suitable lengths1 and all to one pattern and template1 for convenience in carrying out the work4 ,the screwing into the ground is generally effected by means of a capstan or cross-head fixed to the top of the first working length of pile1 and which is pulled or turned round by ropes worked from stationary windlasses4 ,in some cases long bars or levers are attached in radiating positions to the capstan-head1 and a number of men are employed to walk round and round1 pushing the levers1 and in this way screwing the pile into the ground4 ,as the pile goes down the capstan-head has to be removed1 and additional lengths bolted on1 until the pile enters a solid stratum1 or is considered deep enough for the duty it has to perform4 ,the last or top length has generally to be cast to a special length to bring the work up to the exact height to receive the girders4 ,the core of excavated material passes up into the interior of the pile1 and in some cases becomes so compressed or tight as to require the use of an internal augur to remove a portion of it to enable the screwing to proceed4 ,the pile shown in ,fig4 #aab is one of a number which were successfully screwed into the ground to depths varying from #db to #dh feet4 ,a toothed or #aaf serrated edge1 as in ,fig4 #aac1 is sometimes given to the lower edge for screw piles which have to cut their way through a hard stratum4 ,all bolting flanges should be accurately turned and fitted to ensure close1 parallel surfaces when bolted together4 ,the joint shown at ,a1 ,fig4 #aab1 is one the writer has used to a large extent for the bolting flanges of cast-iron screw piles and cylinders4 ,it is very simple in form1 readily coated with white lead to ensure a water-tight joint1 and as the upper length is practically recessed1 or let into the lower length1 the exact continuity of the different castings is secured4 ,solid screw piles of wrought-iron or steel1 similar to ,fig4 #aad1 are used for some descriptions of work4 ,these are generally made in long lengths1 in sizes varying from #d to #h inches in diameter1 and with screw blades of wrought-iron or cast-iron fixed in the most secure manner to resist the strain produced when screwing into the ground4 ,the couplings for these solid piles must be very carefully made1 all contact surfaces truly faced and fitted1 bolts turned1 and bolt-holes drilled4 ,fig4 #aae is a sketch of a hollow cylindrical water-jet pile1 which has been used successfully in cases of light sand4 ,the lower end of the pile is made externally in the form of a solid disc1 terminating in a conical point1 having an aperture in the centre to correspond to the water-jet4 ,to the top of the pile is secured a tight-fitting cover through which a tube passes from a force pump4 ,water at high pressure is pumped into the tube1 and as it forces its way out through the conical point the sand is stirred up and loosened1 and thus allows the pile to descend4 ,when the pile has been lowered to a sufficient depth the pumps and tube are removed1 and the sand settles down into its former compact condition4 ,great care must be used with the first two or three lengths of any screw pile to ensure the pile taking a correct or true vertical position4 ,each series of screw piles should be properly braced together to obtain stability under moving loads4 ,illustration3 ,fig4 #aaf ,illustration3 ,fig4 #aag ,hollow cylinders of cast-iron1 wrought-iron1 or steel form most efficient foundations or piers for large bridges over soft ground or fresh water of considerable depth4 ,made open at the bottom1 and constructed of complete rings1 or1 if of large diameter1 of rings built up in segments and securely attached together with water-tight #aai joints1 the cylinder is placed in its proper position on the ground or lowered into the water preparatory to sinking4 ,the lower length is made with a sharp cutting edge to facilitate penetration4 ,by excavating and removing the material round the cutting edge and base inside the lower length1 the cylinder descends gradually either from its own weight or by assisted weights1 and length after length is added until it is sunk to the depth required4 ,the excavated material is filled into buckets and hoisted to the surface by a winch fixed on the top length4 ,when sinking in water the working top of the cylinder is always kept at a suitable height above the water for convenience in removal of the earth or clay from the interior to barges or gangways alongside4 ,some strata are more favourable for cylinder sinking than others4 ,material of a strong clayey nature admits but a small amount of water into the excavation1 and a moderate-sized pump will keep the working fairly dry until considerable depth has been reached4 ,some other materials are so open that the water cannot be kept down with ordinary pumps1 and the cylinders can then only be lowered by the pneumatic process4 ,this process has been carried out in two methods1 one of them on the vacuum principle1 and the other by air pressure1 or1 as it is termed1 the plenum system4 ,with the former method the cylinder is placed in position1 and an air-tight cap1 through which a pipe passes1 is secured on the top4 ,powerful air-pumps are then set to work1 and the partial vacuum thus created in the interior causes the material round the cutting edge and base to be loosened and drawn into the cylinder1 the cylinder at the same time going down or sinking by its own weight1 or assisted1 if necessary1 by added weights4 ,the cap is then taken off1 and the material removed from the interior1 the operation of exhausting and emptying the interior being repeated until the cylinder is sunk to its proper depth4 ,this method has been found to work well in strata which contained a large proportion of clay to assist in excluding the air and water1 but was not nearly so successful when applied to material containing stones and large boulders4 ,the plenum process is based on the principle of the diving-bell1 the water being prevented from entering at the bottom by keeping the cylinder full of compressed air4 ,an air-chamber1 or air-lock1 with perfectly air-tight joints1 is securely fixed to the top or upper #abj working length of the cylinder1 and no access can be obtained to the interior of the cylinder without passing through this air-lock1 which has one lower door or valve opening into the cylinder1 and an upper door opening out into the open air4 ,temporary inside staging is formed by putting planks across from flange to flange1 and placing short ladders on these landings for the use of workmen descending or ascending4 ,the excavated material is hoisted by a winch1 generally placed on the landing just under the air-lock4 ,the air-pump is placed in some convenient position outside1 near at hand1 the pressure-pipe passing through the air-lock into the interior of the cylinder4 ,air is forced into the cylinder to a pressure sufficient to drive out and keep out the water from the interior1 and allow the workmen free access for excavating the material round the cutting edge and base of cylinder4 ,the amount of pressure required will depend upon the depth of the working below the level of the water alongside4 ,men accustomed to the process can work without much inconvenience under a pressure of #bj to #bb pounds per square inch1 equal to a depth of #de to #ej feet2 but when the pressure exceeds #be pounds1 the duty becomes very trying1 and is attended with considerable risk4 ,instances are recorded of men working at depths of #aje and #aaj feet1 necessitating a pressure of over #de pounds per square inch2 but it is very questionable whether the men exposed to such a severe ordeal were not permanently affected1 if some of them did not actually succumb4 ,it will sometimes occur that1 after sinking through soft porous strata to a considerable depth1 a layer of clayey material is penetrated sufficiently retentive to keep out the water and permit of the removal of the air-lock and the completion of the sinking as an open-top cylinder4 ,when working on the plenum system everything must pass through the air-lock1 both materials and men4 ,the excavated material is hoisted up to the level of the air-lock1 the upper and lower doors of which must be closed1 and the pressure inside the air-lock brought to the same as that inside the cylinder by means of a regulating valve4 ,the lower door is then opened to admit the excavated material1 and then closed again to cut off all communication with the interior of the cylinder4 ,the upper door is then opened1 and the material hoisted out into the open air4 ,the same process has to be adopted for the egress of the workmen1 and the reverse arrangement for the ingress of men and #aba materials4 ,the shape and dimensions of the air-lock may be varied according to circumstances1 but the principle will remain the same4 ,when the cylinder has been lowered to what is considered a sufficient depth1 it is usually loaded with a certain amount of dead weight in the shape of old iron or other convenient material1 and allowed to remain loaded for some days to ascertain if it will sink any further4 ,should this test be found satisfactory1 the dead weight is removed1 and the interior of the cylinder pumped dry and carefully filled with good cement concrete4 ,cylinders for foundations are generally made circular in section1 that form being the most convenient for turning and facing the flange-joints4 ,they can1 however1 be made oval in section1 or of any section that may be found most suitable for the work required4 ,figs4 #aaf and #aag give the particulars of a double-line railway bridge carried on cylinder piers across a river4 ,the detail sketches explain the form of cutting edge1 flange joint1 and method of bracing4 ,this bridge is one that was reconstructed and widened from a single-line to a double-line bridge4 ,traffic was carried over on one line while the second line was being erected1 hence the reason why one strong central girder was not adopted4 ,cylinders of #g feet diameter and upwards are sometimes filled with concrete in the lower portion1 on which is built either a circular lining or a solid mass of masonry or brickwork up to the level of the girder-blocks4 ,in some cases the cylinders proper1 together with their concrete filling1 terminate a little above the water-level1 and upon these foundations are erected strong cast-iron columns1 plain or ornamented in design1 to carry the girders and roadway4 ,the cylinder itself is generally considered merely as a casing or medium for obtaining a foundation1 the weight of the superstructure being carried on the internal filling or lining4 ,caissons constructed of plates of wrought-iron or steel are much used for the foundations of large piers in deep water4 ,practically they may be considered as cylinders on a large scale1 with the difference that whereas cylinders are generally continued up to the under side of the girders of the superstructure1 caissons are only carried up to a short distance above the water-level4 ,a caisson forms a strong water-tight iron cofferdam1 from which the water can be excluded1 and a masonry or #abb brickwork pier constructed inside4 ,it may be made all in one piece to correspond to the form of the pier1 or in separate pieces to form one whole1 each being sunk independent of the other1 and connected together afterwards4 ,being built up of plates cut to the proper size and shape1 it is a very simple matter to rivet on additional tiers of plates as the caisson is lowered deeper and deeper into the bed of the river4 ,the lower length is made with a cutting edge to penetrate the ground2 the exterior is made without any projection larger than the rivet heads1 and the interior is strengthened with ,t-irons or double ,l-irons at the joints1 and strong cross-bracing to resist the pressure of the water4 ,about #g or #h feet above the cutting edge a strongly framed iron floor is riveted to the vertical sides1 and strengthened by plate-iron under-brackets placed at short distances4 ,the excavators work in the space below the floor1 and the excavated material is passed up through openings formed in the floor at convenient points to suit the working4 ,the methods of lowering a caisson are the same as for lowering a cylinder4 ,if the pneumatic system has to be adopted1 then two or more air-tight tubes of liberal dimensions 7say #e to #h feet diameter71 according to the size of the caisson1 must be attached to the floor1 and on the top of each of these tubes air-locks must be secured for the removal of men and materials4 ,the masonry or brickwork of the pier is built upon the iron floor1 and a portion of this building work is usually carried on during the sinking of the caisson to obtain weight to assist in the lowering4 ,when down to the proper depth1 the space below the floor is properly cleared of dbris and water1 and then carefully filled in with cement concrete4 ,some caissons are made with vertical sides throughout their entire height2 others have an outward taper for #ae or #bj feet on the lower end4 ,the former are not only simpler in construction1 but are more easily kept in a vertical position during the sinking4 ,caissons are usually put together in some convenient place near the edge of the water1 and then conveyed on pontoons to the sites of the piers4 ,great care is required in lowering them into position in the bed of the river1 and guide-piles1 guy-chains1 and other appliances are frequently necessary to keep them vertical during the sinking4 ,the form1 dimensions1 thickness of plates1 cross-bracing1 and general arrangement will depend upon the size and depth of the pier to be #abc constructed4 ,caissons for heavy work on difficult or treacherous ground require great care1 not only in their construction1 but also in placing them in exact position1 and in sinking them correctly to their proper depth4 ,a tilted caisson is a most difficult subject to handle1 and entails heavy expenditure to restore it to a true vertical position4 ,by making careful borings1 the engineer can ascertain very closely the depth to which the caisson will have to be lowered to obtain a good firm foundation4 ,with this information the caisson can be so constructed that the upper portion1 termed the temporary caisson1 commencing a few feet above the bed of the river1 can be detached1 and removed at the completion of the work from the lower or permanent portion sunk below the ground line4 ,fig4 #aah gives sketches of a wrought-iron plate-caisson applied to a deep-water river pier1 and lowered to its full depth by the pneumatic process2 dotted lines show the air-tubes through which the excavated material is hoisted and emptied into barges alongside4 ,many large and important pier foundations have been constructed on the system of brick cylinders or wells1 particularly in ,india1 where the foundations for large river viaducts have to be carried down to great depths through thick deposits of soft material4 ,these wells are built upon ,v-shaped curbs to facilitate the penetration when sinking4 ,fig4 #aai is a section of a well with a wrought-iron curb1 and ,fig4 #abj is a similar well with a wooden curb4 ,the wrought-iron curb is made in segments for convenience of transport1 the pieces forming the complete ring being bolted or riveted together at the site of the foundations4 ,the wooden curb is composed of several thick layers of hard wood planking cut to the proper shape1 and laid with broken joints1 the whole being bound together with suitable bolts and spikes4 ,in some cases the lower or cutting edge of the wooden curb is strengthened or protected by a sheathing of wrought-iron plates4 ,illustration3 ,fig4 #aah ,illustration3 ,fig4 #aai1 #abj1 #aba1 #abb1 #abc ,well foundations are usually put in when the rivers are at their lowest1 and reduced to a few small channels in the great width of dried-up river bed4 ,this condition enables the greater portion of the curbs to be conveniently and accurately placed in position on dry ground1 or on ground which1 although soft and muddy1 is not covered with water4 ,should the site of one of the wells occur in one of the small channels1 the stream can be diverted to one side1 and a small #abf artificial island made to receive the curb above water-level4 ,when a curb is fairly fixed in position1 the work of building the brick well can be commenced4 ,with the wrought-iron curb the triangular cavity between the vertical plate and sloping plate must be filled with concrete to form a level base for the first course of brickwork4 ,the wooden curb being composed of horizontal layers of timber1 is ready to receive the brickwork without further preparation4 ,to strengthen and keep the brickwork firmly tied together1 strong wrought-iron vertical tie-rods1 #a or #a inch in diameter1 are generally built into the work--as shown in the sketches--at distances about four feet apart4 ,the lower end of the bottom tier of tie-rods is secured to the curb1 and the upper end passed through a strong wrought-iron plate-ring1 which is continuous all round the brickwork4 ,a long deep nut is screwed down over the top or screwed end of tie-rod until the plate-ring is down tight on the brickwork4 ,the tightening nuts are made sufficiently deep to receive the lower ends of a second series of vertical tie-rods1 which in like manner pass through another wrought-iron plate-ring on the next section of brick well1 and the same arrangement is continued for the full height of the well4 ,the lengths of the tie-rods will depend upon the lengths of the section of brickwork to be built at a time1 and may vary from #aj to #ae feet4 ,as the work of building proceeds the curb and brick well will sink gradually into the ground1 and down to a certain depth1 varying according to the material of the river bed1 the weight of the brick well itself will effect the penetration and lowering4 ,beyond this depth the lowering must be done by scooping or dredging the material from the inside of the well1 and placing heavy weights of old railway iron or other convenient masses on the top4 ,when one section or length of well has been sunk down1 then another set of tie-rods are inserted into the deep nuts1 and another section of brickwork commenced4 ,the operation of lowering is rather tedious1 as all the weights have to be hoisted up on to the top of the length in hand1 and piled so as to leave space for lifting out the material dredged from the interior2 and then1 when the length has been lowered1 all the weights must be removed before the brickwork can be resumed on another length4 ,where the river bed consists of soft material1 the excavation inside the well can generally be effected by suitable dredges or scoops worked #abg from the surface or top of brickwork4 ,should trees or other obstructive masses be met with embedded in the strata1 it will be necessary to employ divers to remove them piecemeal out of the way of the curb4 ,when the brick well has been lowered down to the full depth1 and is thoroughly bedded in a stratum of strong material1 the test weights should be left on for some time to ascertain if there is any further sinking4 ,after all the weights have been removed the bottom of the well can be dredged out clean1 and the interior filled in with concrete to such height as may be considered necessary4 ,brick wells must be watched carefully to ensure that they sink down in a perfectly vertical position4 ,any inclination away from the perpendicular must be corrected at once by means of guys and struts1 the same as in sinking iron cylinders4 ,the principal difficulty will be with the first #bj or #be feet4 ,the diameter of the well will depend upon the weight it has to carry1 and its height from river bed to under side of girders4 ,the wells may be either circular or polygonal in section1 and built singly or in pairs1 as shown in sketches 7,fig4 #aba74 ,many piers and abutments of bridges in shallow or moderately deep water are built by means of coffer-dams of timber and clay puddle4 ,the coffer-dam forms a water-tight wall round the site of the foundation1 from which the water is pumped out1 and the excavation carried down to the depth required4 ,in very shallow water it is sometimes sufficient to drive only a single row of piles1 and form a bank of good clay puddle on the outside1 as shown in ,fig4 #abb4 ,in deep water it is necessary to drive a double row of piles1 #c or #d or more feet apart1 and fill in the space between with clay puddle1 as shown in ,fig4 #abc4 ,the piles for coffer-dam work should be carefully selected1 of good timber straight1 and correctly sawn on the contact faces4 ,guide-piles are first driven in proper line and position round the intended foundation4 ,to these strong horizontal double waling pieces are securely bolted1 one on each side of the guide-pile1 one pair near the top1 and the other pair as low down as can be placed4 ,the sheeting piles1 which are lowered down between the horizontal waling or guiding pieces1 are driven as close to one another as possible1 being assisted in doing so by the sheet-pile shoe1 shown on ,fig4 #abd1 which is made not with a point like an ordinary pile shoe 7,fig4 #abe71 but with a #abh cutting edge slightly inclined1 so that in driving the tendency of the pile is to drift towards the pile previously driven4 ,sometimes the outer row of piles consists of whole balks1 and the inner row of half balks2 the size of the piles must1 however1 be regulated by the depth and current of the water4 ,when both rows of piles have been completed1 the space between should be dredged out1 and then filled with carefully prepared clay puddle4 ,to enable the puddle to adapt itself thoroughly to the wooden sides1 it is desirable to remove the inside walings after all the piles are driven1 as any internal projections interfere with the proper punning and settling of the puddle4 ,the swelling of the puddled clay has a tendency to force apart the two rows of piles1 and to counteract this as much as possible1 iron tie-rods should be passed through from side to side every few feet1 and screwed up against large washers placed on the outside of the outer walings4 ,strong struts or cross-bracing of timber must be placed from side to side inside the coffer-dam to resist the pressure of the water in the river4 ,this cross-bracing can be removed gradually as the work of building progresses upwards1 and be replaced with short struts wedged in against the sides of the finished courses4 ,in cases where the ground is soft1 and when it is not considered prudent to excavate the foundations deeper for fear of disturbing the stability of the coffer-dam piles1 rows of large1 square bearing-piles may be driven in the floor of the foundation1 as shown in ,fig4 #aaa4 ,the tops of these bearing-piles must all be sawn off to the same level1 and a platform of strong double planking securely fixed to the piles to receive the foundation course of concrete1 masonry1 or brickwork4 ,the spaces around the tops of the piles and the under side of the timber platform should be filled in with good cement concrete4 ,the interior of the coffer-dam is kept dry by constant pumping1 either by hand pumps or steam pumps1 according to the volume of water finding its way into the foundations4 ,when the finished pier or abutment has been carried up above the river water-level1 the coffer-dam is no longer required1 and may be removed4 ,sometimes1 to save the timber1 the piles are drawn by means of strong tackle fitted up for the purpose2 but in doing this there is considerable risk of disturbance to the foundations1 and it is better to leave the piles in the ground and employ divers to cut off the tops a little above the bed of the #abi river4 ,in preparing the design for a large foundation it is absolutely necessary to first ascertain by careful borings the description of material upon which that foundation must be placed1 so as to proportion the area of bearing surface to the weight to be sustained4 ,some materials will naturally carry more weight than others1 and although the engineer cannot always select the material he would prefer1 he can1 however1 control the superficial area of the foundations4 ,much valuable information has been obtained both from experiments and from comparisons of actual practice1 and the following memoranda may be useful for reference1 as indicating the pressures per superficial foot which may be safely put on various materials3-- ,moderately stiff clay #b tons4 ,chalk #d 0 ,solid blue clay #e 0 ,compact gravel and close sand #f 0 ,solid rock #ab 0 ,doubtless the above weights have been exceeded in many cases1 but it is better to be on the safe side1 and leave a good margin for stability4 ,large subaqueous foundations for heavy piers and abutments are costly and tedious1 and especially so when the pneumatic process has to be adopted4 ,special appliances and well-trained1 experienced workmen are requisite1 and if all the men and materials have to pass through the air-locks1 the progress of the work must necessarily be slow4 ,when the foundations have been completed up to the level of the water1 the construction can be pushed on more rapidly1 as the work of scaffolding1 hoisting1 and building1 can all be carried on in the open air4 ,amongst the very many types of arch-work and girder-work adopted for railway purposes1 the following examples from actual practice may be useful for reference3-- ,illustration3 ,fig4 #abf1 #abg ,fig4 #abf represents small #bd-;foot span1 low viaduct arching suitable for a line passing through towns or villages1 where ground is valuable and the area to be covered must be kept as small as possible4 ,the arches may be utilized for stables1 stores1 or roads of communication between the lands and properties intersected by the railway4 ,the segmental form gives a better headway underneath than the semicircular1 besides containing less material in the arching proper1 and requiring a smaller amount of centering4 ,every precaution should #aca be taken to prevent water percolating through any portion of the arching1 or haunching1 and a thick layer of good asphalte should be placed over the entire upper surface1 and carried well up the lower portion of the parapet walls1 as shown on the sketch4 ,the cast-iron pipes with rose heads form a very efficient means of taking away the rain-water which filters through the ballast and filling4 ,the pipes should be carried down in chases1 or recesses1 built in the fronts of the piers1 to protect them as much as possible from injury in the yards below4 ,rose heads1 pierced with holes1 and surrounded with small stones hand-laid1 serve well to conduct the water into the pipes4 ,where the arching is of considerable length1 recesses or refuges for the platelayers may be obtained by substituting a short length of cast-iron-plate parapet1 instead of the stone or brick parapet1 over some of the piers1 as indicated in the sketch4 ,fig4 #abg shows a similar description of arching for spans of #cj feet4 ,the above two examples represent plain substantial work1 but if circumstances warrant more external finish1 this can readily be added without interfering with the general arrangement4 ,in a similar manner1 if considered preferable1 the arches may be made semicircular or elliptical4 ,in the sketches shown of the arched over-line and under-line bridges1 the arching and coping of parapets are in brick1 and the remainder of the work in stone4 ,in very many cases brick will be found cheaper and more expeditious for arching than stone1 unless the quarries turn out stone in blocks which can be conveniently trimmed for arching4 ,all bricks used for arch-work should be hard and well burnt1 and special care should be taken in the selection of those to form the under-side course1 which will be exposed to the atmosphere4 ,for moderate spans arches have been successfully constructed of concrete4 ,for this description of work the materials should be carefully gauged and mixed together1 and the finished work should be allowed to stand some time on the centres to allow the concrete to become thoroughly set4 ,illustration3 ,fig4 #aca ,in ,fig4 #ajb1 the cutting being deep1 almost up to the level of the public road1 the foundations of the wing walls are built in steps1 resulting in a minimum of masonry below the finished ground line4 ,where the cutting is shallow1 and the public road has to be brought up to the bridge on an embanked approach1 the greater portion of the wing #acc walls will have to be built up from the solid or original ground1 and there will be a large amount of masonry below the finished ground line1 as indicated in ,fig4 #abh4 ,in some cases of over-line bridges it is necessary to curve the wing walls to correspond to the road which turns off to the right or left after crossing the railway1 as shown in ,fig4 #abi2 or the wing walls may have to form two separate curves where the road branches off in two directions after leaving the bridge1 as shown in ,fig4 #acj4 ,fig4 #aca shows plan1 elevation1 and cross-section of an under-line arch bridge1 considerably on the skew1 carrying a railway over a river4 ,the wing walls are curved1 and very similar in type to some of those in preceding examples4 ,the river bed and ground alongside being of solid rock1 good foundations were obtained at a very moderate cost4 ,on many railways constructed in the beginning as single lines only1 the over-line bridges have been built for double line4 ,the additional cost in the outset has been small1 compared with the great expenditure which would be incurred afterwards in reconstructing the bridges to suit a double line4 ,the general arrangement of abutments and wing walls shown in the foregoing examples will apply to similar classes of bridges where girder-work is adopted instead of arching4 ,there are many ways of forming the floor or deck of a girder bridge intended to carry a railway over a road or stream4 ,in some cases it will be imperative to have a thoroughly water-tight floor to prevent rain-water percolating through to the roadway below2 while in others1 such as bridges over streams1 and secondary roads1 this special provision will not be necessary1 and a lighter and more economical floorway can be adopted4 ,a strong wrought-iron or steel-plate flooring1 with its corresponding filling and ballasting1 means not only so much additional cost in the flooring proper1 but also so much additional dead weight to be carried by the main girders4 ,illustration3 ,fig4 #acb1 #acc1 #acd1 #ace1 #acf1 #ada ,fig4 #acb is a sketch of rolled joist-iron ,i-girders and timber floor frequently adopted for small farm roads and cattle creeps of #aj or #ab feet span4 ,a beam of timber is fitted in between the two rolled joist-irons1 and the three pieces securely fastened together with strong iron bolts placed about #c feet apart4 ,these small compound girders rest on bearing-plates of wrought or cast iron1 and are held #ace together and to gauge by tie-rods1 as shown4 ,the rails are spiked or bolted down on to the timber beams1 and the flooring formed of strong planking4 ,fig4 #acc shows an arrangement of plate girders for a #af-;foot opening over a stream4 ,the girders are placed immediately under the rails1 and are tied together by plate-iron cross-bracing the same depth as the main girders4 ,the flooring consists of #d-;inch planking laid with -inch spaces1 on which are laid longitudinal rail-bearers #ad inches wide by #g inches thick4 ,fig4 #acd is a sketch of a somewhat similar arrangement for a lattice-girder bridge1 #de feet span1 carrying a single line of railway over a river4 ,the main girders are tied together by lattice-work cross-bracing4 ,the floorway consists of #e-;inch planking1 laid with -inch spaces1 on which is placed the #ad feet by #g feet longitudinal rail-bearers4 ,plate-iron outside brackets are riveted to the main girders to carry the ends of the planking and light tube-iron parapet4 ,fig4 #ace illustrates an example of trough girders1 constructed to carry a double-line railway over a country road #be feet wide1 where the space from under side of girder to rail-level is small4 ,the girders are constructed in pairs1 with short1 shallow cross-girders at #c feet #f inch centres1 riveted in between them to carry longitudinal timbers on which the rails are laid4 ,bottom plates1 #e_/h inch thick1 unite the two girders for the length of their bearing on the abutments1 and a similar plate1 #i inches wide1 unites them at the centre2 the remainder of the span is left open to prevent the lodgment of rain-water4 ,three strong tie-rods are placed to keep the girders to gauge4 ,curved wrought-iron ballast-plates are used between the running-rails1 and plank flooring forms the rest of the covering4 ,illustration3 ,fig4 #acg ,fig4 #acf is a sketch of a plate-girder bridge over a country road #bh feet wide1 with the load carried on the lower flange of girder4 ,three main girders carry the double line of railway1 the centre one having double the strength of each of the outside girders4 ,on the top of the cross-girders1 strong angle irons are riveted to serve as guides and supports for the longitudinal timbers which carry the rails4 ,every third cross-girder has raised ends to give increased lateral stability to the main girders4 ,a close cast-iron plate parapet forms a screen to the roadway4 ,wrought-iron ballast-plates are used between the running-rails1 and the remainder of the flooring is of timber4 ,fig4 #acg gives the particulars of one #fj-;foot span of a viaduct #acg carrying a double line of railway over tidal water4 ,the main girders are placed one under each line of rails1 and all the four are strongly tied together by lattice-work bracing the full depth of the girders4 ,the outside footpaths for the platelayers are carried on strong brackets1 riveted to the main girders4 ,longitudinal timbers1 coped with angle iron1 are placed as outside guards1 alongside each rail1 for the full length of the viaduct4 ,wrought-iron ballast-plates are placed between the running-rails4 ,the remainder of the footways consist of timber planking1 laid with half-inch spaces1 and covered with a layer of small pebbles as a protection against fire4 ,fig4 #ach shows a very similar arrangement in a viaduct carrying a single line of railway across a river4 ,the two main lattice girders--#ff feet span--are placed at #i-;foot centres1 to obtain greater stability4 ,the cross-girders are extended to carry the outside footpaths and handrailing4 ,outside guards are placed alongside each rail as in the preceding example4 ,wrought-iron ballast-plates are fixed all along between the running-rails1 and timber planking used for the rest of the floorway4 ,fig4 #aci gives cross-section of a lattice-girder bridge1 #hb feet span1 carrying a single line of railway over a river1 with the load carried on the lower flange4 ,the cross-girders are placed at #d feet #c inch centres4 ,wrought-iron ballast-plates compose the floorway between the rails1 and timber planking covers the rest of the bridge4 ,plate diaphragms1 or stiffeners1 of the form shown at ,a1 ,a1 ,a1 ,a1 are riveted to the main girders at five places in their length4 ,fig4 #adj shows cross-section of a lattice-girder bridge of #bjj feet span1 carrying a single line of railway over a river1 the load being placed on the lower flange4 ,the floorway consists of plate-iron cross-girders1 spaced at #d-;foot centres1 on which are placed the longitudinal rail-bearers and planking1 the latter being covered with a layer of clean pebbles for the width between the running-rails4 ,as the depth of the main girders was sufficient to admit of overhead bracing1 strong plate-iron diaphragms1 of the form shown on the sketch1 were riveted to the main girders at every #ej feet4 ,these diaphragms thoroughly brace the two girders together1 and effectually prevent any tendency to side-canting1 at the same time imparting an effective appearance to the bridge4 ,illustration3 ,fig4 #ach1 #aci1 #adc ,fig4 #ada shows cross-section of a plate-girder bridge1 of #cf feet #aci span1 carrying six lines of way across a street4 ,strong plated cross-girder bracing1 at #d feet #h inch centres1 is riveted to the main girders1 and the top is covered with old ,barlow rails1 #ab inches wide1 and weighing #ij lbs4 per lineal yard4 ,a layer of asphalte1 about #a inches thick1 is carefully laid all over the upper surface of these rails to make a thoroughly water-tight floor4 ,clean gravel is placed on the top1 on which are laid the sleepers and rails of the permanent way4 ,rain-water passes through the gravel into the hollows of the ,barlow rails1 and finds its way into suitable drains provided at each abutment4 ,this arrangement not only prevents the falling of drip-water into the street below1 but permits of the alterations of the lines of way1 or putting in of cross-over roads on the surface above4 ,the outside main girders are made deeper1 and are surmounted by close cast-iron parapets4 ,fig4 #adb gives the particulars of a three-span plate-girder bridge1 constructed to carry a double line of railway over two other railways and a canal1 the load being placed on the lower flange4 ,two main girders are used for each line of way4 ,strong plated cross-girders are placed at #e feet #c inch centres1 and on the top of these is laid a flooring of old ,barlow rails1 terminating at the sides with sloping wing-plates riveted to the cross-girders and main girders1 the entire surface being covered with an inch and a half layer of asphalte4 ,good gravel ballast is placed on the top1 on which are laid the sleepers and rails4 ,one central main girder of sufficient strength would have been as efficient as the two central girders1 but there was a practical difficulty which prevented its adoption4 ,the new girder-work was built to replace an old structure of peculiar arrangement1 and to keep the traffic going on one line there was no alternative but to make each line of way complete in itself4 ,illustration3 ,fig4 #adj1 #add ,fig4 #adc illustrates an example of jack arches in concrete built between strong plate-girders4 ,the span of the girders was only #af feet1 but the opening or roadway was of considerable length1 and passed under a portion of a busy station yard4 ,the girders are placed at #f-;foot centres1 and tied together in pairs by #a-;inch tie-rods1 three to the span1 spaces of #f inches in plan being allowed between each set of the rods4 ,the concrete was curved up to the top plate of the girder1 as shown1 and the entire surface covered with a thick layer of asphalte1 on which were placed the ballast and permanent way4 #ada ,brickwork might have been used for the jack-arching1 but concrete was considered more convenient4 ,fig4 #add shows the cross-section of a truss-girder bridge of #abc feet span1 carrying a double line of railway over a wide thoroughfare1 the load being placed on the lower flange4 ,there are two main girders1 each #ab feet #f inches deep in the centre1 and #h feet deep at the ends4 ,plate cross-girders are placed at #d feet #f inch centres1 on which is riveted longitudinal plate-iron troughing1 extending across the bridge and terminating at the sides with wing-plates1 as shown4 ,the entire floor is covered with a thick layer of asphalte previous to filling in with ballast to receive the permanent way4 ,plate stiffeners are adopted in this bridge very similar to those in ,fig4 #aci4 ,fig4 #ade gives plan1 elevation1 and cross-section of a plate-girder bridge of #ie feet span1 carrying a double line of railway over a very busy street4 ,there are two curved-top main girders1 each #aj feet #i inches deep in the centre1 and #f feet #g inches deep at the ends4 ,the arrangement of cross-girders1 longitudinal plate-iron troughing1 and permanent way1 is very similar to that in the preceding example1 but the side wing-plates are carried up higher1 and are riveted up to the web-plate of main girder1 forming continuous stiffeners from end to end of the main girders4 ,a light1 ornamental1 close cast-iron parapet is bolted on to the top of the curved1 or upper1 boom of the main girder1 the top line of the parapet being carried out parallel to the bottom boom of girder4 ,this bridge crosses the street very obliquely1 and1 although cast-iron columns were allowed at the edge of the footpaths1 the main spans are unavoidably large4 ,when designing the above bridge1 the writer had to adopt a girder that would form a screen1 to provide a deck1 or floor-way1 which would be not only water-tight1 but also deaden as much as possible the sound or vibration of passing trains1 and at the same time give some ornamental appearance to the girders and parapets4 ,this bridge carries a constant service of heavy trains2 it is perfectly dry underneath1 and is remarkably free from noise or vibration4 ,illustration3 ,fig4 #adb ,fig4 #adf shows cross-section of a plate-girder bridge of #dj feet span1 carrying a double-line railway over a street1 in a situation where the depth from top of rails to under side of girders had to be made as small as possible4 ,three main girders were used1 the centre one being #adc double the strength of each of the outside girders4 ,instead of ordinary cross-girders1 transverse plate-iron troughing was adopted1 very similar in section to the longitudinal iron troughing in ,fig4 #ade1 but stronger4 ,the troughing rested on the angle iron of bottom flange of main girder1 and was riveted to the vertical web-plates of main girders1 shallow additional vertical plates being inserted alongside web-plates to prevent any drip-water or moisture coming in contact with the main web-plates4 ,the entire surface of the troughing was well covered with asphalte before filling the hollows with gravel ballast4 ,an ordinary transverse wooden sleeper was placed in each hollow1 and on these sleepers the rails were secured as shown4 ,in this case--as in others of transverse troughing--the rain-water had to be conveyed away from the hollow of each trough by a separate outlet into longitudinal gutters shown at ,a1 ,b1 and continued on to the abutments4 ,transverse troughing is always more troublesome than longitudinal troughing1 as both ends of each trough must be effectually closed to prevent the drainage water leaking out on to the web-plates1 or angles of the main girders4 ,with longitudinal troughing the water is readily carried away from each hollow1 to cross drains constructed at the piers1 or abutments4 ,fig4 #adg shows cross-section of a truss-girder bridge1 #abj feet span1 carrying a single line of railway over a river4 ,the cross-girders are placed at #aj-;foot centres to correspond to the vertical members of the main truss-girder4 ,longitudinal plate-iron rail-girders are riveted in between the cross-girders1 and the entire floor is covered with curved wrought-iron ballast plates1 as shown4 ,the rails are carried on longitudinal timbers1 which are bolted on to the rail-girders4 ,angle iron brackets1 riveted on the top of the cross-girders1 keep the rail timbers in position and gauge4 ,illustration3 ,fig4 #ade ,in each of the above examples1 where longitudinal rail timbers are adopted1 flange rails are shown1 as many engineers prefer to have a continuous bearing for the rails on bridges1 in case of rail fracture4 ,there is nothing1 however1 to prevent the chair road being laid on longitudinal timbers1 and for this purpose the writer has used chairs of the ordinary pattern1 specially cast with side lugs to grip the timber1 as shown in ,fig4 #adh4 ,chairs of this form have a very firm #ade hold on the longitudinal timber1 and the side lugs check any tendency of the splitting or opening of the wood when putting in the spikes or screw bolts4 ,fig4 #adi shows cross-section of a plate-girder over-line bridge1 #cb feet span1 carrying a private road1 #ab feet wide1 over a double-line railway4 ,the road traffic being small1 the floorway was constructed of creosoted planking carried on rolled ,i-iron cross-girders placed at #c feet #h inch centres1 and riveted to the main girders4 ,the horse-tread track was provided with a second layer of planking1 laid transversely1 to take up the wear1 cross battens1 #d inches by #b inches1 being placed at #ab-;inch centres1 and sand spread between to give good foothold4 ,a light lattice-work parapet was bolted on to the top of the main girders4 ,fig4 #aej gives cross-section of a plate-girder over-line bridge1 #cj feet span1 carrying a private road1 #bj feet wide1 over a double-line railway4 ,the main girders are tied together by lattice-work bracing1 spaced at #g-;foot centres4 ,curved wrought-iron plates are laid across from girder to girder1 and butt against a narrow horizontal plate1 which forms part of the upper boom4 ,the curved plates are riveted on to the top of girder1 and form a continuous iron floor1 or deck1 from side to side of the bridge4 ,upon this iron floor is laid an ordinary asphalte roadway4 ,the outside girders are made deeper1 and carry an ornamental cast-iron parapet4 ,in some bridges of a similar construction1 the roadway is formed of creosoted wooden block paving1 on a foundation of asphalte4 ,illustration3 ,,bridge ,,carrying ,,the ,d4 ,w4 ,,and ,w4 ,,railway 7,,loop ,,line7 ,,over ,,amiens ,,street1 ,,dublin4 ,to face p4 #add4 ,illustration3 ,fig4 #adf1 #adg1 #aeh1 #aei1 #adh ,fig4 #aea shows cross-section of a plate-girder over-line bridge1 #bh feet span1 carrying a public road1 #ce feet wide1 over a double-line railway4 ,the main girders1 #b feet #d inches deep1 are placed at #e feet #b inch centres1 and are tied together by plate-iron cross-bracing #b feet deep4 ,jack-arches of brickwork1 #i inches thick1 are built in between the main girders1 the haunching being filled in with concrete4 ,the entire surface is covered over and made watertight with asphalte1 on which is laid the metalling of the roadway4 ,the outside girders are made considerably deeper1 and have strong cast-iron-plate parapets bolted on to the top booms4 ,there is no doubt that jack-arching of brickwork or concrete makes a very strong and permanent floorway1 but its dead weight is very great1 and its adoption is not to be recommended #adg where iron or steel plate troughing can be obtained at a moderate price4 ,fig4 #aeb gives cross-section of plate-girder over-line bridge1 #da feet #f inch span1 carrying a public road1 #be feet wide1 over three lines of way4 ,two main girders are used1 of sufficient depth to form parapets or screens for the finished roadway4 ,plate cross-girders1 placed at #f feet #f inch centres1 are riveted to the web-plate and lower angle irons of main girders2 and on these is placed a flooring of plate-iron longitudinal troughing to carry the metalled roadway4 ,fig4 #aec gives the particulars of a plate-girder over-line bridge1 carrying an important public road1 #ce feet wide1 over several main lines and sidings4 ,the carriage-way is carried by two girders placed at #be-;foot centres1 and on the lower boom of these are riveted lattice-work cross-girders to receive the plate-iron longitudinal troughing and roadway4 ,the footpath girders are set at a higher level1 and the load placed on the lower flange4 ,the curved side brackets merely act as bracing between the carriage-way girders and footpath girders4 ,a cast-iron-plate parapet is bolted on to the top of each of the footpath girders1 making a close screen1 #f feet high1 above the footpath4 ,lattice-work cross-girders were adopted for the convenience of supporting small water mains and gas mains below the road-level4 ,the roadway is formed of ordinary metalling1 and the footpaths of asphalte pavement2 the kerbing is of granite1 and the side water-tables of crushed granite concrete4 ,illustration3 ,fig4 #adi1 #aej1 #aea1 #aeb ,fig4 #aed is a cross-section of a small uncovered lattice-girder footbridge #da feet span1 and #e feet wide1 suitable for small roadside stations4 ,the top and bottom flange consist each of two angle irons1 those in the bottom flange being placed table side upwards1 so as to bring the entire section of both angle irons fairly into play1 and also to provide a better bearing for the channel-iron cross-girders which carry the planking of the footway4 ,when planking is carried on the inside of light angle iron1 as in ,fig4 #aee1 a severe strain is produced at the point ,a2 this is entirely obviated by placing the bottom angle irons table side upwards1 as in ,fig4 #aef4 ,three of the channel-iron cross-girders are extended outwards1 and to the ends of these are riveted tee-iron stiffeners to steady the main girders4 ,in some cases stamped1 or ribbed1 wrought-iron plates are used for a footway1 but1 although more durable1 they do not give such a secure or #adi agreeable foothold as timber4 ,the ascent or descent of the bridge may consist either of steps and landings1 or of ramps1 according to circumstances or expediency4 ,sometimes these bridges are made with curved tops1 terminating in steps when nearing the steps1 or ramps4 ,it is very questionable whether such an arrangement is a good one or a safe one4 ,there is always a feeling of insecurity when walking over a sloping surface broken up by steps1 and experience points out that it is better to continue the footway level right across to the place where the passenger must change his direction to go down the stairs or ramp4 ,fig4 #aeg gives cross-section of a covered lattice-girder footbridge1 #fb feet #f inches span1 and #aj feet wide1 suitable for an important station4 ,the upper boom of girder consists of two angle irons and top plate1 and the bottom boom of two channel irons4 ,the cross-girders are rolled joist-irons resting on the top tables of the channel irons4 ,four of the cross-girders are extended outwards1 and carry plate-iron outside vertical brackets to stiffen the main girders4 ,three-inch longitudinal planking is laid down from end to end of the bridge1 and on this is laid #a-;inch transverse flooring1 in narrow widths1 to form the walking deck4 ,the footbridge is lighted from the sides by continuous glazed sashes fixed in strong wooden framework1 as shown4 ,the roof is covered with canvas bedded in white lead1 and painted in the same way as an ordinary carriage roof4 ,the above examples of under-line and over-line bridges are given more with a view of illustrating some of the many different descriptions of flooring1 rather than to point out or suggest the type of main girder to carry the load4 ,the description and size of the main girders can be varied to suit the span of the bridge1 the requirements of the traffic1 and the opinion of the designer4 ,for spans up to #ej feet it will generally be found that web-plate girders are both simpler and cheaper than lattice or truss girders2 at the same time1 there are occasions where plate girders can be advantageously adopted for very much larger spans1 as1 for instance1 in the example given in ,fig4 #ade1 where the deep plate girders form a most efficient screen4 ,illustration3 ,fig4 #aec ,figs4 #afj to #aid give diagram sketches of a few out of the many forms of open1 or truss1 girders which have been adopted for large spans4 ,there are many types from which to make a selection1 each one possessing its own special features and advocates4 ,in working out the #aea details of any1 or all of them1 there are some points which should always be kept in mind when deciding the distribution of material in the main booms4 ,rain-water1 or moisture of any kind1 is the great enemy of wrought-iron or steel work1 and therefore the plates1 angles1 tees1 or channel sections1 should be so arranged as to afford the least possible facility for the collection or lodgment of water4 ,with open1 level booms1 as in ,figs4 #acg1 #aci1 #adj1 #add1 and #ade1 the rain-water cannot collect1 but runs off at the sides1 and the plates are quickly dried by the sun and wind4 ,with trough booms1 as in ,fig4 #aeh1 the collected rain-water can only get away through holes drilled for the purpose in the bottom plates4 ,these holes are liable to become choked up1 but even when open they rarely carry off all the accumulated water2 some of it remains to corrode the plates1 and is only dried up by evaporation4 ,the inside of trough booms should be constantly inspected1 and the exposed plates more frequently painted than the rest of the girder4 ,in a similar manner1 in small double-web lattice girders1 with the lattice-bars inserted between two angle irons1 as in ,fig4 #aei1 the rain-water finds its way into the spaces at ,a1 ,a1 in spite of the most careful packing or filling with cement or asphalte4 ,numbers of small girders of this latter type have had to be taken out after a comparative short life1 in consequence of the great corrosion and wearing away of the lower ends of the lattice-bars and angle irons into which they were inserted4 ,it is most essential1 also1 that all portions of the girder-work should be conveniently accessible for inspection and painting4 ,complicated connections1 and parts which are difficult to examine1 are liable to be overlooked1 or1 at the best1 only painted in a very imperfect manner4 ,neglected corners soon create deterioration1 the paint scales off1 corrosion commences1 and the working section is gradually reduced4 ,a discovered weakness in some of the important parts points to an early condemnation of the entire structure4 ,the difficulty of access to the interior of box or tubular girders1 especially those of small or moderate dimensions1 is a great objection to that type of girder4 ,experience has pointed out that open girders1 free and exposed to the light and air1 can be so much more effectually inspected and painted4 ,illustration3 ,fig4 #aed1 #aee1 #aef1 #aeg ,illustration3 ,fig4 #afj1 #afa1 #afb1 #afc1 #afd1 #afe1 #aff1 #afg1 #afh ,illustration3 ,fig4 #afi1 #agj1 #aga1 #agb1 #agc1 #agd1 #age1 #agf ,illustration3 ,fig4 #agg1 #agh1 #agi1 #ahj1 #aha1 #ahb1 #ahc ,illustration3 ,fig4 #ahd1 #ahe1 #ahf1 #ahg1 #ahh1 #ahi1 #aij1 #aia ,illustration3 ,fig4 #aib1 #aic1 #aid ,perhaps one of the most anxious tasks which falls to the lot of an engineer is the renewal of under-line bridges and viaducts on a working line4 ,on a new line in course of construction the entire site #aeh of the work is at the disposal of the erectors1 and the building of a bridge or viaduct can be carried on with a freedom which cannot be obtained on an open line4 ,on a working railway1 the train service must be kept going1 irrespective of renewals1 and very often the best that can be done is to reduce the double line to single line working at the site of the operations4 ,it is not always expedient or possible to make a temporary bridge and diverted line for traffic purposes1 as the expenditure to be incurred might be too great to warrant the outlay1 or there may be local difficulties to effectually prevent the introduction of a provisional structure4 ,the taking down of one half of the old structure may necessitate the removal of stays and bracing affecting the stability of the half remaining to carry the traffic1 and thus render temporary shoring and bracing necessary4 ,the erection of the new work in such a limited space has to be watched with great care2 all cranes1 lifting appliances1 and scaffolding must be kept clear of vehicles moving over the running-line1 and very frequently it is found prudent to cease erecting operations during the passage of a train4 ,in very many cases of renewals1 the description and arrangement of the old structure will materially influence or control the design for the new one1 and the details of the latter must be schemed out so as to disturb as little as possible the stability of the old work remaining as the working road4 ,the following list gives the lengths of the main spans of some railway bridges1 and may be found useful for reference3-- ,,lengths ,,of ,,main ,,spans ,,of ,,some ,,large ,,railway ,,bridges4 ---------------------------------------- ------------------ ,name4 ,span4 ,description4 ---------------------------------------- ------------------ feet4 ,forth ,bridge #a1gaj ,cantilever4 ,niagara #hba ,suspension4 ,sukkur #hbj ,cantilever4 ,poughkeepsie1 ,u4,s4,a4 #edh ,cantilever4 ,douro #ebe ,arch4 ,st4 ,louis #ebj ,arch4 ,cincinnati #eae ,linville truss4 ,haarlem #eaj ,arch4 ,kuilemburg #dib ,lattice bow4 ,st4 ,john's ,river #dgg ,cantilever4 ,niagara #dgj ,cantilever4 ,britannia #dfj ,tube4#aei ,ohio ,river1 ,pennsylvania #ddb ,pratt through truss4 #aei ,saltash #dcd ,tube and girder4 ,hawkesberry ,viaduct #daj ,compound truss4 ,conway #djj ,tube4 ,vistula #cig ,lattice4 ,spey ,river1 ,garmouth1 ,n4,b4 #cej ,bowstring4 ,st4 ,laurence #ccj ,tube4 ,hamburg #caf ,double bow4 ,cologne #cac ,lattice4 ,runcorn #cje ,lattice4 ,sunderland #cjj ,bowstring4 ,rondout ,bridge1 ,buffalo #bfd ,pratt through truss4 ,newark ,dyke 7,new7 #bei ,lattice bow4 ,tay ,bridge 7,new7 #bde ,lattice bow4 ,ohio ,river1 ,louisville #bde ,fink truss4 ,beaver ,bridge1 ,pennsylvania #bcj ,pratt deck truss4 ,craigellachie ,bridge #bjj ,lattice4 ,rohrbach ,bridge1 ,st4 ,gothard ,river #aig ,wrought-iron arch4 ,windsor ,bridge #ahg ,bowstring4 ,victoria ,bridge over ,thames #age ,wrought-iron arch4 ,shannon ,river ,bridge #afe ,bowstring4 ,carron ,bridge over ,spey #aej ,cast-iron arch4 ,preston ,viaduct #ajb ,cast-iron arch4 ,trent ,river ,bridge #ajj ,cast-iron arch4 ---------------------------------------- ------------------------ ,retaining ,walls4--,instances frequently occur during the construction of a railway where it is advisable1 if not absolutely necessary1 to substitute retaining walls in preference to forming the slopes of cuttings and embankments4 ,the excavation of a cutting may be greatly reduced in quantity by introducing low retaining walls1 as in ,fig4 #aie1 and the saving in the material to be removed will be all the more important in those cases where cutting is in excess of embankment4 ,the amount of filling for an embankment and the land on which it has to be formed may both be considerably diminished by building a low retaining wall1 say #f or #g feet high1 at the foot of the slope1 as shown in ,fig4 #aif4 ,such a retaining wall makes a most efficient fence and well defined boundary of property4 ,illustration3 ,fig4 #aie1 #aif1 #aig1 #aih1 #aii1 #bjj1 #bja ,the policy of adopting low retaining walls in cases like the above #afa will depend mainly upon the cost of building materials as compared with the cost of earthwork and land4 ,where land is very valuable1 and where residential property1 streets1 or roads must be interfered with as little as possible1 the retaining walls may have to be carried up to the level of the original surface of the ground1 as in ,fig4 #aig1 which is shown as for a cutting #be feet deep4 ,the walls may be built of masonry1 brickwork1 or concrete1 or a combination of them1 and the dimensions or thickness will depend upon the description of material to be supported4 ,weeping holes1 or small pipe drains1 should be formed in the walls1 a little above formation level1 to take away any water which may collect at the back4 ,where the cutting is through soft1 wet1 treacherous clay1 liable to slip or expand1 it may be necessary to insert arched thrust girders extending from side to side1 as in ,fig4 #aih1 so that the outward pressure against the one wall may counteract against the outward pressure of the other4 ,the thrust girders should be placed at from #aj to #ae feet centres1 and be well braced together in plan to enable them the better to resist any tendency of bulging out of the walls4 ,a similar arrangement of high retaining wall may be introduced in embankment to lessen the encroachment on streets or public roads1 as shown in ,fig4 #aii4 ,in making a railway through thickly populated towns1 it is generally preferable to construct the line on arches rather than on earthwork filling between two high retaining walls4 ,the numerous openings are available for future streets1 or means of communication from one side to the other1 and the arches themselves can be profitably utilized for stables1 stores1 offices1 and workshops4 ,fig4 #bjj shows a narrow rocky pass with deep rapid river on the one hand and high cliffs on the other1 the only available ledge being already occupied by a public highway4 ,by building a retaining wall1 as indicated on the sketch1 and excavating a little out of the cliff1 space may be obtained for a line of railway2 or the arrangement may have to be reversed1 and the retaining wall for the railway built along the margin of the river1 as in ,fig4 #bja4 ,in both the cases1 ,figs4 #bjj and #bja1 not only must there be a number of weeping holes left in the lower part of the wall1 but there must be sufficient well-built drains and culverts under the filling and through #afb the wall to carry away all ordinary or flood water coming down from the cliffs and hills above4 ,where a retaining wall is built along the margin of a river1 the lower portion1 which will be in contact with the water when the river is full1 should be constructed of selected large heavy stones to withstand the scouring action of the water1 and any brushwood or floating timber which may be brought down by flood water4 ,where retaining walls are built to support wet clay1 or in embanked places on wet side-lying ground1 the efficiency of the work will be much increased by constructing a layer1 two or three feet in thickness1 of dry1 flat1 bedded stones carefully hand-laid1 from the foundation to the top of the wall1 as shown in ,fig4 #aii4 ,these dry stones form a continuous vertical drain to take away water from any part of the earthwork down to the outlets left in the lower portion of the wall4 ,the building of retaining walls entirely of dry stone is very questionable economy1 and entails a constant expenditure in maintenance and renewal4 ,the working out of one stone loosens the surrounding portion of the wall1 and if not at once repaired1 a length of the wall will fall down1 bringing with it a large quantity of the earthwork4 ,if readily obtained1 large heavy stones should be selected for the coping of retaining walls1 so as to minimize as much as possible the chance of their disturbance or displacement4 ,where lighter stones have to be used1 or bricks laid on edge1 they should be bedded and pointed in cement4 ,in many places it is necessary to form wide and massive foundations of concrete on which to build the retaining wall2 and in some cases of soft1 treacherous ground1 timber piling may be necessary4 ,tunnels4--,it would be difficult to assign a date to the first examples of subterranean works constructed for utilitarian purposes4 ,nature had furnished so many grand specimens of caves1 grottoes1 and underground passages formed in the solid rock1 that man soon grasped the principle1 and essayed to carry out similar works on his own account4 ,the early attempts would probably be limited to forming places of shelter1 storage or security4 ,advantage would be taken of those rocks which from their locality1 accessibility1 and compactness of material1 promised favourable results4 ,the appliances being few and primitive1 the work of construction would be laborious and slow4 ,so #afc long1 however1 as the workers restricted their operations to the solid rock1 they had merely to contend against the hardness of the material1 as the opening or passage-way1 once made1 required no further support or attention2 but as the wave of progress swept onward1 man was compelled to deviate from the lines originally followed by nature1 and had to form his subterranean pathway through softer material1 where the workings required substantial support4 ,the search for minerals of various kinds led to the driving of long headings or galleries underground1 and as these had frequently to penetrate through strata of a soft and yielding character1 strong timber framework had to be introduced to afford stability to the works1 and safety to the workers4 ,for ordinary mining operations1 strong rough timber supports may meet all requirements1 and may last until the heading is worked out and abandoned2 but for subterranean passages or tunnels which are intended to form permanent means of communication1 the strongest and most durable materials must be used to protect the interior as far as possible from deterioration or decay4 ,heavy timbering might be sufficient for mere temporary purposes1 but substantial masonry or brickwork side walls and arching became necessary for permanent work in those portions where the tunnel required artificial support4 ,the first tunnels of any importance were most probably those constructed for canal purposes4 ,many of them were of considerable magnitude1 and in some instances were from two to three miles in length4 ,they were substantially lined with masonry or brickwork at all places where the tunnel passed through soft material or loose rock1 and from the solid nature of the work1 and the many years they have been in existence1 they thoroughly testify to the ability of the constructors4 ,the introduction of railways involved the making of a large number of tunnels1 perhaps more so in the beginning1 when it was thought that the use of the locomotive would be confined to very moderate gradients1 and when engineers hesitated to adopt the steeper inclines and sharper curves which form the practice of modern times4 ,another element of consideration also consisted in the fact that the first railways were designed to connect the most populous and busiest districts1 where the prospects of heavy traffic would appear to warrant a large outlay for works of construction4 ,as the system spread and railways extended further away from the important centres1 the #afd probabilities of traffic would become less promising1 and efforts would be made to keep down cost of construction1 and avoid tunnel work as much as possible4 ,it is not easy to define where cutting should end and tunnelling begin4 ,there is no practical difficulty in making a cutting #ej1 #fj1 or #gj feet deep1 with slopes to suit the material excavated1 and the estimated cost per yard forward may even compare favourably with the cost of average tunnel-work4 ,but there are other questions which must be kept in view--the time required to form the cutting1 the space to be obtained on which to deposit the enormous quantity of excavated material1 and the probable difficulty in obtaining the large area of land necessary for the cutting4 ,before deciding the actual position of a tunnel1 both as to line and level1 it is necessary to obtain the most reliable information possible regarding the strata through which it has to pass4 ,in addition to the geological indications on the surface and in the locality1 borings should be made1 and trial holes or shafts sunk along the proposed centre line of the work1 and from these an approximately accurate longitudinal section can be laid down on paper1 showing the respective layers of material to be cut through1 and the angle at which they lie4 ,with these particulars before him1 the engineer may1 in some cases1 consider it more prudent to change the position of the tunnel in preference to incurring specially difficult or tedious work in dealing with some recognized unfavourable material4 ,occasionally the route may be slightly varied and better material obtained1 but very frequently there is little to be gained except by a wide deviation from the original line4 ,solid rock1 except for the slow progress1 is perhaps the most favourable material for tunnelling1 as the timbering1 side walling1 and arching can be almost1 if not entirely1 dispensed with4 ,loose rock1 although more readily removed1 necessitates strong timbering to prevent large masses breaking away and falling into the tunnel4 ,some clays are very compact and tenacious1 and will stand well with moderate timbering1 but even these should not be left long before following up with the side walls and arching4 ,many clays give much trouble by expanding1 or swelling out1 when the excavation penetrates the layer1 and although extra strong timbering #afe may be used1 and be placed closer together1 the logs and planks are frequently bulged out and broken by the action of the clay4 ,specially strong supports are required for this description of clay1 and extra thickness of material in the permanent work of side walls and arching4 ,solid unbroken beds of chalk are not difficult to cut through3 the material is easy to work1 and the excavation will stand with ordinary timbering2 but where the chalk is broken and intersected with deep pockets of gravel and sand1 the operations are very much impeded4 ,the loose material1 once set free by cutting through the confining barrier of chalk1 will quickly fall into and fill up the excavation if not held back by strong timbering4 ,side walls and arching are generally necessary for tunnels through chalk4 ,soft wet clay1 quicksands1 or other strata having springs of water percolating through them1 are serious obstacles in the way of expeditious tunnelling4 ,no sooner is one cube yard of this soft material removed than another slides down1 or is washed down1 to take its place4 ,when once the excavation taps the water-bearing strata1 large volumes of water will find their way into the workings1 and must be conveyed away to the mouth of the tunnel1 or pumped up through the nearest shaft4 ,the timbering of the sides and roof through this description of working is very tedious1 and attended also with a considerable amount of risk4 ,the absence of really solid ground on which to place or shore up the supports1 taxes the skill of the excavators1 and very often1 when a short length has been made apparently secure1 it will come down with a run1 compelling all hands to beat a hasty retreat4 ,the permanent lining through such treacherous material should follow the excavation very closely1 and special care should be exercised in building the walls1 arching and invert4 ,in the excavation through stratified rocks it is necessary to note carefully the lie of the strata1 whether horizontal1 vertical1 or shelving1 as with each one the excavators are exposed to risks1 against which every precaution should be taken4 ,a large horizontal slab of solid-looking rock will suddenly break and fall down without any warning4 ,a heavy mass from a vertical layer1 perhaps unkeyed1 or loosened1 by an adjacent blasting operation1 drops down when least expected2 and pieces from the high side of the shelving layers detach themselves and slide into the working in a most unaccountable manner4 ,no attempt should be made to carry a tunnel through material which has #aff been disturbed or at all affected by any natural slip or cleavage1 as although the strata may be hard and compact in themselves1 they have really no solid or fixed foundation4 ,the sliding away1 once initiated1 is certain to continue1 and1 accelerated by the tunnelling operations1 will most likely1 sooner or later1 crush in the tunnel and sweep away every vestige of the work4 ,amongst the great mountain ranges these natural disturbances are by no means rare1 and it will be wiser to keep away from their locality1 even at the expense of a longer tunnel4 ,unfortunately1 instances are on record of tunnels made1 or in course of construction1 through hillsides which had already commenced to slide away from the more solid rock1 and the ultimate results were a further sliding away and total destruction of the work4 ,the lower slopes and outlying portions of high mountains are the most exposed to these natural slips1 and they should be most carefully studied before commencing any tunnelling operations through them4 ,to facilitate drainage1 it is essential that a railway tunnel should be laid down with a gradient or gradients falling in the direction of one or both ends of the tunnel4 ,in nearly all tunnels a considerable amount of water finds its way in through the weeping-holes left for that purpose in the side walls1 and must be carried away in suitable drains4 ,if the quantity of water be small1 ordinary water-tables1 one on each side1 may be sufficient2 but for large volumes of water it will be necessary to build substantial side-drains1 or an ample culvert below the level of the rails4 ,the gradients in a tunnel should be moderate1 and not by any means excessive1 or likely to tax the hauling powers of the locomotives4 ,when an engine is working nearly to the utmost of its power on a steep tunnel incline1 and the speed has become very slow1 the exhaust vapours or gases from the funnel strike the arching with great force1 and are deflected down on to the footplate in such dense volumes as to almost suffocate the driver and fireman4 ,the writer will never forget two or three trying experiences in foreign tunnels1 when he and the engine-staff were compelled to leave the footplate and climb forward to the front of the funnel1 leaving the engine to work its way alone4 ,except for very short tunnels it is wiser to have easy inclines1 and to restrict the steep gradients to the open line1 where the very slow #afg travelling1 or even the coming to a stand from 8slipping10 may not produce unpleasant or alarming consequences4 ,in tunnels of any length it is usual1 where possible1 to construct shafts extending from the surface of the ground overhead down to the tunnel below4 ,these shafts serve the double purpose of enabling the excavation to be carried on at an increased number of faces1 and act as permanent ventilators after completion4 ,in some cases the shafts are sunk exactly over the centre line of the tunnel1 in others a few yards away from the centre line4 ,the latter arrangement1 if not quite so convenient for hoisting material while carrying on the excavations1 has certainly the great after advantage that anything falling or maliciously thrown down the shaft cannot strike a passing train4 ,the short side-gallery1 or space between the tunnel and the shaft1 provides a good refuge for workmen employed in repairs1 and a convenient site for storing a few materials advisable to keep on hand4 ,occasionally favourable opportunities present themselves for making horizontal shafts4 ,for a portion of its length the tunnel may be located at no very great distance from the precipitous sides of some deep mountain ravine1 or run near to the cliffs on the sea-coast1 and advantage can be taken to drive a lateral heading or gallery through which the material from the tunnel excavation may be conveyed and thrown out into the gorge or seashore below4 ,in many cases the surface of the ground rises so abruptly from the faces of the tunnel and ascends to so great a height1 that shafts of any kind are entirely out of the question1 and the whole of the work must be carried on from the two ends4 ,the rate of progress is consequently much slower1 and the ventilation more difficult4 ,in a shaftless tunnel of considerable length1 and with a frequent train service1 the question of providing suitable appliances for promoting artificial ventilation is of the utmost importance4 ,when the centre line of the tunnel has been accurately set out on the ground1 and the levels of the different parts of the work decided1 the construction of the shafts and the driving of the headings can be commenced4 ,working shafts intended to serve for permanent ventilation are generally made nine or ten feet or more in diameter1 and are usually lined with substantial brickwork or masonry4 ,when the well-like #afh excavation has been carried down a few yards1 or as far as it can be taken without the risk of the earth falling in upon the sinkers1 a strong curb of hard wood or iron of the same diameter as the finished shaft is laid down perfectly level and to exact position1 and on this curb the ring or lining of brickwork or masonry is built up to the level of the ground4 ,the first length finished1 the excavation downwards is resumed1 and the interior lining continued1 either by allowing the first length to slide down as the material below is gradually removed1 and building further lining on the top1 or by excavating and propping up the curbing with strong timbers below4 ,when working to the latter method1 stout wooden props of convenient length1 stepped on to sole-pieces1 are adjusted to the under side of the wooden curb above1 the material is then removed for the thickness of the brickwork or masonry1 and another curb accurately set to level and position2 on this is built a length of lining up to the first curb4 ,this work of under-building or under-pinning must be carried out with great care and in segments2 no props must be removed until the curb immediately above is well supported by the new lining1 and the inside of the lining must be watched and tested to prevent any tilting4 ,all spaces at the back of the work must be filled in and well packed with hard dry material4 ,as the shaft is continued downwards the mode of working may have to be varied2 different descriptions of material may be encountered1 and blasting1 shoring1 and pumping may each in turn be necessary4 ,when down to the full depth1 the lower length of the shaft will have to be securely supported by strong timbers1 until it can be properly built into and incorporated with the arching of the tunnel or side gallery4 ,the completion of the shaft enables the workings to be commenced on each side1 the excavated material can be hoisted to the surface1 and building material lowered down4 ,when the tunnel works are finally finished1 the lining of the shaft should be carried up until it is #ae or #bj feet above the level of the surface of the ground1 and a dome-shaped iron grating placed on the top as a protection against stones or other articles which malicious persons might attempt to throw down the shaft4 ,some shafts are only intended for the temporary purpose of lifting the excavations from below1 or lowering building materials down1 and when #afi the work is completed they are filled in again and closed4 ,these service shafts are generally made square in section1 and are merely lined with wood4 ,strong vertical timbers are placed at the four corners1 to which horizontal double cross-pieces are bolted1 thick planking being placed vertically at the back of these cross-pieces to support the sides of the excavation4 ,the heading of a tunnel is a narrow passage or gallery cut through from end to end of the works in the direction of the centre line4 ,where there are shafts1 the cutting of the heading can be pushed on from several points1 and be completed much more rapidly than when the working is restricted to the two ends4 ,headings are usually made just sufficiently large for the miners to work1 say about #e feet #f inches high by about #c feet wide1 the object being rather to expedite the driving of the driftway than to remove large masses of material4 ,they must be set out with great accuracy1 and be constantly checked as the driving is in progress4 ,when completed from end to end1 the centre line can be checked throughout1 and the course actually taken compared with the course intended4 ,if there has been much variation in the narrow pioneer pathway1 either in line or level1 the amount of the divergence must be rectified when ranging the final centre line for the full-size excavation4 ,tunnels cannot always be delayed until the heading is cut through for the entire length4 ,in many cases the heading1 the full-size excavation1 and the permanent lining have all to be carried on at the same time1 but as the work of the heading is smaller in extent1 that portion of the operations can usually be kept well in advance of the others4 ,the critical moment arrives when the headings from opposite directions meet1 as any deviation or want of coincidence must be adjusted in the portion of the tunnel still remaining to be opened out to full size4 ,some tunnels of moderate length have been constructed without any heading at all1 the excavation being taken out to the full dimensions from the commencement4 ,the heading of a tunnel assists not only in the correct alignment of the work1 but furnishes at the same time an accurate knowledge of the strata passed through4 ,it is also of service for ventilation1 communication1 and drainage4 ,in some cases the heading is driven at the bottom of the tunnel section1 as in ,fig4 #baa1 and in others at the top1 as in ,figs4 #bjb and #agj #bjd4 ,many of the earlier tunnels were constructed on the former system1 while of late years the latter method has been very largely adopted4 ,the bottom heading may perhaps in some instances be more efficacious for drainage1 but it is very liable to be frequently choked up when taking out the excavation to the full size1 and the lower surface is much cut up by the movement and conveyance of materials4 ,another disadvantage arises from the necessity of removing such a large amount of the cutting approaching the tunnel entrance before a beginning can be made to the bottom heading4 ,the top heading has the advantage that it requires less removal of open cutting previous to its commencement1 and1 being high up in position1 there is less chance of its being stopped up by falling material1 the finished excavations being carried out on the sides and below the heading4 ,where the headings are cut through solid rock1 stiff shale1 or compact chalk1 little or no supports are necessary1 but where they pass through clay or loose material1 timbering will be required for sides1 roof1 and floor4 ,rough round poles1 about #f inches in diameter1 are generally used for verticals1 and are firmly secured to transverse sole-pieces1 and on the top of these verticals strong transverse top-sills are fastened by means of rough tenons or checks4 ,strong boards are inserted at the back of this framework to keep the earth from falling into the working4 ,the distance apart of the verticals will depend upon the description of material excavated2 in very soft places they will have to be placed very close together1 but where fairly sound and tenacious they may be placed at about #c-;foot centres4 ,the excavated material must be conveyed away to the entrance of the heading in small hand-trucks running on planks or light rails4 ,the widening out of the excavation to the full size will be a repetition on a large scale of the work carried out in the heading1 with the difference that1 the exposed surfaces being of so much greater extent1 extra care and precautions must be taken with the framework and shoring of the timbering4 ,illustration3 ,fig4 #bjb1 #bjc ,the form and arrangement of the timbering1 as well as the number1 sizes1 and positions of the pieces1 must be determined by the material of the excavation and the contour line of the finished arching or lining4 ,the framework1 which would be sufficient to support ordinary soft material1 must be largely augmented both in quantity and scantling #agb to meet the requirements for wet treacherous clay4 ,figs4 #bjb and #bjc give end view and longitudinal section of timber framework frequently adopted for average tunnel work4 ,the positions of the different pieces will explain themselves and the duty they have to perform4 ,the main struts1 or raking pieces1 which have to sustain great pressure1 may be shored against the finished lengths of masonry or brickwork4 ,the timbering of the sides can be removed as the lining proceeds1 but in many cases the round logs and boards near the crown cannot be withdrawn1 and have to be left in the work1 the space between the top of the arching and under side of the boards being firmly packed with brickwork1 masonry1 or dry rubble stonework4 ,as the tunnel lining is generally carried forward in short lengths1 following up the main excavations1 the centering for the arching should be of such description that it can be readily transferred or moved forward as the work proceeds4 ,the form of the centering1 and the spacing of its upright supports1 must admit of sufficient width for one or more lines of rails for the waggons required to remove the excavated dbris and convey the building materials used in the lining4 ,picks1 bars1 and shovels are the tools used in the excavation of the softer material and loose disintegrated rock1 but for the hard rock1 blasting will be necessary4 ,the tunnel opening being comparatively small1 only moderate blasting charges can be used with safety1 and these must be placed so as to break up the rock-bed in a suitable manner for working1 and without shaking or damaging the already completed excavation4 ,ordinary hand-drills1 or jumpers1 may be used for forming the charge holes1 a number of them being at work at the same time1 and the charges fired very closely one after the other4 ,as the blasting operations necessitate the retiring of the miners to a considerable distance1 out of the way of flying fragments1 and the remaining away until the foul air has been dispelled1 it is advisable to fire off several charges about the same time1 and thus minimize as much as possible the stoppage to the drilling and clearing away the loosened material4 ,illustration3 ,fig4 #bjd1 #bje1 #bjf1 #bjg1 #bjh1 #bji1 #baj1 #baa ,mechanical drills1 worked by compressed air or other motive-power1 are now very extensively used where the rock is solid and continuous4 ,they are much more expeditious than the hand drills1 but they are costly in #agd their installation1 and also in their working and maintenance4 ,in some tunnels1 where the material has been firm and dry1 the upper portion of the excavation has been first removed1 and the masonry and brickwork lining built in position down to about the springing of the arch1 the remainder of the excavation being afterwards taken out1 and the side walls built by means of shoring and underpinning4 ,in other tunnels the complete section has been excavated and timbered1 and the work of building commenced from the foundation of the side walls4 ,a strong continuous invert from side wall to side wall is necessary where passing through soft swelling clay or loose strata intersected with small streams of water4 ,where the material is very solid and dry1 it is not necessary to introduce inverts1 but the foundations of the side walls should be laid at such a depth below rail-level as not to be affected by drain-water running through the tunnel4 ,the side walls and arching may be either of masonry or brickwork1 but should be of the best description1 especially for the facework4 ,for brick arching only the best hard-burnt bricks should be used1 and the inner or exposed ring should consist of selected hard fire-bricks to withstand the heat and gases escaping from the funnels of the locomotives4 ,the thickness of the side walls and arching will depend upon the description of material to be supported4 ,in some places a comparative thin lining may be sufficient1 while in others extra thickness must be given to resist the great pressure exerted by expanding clay and loose wet strata4 ,weeping-holes1 or small drain-pipes1 placed low down must be left in the side walls every three or four yards1 or closer in very wet places1 to allow the water collected at the back of the walls to escape into the side drains of tunnel4 ,in building the arch portion every effort should be made to have close solid work without any open joints or spaces through which the water may run1 and the crown of the arch and a few feet down on each side should be coated with cement or asphalte to lead all water away from the top to the sides4 ,water dripping from the under side of the arch on to the line is a great destructor of the permanent way materials1 especially the fastenings2 and bolts1 nuts1 fish-plates1 and spikes placed in a wet dripping tunnel will not last half the time they would out in the open line1 where they would have the sun and wind to dry them4 ,illustration3 ,fig4 #bab1 #bac1 #bad1 #bae1 #baf1 #bag1 #bah1 #bai ,small arched recesses or niches should be formed in the side walls at #agf convenient distances to serve as refuges for platelayers or others working in the tunnels4 ,it is most essential that the space between the masonry and brickwork lining and the facework of the excavation should be carefully filled in and hard packed1 so as to prevent the possibility of pieces of rock or other material falling on to the top of the arch4 ,the neglect of this precaution may lead to a casualty years after the tunnel has been completed4 ,it would be impossible to over-rate the importance of a constant faithful supervision of the building of the lining1 especially the arching4 ,the work has to be carried on by workmen in cramped positions1 with imperfect light1 and surrounded by all kinds of obstacles and inconveniences1 and unless a detailed inspection be rigidly maintained1 a carelessness in the selection of the materials1 and a laxity in the workmanship1 will be the inevitable result4 ,figs4 #bjd to #bai are sections of tunnels which have been constructed for double and single line railways4 ,the sections give the normal form and dimensions adopted in each case1 although there may have been many portions of the work where unfavourable or treacherous material necessitated an increase in the thickness of the side walls1 or of the arching1 or of both4 ,the types vary in accordance with the opinions of the designers as to the most suitable section for the purpose1 and range from the comparatively thin lining and vertical side walls shown on ,fig4 #bjg1 to the almost circular form and very thick lining shown on ,fig4 #baf4 ,the latter is the section which experience has proved to be the best to sustain the enormous all-round pressure exerted by certain descriptions of swelling clay4 ,careful judgment will be required to decide which parts of a rock tunnel may be left unlined4 ,the apparently solid-looking portions are oftentimes deceptive1 and numbers of instances are on record of large pieces of rock falling down in tunnels which for many years had been considered as thoroughly secure4 ,where there is any doubt it is better and safer to put in a lining1 even if only to the extent of an arching springing from side walls of solid rock1 as shown on ,fig4 #bjf4 ,a moderate additional expenditure at the time of construction may prevent a serious catastrophe afterwards4 ,illustration3 ,fig4 #bbj1 #bba1 #bbb1 #bbc ,the faces or entrances to tunnels may be constructed with curved wing #agh walls1 as in ,fig4 #bbj1 or with straight wing walls1 as in ,figs4 #bba1 #bbb1 and #bbc4 ,where the approach cutting is in rock1 the latter form is generally adopted4 ,it would be misleading to put down any average price for tunnel-work4 ,so much depends upon the locality1 the description of material to be excavated1 the cost of masonry or brickwork1 and the cost of labour4 ,added to these come the unforeseen troubles of slips and water-laden strata1 creating difficulties which baffle the miners for a time1 and add enormously to the expenditure4 ,some tunnels for double line have been constructed in good ground1 and under favourable circumstances as to building materials and labour1 for as low as #cb per lineal yard2 while others1 carried out under adverse conditions1 have cost as much as #aej per lineal yard4 ,a medium somewhere between the two should represent the cost of tunnel-work through ground which does not present any special difficulty4 ,at the same time it must be borne in mind that simple tunnelling which can be done in one locality for #ej or #fj per lineal yard1 would be increased #bj1 #cj1 or #dj per cent4 in another1 where building material for the lining is scarce and expensive4 ,tunnel-work abroad will generally cost more than the same work at home4 ,the native labourers may perhaps be procured at low rates1 but the skilled workmen must be brought from a distance1 and will obtain high wages4 ,another form of tunnel-work1 generally termed the covered-way system1 is frequently adopted in towns and places where land and space are very valuable4 ,this method consists in the excavating and removing of earthwork to admit of the building of the side walls and arching of a suitable tunnel-way1 and then filling in over the top to a depth of three or four feet1 or up to the level of the original surface of the ground4 ,this work may be carried out by either removing the entire width of the earthwork before the commencement of any building operations1 or by first forming two deep1 well-shored trenches1 in which to build the side walls up to about arch-springing4 ,in bad ground the latter arrangement has the advantage1 as the shoring and strutting to hold up the sliding material is limited to the widths of the two narrow trenches1 and the centre block of earthwork is left untouched as a support to the strutting4 ,when the side walls have been built sufficiently high the upper portion of the centre block of earthwork can be removed to allow of the erection of centering and #agi building of the arching1 and afterwards the remaining portion of earthwork can be removed at convenience4 ,in this manner a tunnel-way may be constructed under streets1 gardens1 and even under buildings4 ,being nearly all done in the open1 the work is more under control than in an ordinary tunnel1 but it is usually very costly4 ,temporary or diverted roads must be arranged2 the excavated material must generally all be removed by carts1 sometimes to long distances2 and provision must be made for diverting the network of sewers1 gas1 and water pipes which are intercepted along the route4 ,fig4 #bbd is a sketch of covered-way with brick arching4 ,fig4 #bbe illustrates another type where cast-iron girders and jack-arches of brickwork were introduced on account of the small headway4 ,in soft yielding clay it is necessary to construct strong inverts1 as indicated in the sketches4 ,recesses for the platelayers should be provided every ten or fifteen yards4 ,the above systems of covered-way were largely adopted in the construction of the underground portions of the ,metropolitan ,railway and ,district ,railways in and around ,london4 ,illustration3 ,fig4 #bbd1 #bbe1 #bbf ,in addition to the ordinary type of tunnel formed by first excavating the material and then lining the opening with brickwork or masonry1 tunnels of moderate size have been constructed of cast-iron tubes1 similar in section to ,fig4 #bbf4 ,the tubes were cast in short segments1 bolted together inside1 the outer circumference1 or surface in contact with the earth or clay1 being left free from projections of any kind4 ,by making the segments with bolt-holes exact to template1 they were readily fitted together in the work1 and a thin layer of suitable packing material placed between the bolting-flanges sufficed to render the tubes water-tight4 ,the tunnelling was carried on by means of a short length of slightly larger tube1 or cap1 made of plate-iron or steel1 which fitted over the leading end of the main tube4 ,the front end of this cap was made very strong1 and provided with doors through which the miners could work4 ,a series of hydraulic presses attached to the cap were brought to bear on the bolting-flange of the last completed ring1 and as the excavated matter was removed by the miners from the front the cap was forced forward by the hydraulic presses1 and another ring of cast-iron segments inserted4 ,on the ,city and ,south ,london ,railway1 constructed on the above system1 the small annular space formed round the cast-iron tube by the operation of the sliding #aha cap was filled in with cement grouting by means of an ingenious machine designed for the purpose4 ,large tunnels under rivers or tidal estuaries must each be dealt with according to the particular circumstances of depth below stream-bed1 material to be cut through1 length of tunnel1 and gradient4 ,the chief obstacle to be contended against in so much of the river tunnel-work is the large volume of water which pours into the workings through fissures in rock or seams of gravel and sand1 necessitating the constant use of most powerful pumps4 ,in ordinary land tunnels the gradients are generally laid out to fall towards one or both entrances1 and any water finding its way into the excavations may be led away to the entrances by drains or pipes4 ,on the other hand1 in a river tunnel the gradients generally fall away from the entrances down towards the centre of the river1 and all water coming in must be pumped out and raised up to at least the level of the river4 ,in places where the water comes streaming in from many points1 any failure or stoppage of the pumps would place the lives of the miners1 and the security of the work itself1 in great jeopardy4 ,iron shields1 or protection chambers for the miners advancing the excavation1 have been used with great success in carrying on work through loose wet strata which appeared to defy all other means of progress4 ,solid rock1 chalk1 or compact clay1 may present no difficulty so far as they go1 but a continued dip in the gradient1 or a line of fault1 may suddenly change the entire course of operations1 and require the immediate use of the most powerful pumping machinery and protective appliances4 ,the special features of each case will demand special precautions1 and the judgment and inventive powers of the engineer will be severely tested in coping with the difficulties with which he is surrounded4 ,,chapter ,,iii4 #ahb ,permanent way--,rails--,sleepers--,fastenings--and ,permanent way laying4 ,rails4--,accustomed as we now are to the substantial character of the permanent way of our railways1 we can scarcely realize that in the earlier examples the rails or tram-plates were made of wood4 ,the first lines of which we find any record were those constructed to facilitate the conveyance of coal1 iron ore1 stone1 slate1 or other heavy materials to shipping ports or points of distribution4 ,speed was a matter of little importance1 the principal object being to introduce a distinct surface or roadway which would allow a heavier load to be hauled without increasing the hauling power4 ,as a heavily loaded wheelbarrow1 difficult to move on an ordinary road1 can be readily wheeled along a wooden plank1 so it may have been inferred that strong timber1 laid in parallel lines and level and even on the upper surface1 would form a track1 or roadway1 presenting far less resistance than the ordinary gravelled or paved roads4 ,the wooden tramway was the first improvement over the ordinary road4 ,the idea once originated1 various types were soon introduced1 and the sketch shown in ,fig4 #bbg illustrates one which appears to have been early suggested and largely adopted4 ,wooden cross-sleepers1 ,a1 ,a1 were placed at convenient spaces1 and on the top of these strong timber planks or beams1 ,b1 ,b1 were spiked at proper distances to suit the wheels of the waggons or four-wheel trucks1 which had flat tyres like ordinary carts4 ,the spaces between the sleepers were filled in with gravel or broken stone to form a roadway or hauling path for the horses4 ,a little later double rails were introduced1 by placing a second or upper timber on the top of the lower one1 as in ,fig4 #bbh4 ,illustration3 ,fig4 #bbg1 #bbh1 #bbi1 #bcj1 #bca1 #bcb1 #bcc1 #bcd1 #bce ,this double rail arrangement not only strengthened the framework1 but by increasing the height allowed a greater quantity of suitable #ahd material to be placed over the sleepers to protect them from wear by the horses' feet4 ,it can be easily understood that a wooden tramway could not be very durable4 ,it would be affected by the sun1 rain1 and snow1 and particles of sand and gravel thrown on to the tram beams from the hauling path would hasten the abrading or wearing away of the soft portions of the timber into hollows1 leaving the hard knots standing out as projections4 ,the uneven surface would produce a series of blows every time a loaded truck passed along1 loosening the pieces and rendering the repairs constant and expensive4 ,to obviate the rapid wear of the tram-timbers continuous narrow bars of wrought-iron were fastened on to the running-surfaces2 these in a measure prolonged the life of the timbers1 but at the same time added to the number of the pieces and fastenings to be maintained4 ,primitive as this description of road appears to be1 it was in use for many years in some parts of the ,united ,states of ,america1 and even after the introduction of the early locomotives2 timber was abundant and cheap1 and iron in any form was costly4 ,these long thin strips of iron1 placed as in ,fig4 #bcb1 had a tendency to become unfastened at the ends1 and to curl up in a very alarming manner1 which earned for them the soubriquet of snake heads4 ,although iron was only used to a limited extent in the first instance1 it was soon found to be a much more suitable material for a tram-path than the best timber4 ,as a next progressive step we find that the tram-plates were made entirely of iron1 of full width for the wheel-tyres1 and with a guiding flange to keep the wheels on the proper track4 ,in some cases the guiding flanges were placed inside the wheels1 as in ,figs4 #bbi and #bcj1 and in others outside1 as in ,fig4 #bca4 ,with the former plan a thicker covering of gravel or broken stones could be laid down to protect the sleepers under the horse-path4 ,these solid tram-plates were made of cast-iron1 that metal being considered the most convenient for manufacture and the least liable to suffer loss from rust and oxidization4 ,another advantage of the cast-iron was that broken tram-plates could be melted down and recast at a moderate cost4 ,long lengths of these cast-iron plate tramways were laid down in this country and abroad1 and short portions of some of them remain in existence even to the present day4 ,they were of immense service for #ahe the transportation of heavy materials1 and without their adventitious aid many valuable collieries and quarries must long have remained idle and undeveloped4 ,in thus providing a level1 smooth1 and comparatively durable wheel-track for the waggons1 these tramways became the fitting pioneers of the great railway system which was to follow4 ,notwithstanding the great superiority of the cast-iron plates as compared with the former timber beams1 much inconvenience was still caused by gravel and dirt falling on to the wheel-track and seriously impeding the haulage of the waggons4 ,to overcome this difficulty the next step taken was to remove the guiding flange from the tram-plate and transfer it to the wheel1 thus developing and introducing the original flanged wheel4 ,this was a most important step1 and paved the way for other improvements4 ,the rails1 or edge rails1 as they were at first called1 were made sufficiently high to allow ample space for the wheel-flanges to clear the ground1 and were secured to cast-iron chairs placed on wooden cross-sleepers1 or in some cases to stone blocks1 as shown in ,figs4 #bcc1 #bcd1 and #bce4 ,the narrow top of rail1 and its height above the horse-path1 effectually prevented the lodgment of gravel or dirt1 and the flanges on the wheels ensured a more even course4 ,from the irregular and easily choked-up tram-plate1 the system changed to the clean rail and properly defined track4 ,waggons could be hauled with greater freedom1 and with less wear and tear to themselves and to the roadway4 ,at this time the use of the steam-engine was becoming more general1 and a fine field was opened out for its application as a motive-power on the tramways4 ,stationary engines1 or winding engines1 as they were called1 were first employed to haul the trucks by means of long ropes passed round revolving drums1 and supported at intervals by grooved pulleys placed between the rails at suitable distances4 ,in this way fair loads could be conveyed1 and at moderate cost2 but the system was found to be only suitable for short distances1 and it had the great drawback that horses or other motive-power were still necessary for sorting or distributing the trucks before and after their transit by rope haulage4 ,the next great advance was to place the steam-engine on wheels1 to enable it to haul and accompany the trucks4 ,crude and imperfect as the primitive locomotives must have been1 a very short trial of them #ahf served to show that the rails of cast-iron then in use were totally unfitted to form a trackway for the newly invented machines4 ,the short fish-bellied cast-iron rails were made in lengths merely to extend from chair to chair2 they possessed little or no continuity1 and from the inherent brittleness of the material they were constantly breaking and giving way under the increased weights imposed upon them4 ,it became necessary to adopt a more reliable material1 and attention was naturally turned to forged or wrought iron4 ,the suggestion once made was promptly responded to by the iron makers4 ,special machinery was designed and constructed1 and very soon wrought-iron rails were manufactured in large quantities4 ,at first they were made very similar in section to the fish-belly cast-iron rails1 but in lengths to extend over three or four sleepers4 ,the increased length gave greater stability to the road1 and permitted an increase of speed4 ,the manifest superiority of the wrought-iron rails led to their universal adoption1 and a great impetus was thus given to their manufacture4 ,improvements were made in the machinery for rolling1 and more care was bestowed in the working of the iron4 ,changes were made in the section of the rails2 the fish-belly form was discarded1 and a double-head type was introduced to give more lateral stiffness4 ,at this period in its history the capabilities of the iron road began to be more fully recognized1 and the supporters of the system foresaw a great future success1 both for the conveyance of passengers as well as goods4 ,hitherto the tramroads or railroads had been used for minerals and merchandize only1 but it was now claimed that on a carefully constructed line1 and with improved locomotives and rolling-stock1 it would be possible to convey passengers more conveniently and rapidly than by any other method4 ,illustration3 ,fig4 #bcf1 #bcg1 #bch1 #bci1 #bdj1 #bda1 #bdb1 #bdc1 #bdd1 #bde1 #bdf1 #bdg1 #bdh1 #bdi1 #bej1 #bea1 #beb1 #bec1 #bed1 #bee1 #bef1 #beg1 #beh ,inventive minds were at work to accomplish so desirable an object1 and public enterprise was forthcoming to provide funds for the purpose4 ,the successful working of the first passenger line formed the dawn of a new era in travelling1 and similar lines were soon projected for other places4 ,the wrought-iron rails in use at this time were generally of a double head form1 and rarely exceeded #ab or #ae feet in length4 ,they were held by wooden pegs in cast-iron chairs1 which were secured to timber cross-sleepers or stone blocks1 as shown in ,figs4 #ahh #bcd and #bce4 ,they were light in section1 and it is stated that the first rails on the ,liverpool and ,manchester ,railway weighed only #cc lbs4 per yard4 ,the railway system spread rapidly1 and the constantly increasing traffic of all kinds soon necessitated heavier rails4 ,various sections were devised and tried on different lines1 one of the main objects in view being to obtain a steady road for the increasing speeds1 as well as one of durability4 ,some of these sections are shown in ,figs4 #bcf to #beh4 ,sections #bcf to #bdh all required chairs to attach them to the sleepers4 ,the flange rails1 #bdi to #bec1 and bridge rails1 #bed to #bef1 also rail #beg1 were designed to rest direct upon the sleepers without the necessity of chairs2 and the ,barlow rail1 #beh1 with its great width of #aa or #ab inches1 was intended to be used without sleepers of any kind1 the gauge being secured by means of angle iron tie-bars4 ,rails were rolled heavier and longer1 and more care was bestowed on the fastenings2 but1 notwithstanding these improvements1 the rail-joints still continued to be the weak point in the road4 ,even with an extra large joint-chair and stout wooden key1 there was much vertical play at the ends of the rails1 producing objectionable noise and vibration in the running1 and acting detrimentally on all the fastenings4 ,the introduction of fish-plates at the rail-joints1 as shown in ,fig4 #bei1 effected an improvement which cannot be overrated1 as by their adoption such security1 speed1 and smoothness became attainable as were not before possible4 ,with a pair of simple rolled wrought-iron fish-plates1 or splices1 and four bolts--two through the end of each rail--a better1 smoother1 and more effectual joint was obtained than had ever been produced by the heavy cast-iron joint-chairs4 ,the system of fishing1 or splicing1 was at once admitted to be the simplest and most direct method of joining the rails2 and1 although minor detailed improvements have since been made1 the arrangement1 as a principle1 has never been superseded4 ,many miles of fished rails were laid down with a chair1 or support1 placed immediately under the joint1 forming the method termed the supported fish-joint2 but experience proved that this mode of application did not give such a good result as the suspended fish-joint1 and the latter plan has now been adopted on almost all railways4 ,illustration3 ,fig4 #bei1 #bfj1 #bfa1 #bfb1 #bfc1 #bfd1 #bfe1 #bff1 #bfg1 #bfh1 #bfi1 #bgj1 #bga1 #bgb ,the experience obtained year after year in the wear of rails under #aij heavy traffic1 led to continued improvements both in the method of rolling and in the selection of the iron to form the rail-pile2 one description of iron was found more suitable for the head1 or running surface1 and another for the vertical web2 but1 even with the best machinery and most carefully assorted materials1 high-class wrought-iron rails were liable to lamination1 and long thin strips of iron became detached from the upper1 or wearing1 surface4 ,the rail was composed of many layers of iron1 and it was not always possible to ensure that they were all thoroughly welded1 or incorporated together4 ,as early as #ahed a few experimental solid steel rails were laid down on some of the principal railways1 and gave excellent results as to evenness of wear and durability1 but their cost of manufacture rendered their extended use almost prohibitory4 ,compound rails of steel and wrought-iron1 as in ,fig4 #bfj1 were also tried on several railways1 but the practical results were not such as to lead to a very extended adoption4 ,in preparing the pile for a compound rail1 suitable wrought-iron bars were placed to form the lower member or flange1 the web1 and part of the head1 and a slab of steel was placed on the top to form the upper portion of head1 or wearing surface of the rail4 ,it was intended that in the process of rolling these distinct layers were to be incorporated together1 to form the section shown in ,fig4 #bfj4 ,doubtless many good wearing rails were manufactured on this system1 but the inherent difference of the two materials1 steel and iron1 rendered it very difficult to ensure such uniform incorporation as would withstand the constant pounding under heavy1 fast traffic4 ,it was not until some years later that the process of the ,bessemer ,converter was discovered and perfected1 by means of which steel can be produced in large quantities far more rapidly and at much less cost than by any other method hitherto adopted4 ,the introduction of this process for making steel caused a complete revolution in the material for rails4 ,steel which had previously been excluded on account of its cost1 could now be supplied at a moderate price1 and1 from its compact and homogeneous character1 promised a very much longer wearing life than the best wrought-iron rails that had ever been rolled4 ,experience has shown that these promises have been fully verified2 wrought-iron rails are things of the past1 steel rails have taken their place1 and can now be purchased #aia at a less price per ton than the iron rails of twenty years ago4 ,it is interesting to note that out of the many varied sections that have been designed1 some of which are shown in the sketches described1 only two have practically survived--the bullhead rail and the flange rail4 ,the bull-head rail1 ,fig4 #bfa1 has grown out of the original double-head rail1 which had both the top and bottom members made to the same section and weight1 with the object that1 when the upper table had become so much worn as to be unfit for further use1 then the rail could be turned1 and the other table1 or head1 brought into service4 ,experience1 however1 proved that turned rails formed a most uneven and unsatisfactory road1 the long contact with the cast-iron chairs resulted in serious indentations at the rail-seats1 rendering the rails totally unfitted for smooth running4 ,in practice1 therefore1 it has been found better to restrict the running wear to one head only1 and to give increased sectional area to that head1 and1 at the same time to diminish the sectional area of the lower member to a corresponding extent1 but to retain the same width1 so as to obtain a full bearing surface on the cast-iron chair4 ,steel bull-head rails are now adopted on nearly all the principal lines at home1 and on several of the leading lines abroad4 ,the flange rail1 ,fig4 #bfe1 was designed to give a broad1 direct bearing on the sleepers1 and thus avoid the necessity of using chairs4 ,rails of this section have been laid down on many of our lines at home1 and are very largely used on the ,continent1 in the ,united ,states of ,america1 and in our colonies generally4 ,this section is1 also1 nearly always adopted for narrow-gauge railways4 ,having fewer parts1 it makes a cheaper road than the bull-head rail1 but is not considered so strong or suitable for heavy and fast traffic4 ,comparing the two rails shown in ,figs4 #bfa and #bfe1 each having exactly the same size and sectional area in the head1 it will be seen that there is more material in the lower member1 or flange1 of the one rail than there is in the lower member of the other2 the weight per lineal yard being #gi lbs4 for the former and #ge lbs4 for the latter4 ,but this small excess in the weight and cost of the flange rail falls very short of the cost of the cast-iron chairs and wooden keys necessary for the bull-head rail4 ,up to the years #ahgj-ahge1 it was the common practice to make the top1 or wearing surface of the rail1 comparatively round1 as shown on the #aib typical sections1 ,figs4 #bfc and #bfg4 ,the effect of this sharp-curved outline was to limit the first wearing1 or contact surface to a narrow strip along the head of rail1 causing a tendency to groove or form hollows in the treads of the wheel-tyres4 ,as the rail wore down1 the upper surface assumed a much flatter curve1 more closely assimilated to the section of the wheel-tyre1 and giving better results for regular wear under heavy traffic4 ,profiting by this experience1 the rails of the present day are made much flatter on the head than they were formerly1 as will be noted from the sections shown on ,figs4 #bfa1 #bff1 and #bfi1 which represent types of rails now actually in use on some of the principal railways4 ,in designing a rail for any given line1 the section and weight of the rail must necessarily be influenced by the weight of the rolling-stock passing over it1 and the amount of the traffic it has to sustain4 ,the engine1 being the heaviest vehicle in the train1 will give the measure of the greatest weight on one pair of wheels4 ,engines vary considerably on different lines1 ranging from ten tons to eighteen tons or more on one pair of driving-wheels1 according to the description of work to be performed4 ,very often secondary or branch lines1 with comparatively light traffic1 have steep gradients1 necessitating engines as heavy as on a main trunk line2 but the number of trains on the former may not exceed twenty per day1 while on the latter they may amount to one hundred and fifty or two hundred4 ,it is evident that the rail which would last for very many years under the small traffic1 would have a very short life under the frequent traffic4 ,hence the reason why it is found expedient to give a large increase of material in the heads of rails carrying the heavy1 constant train service of many of our main lines4 ,figs4 #bfa1 #bfb1 and #bfc are sections of rails in use on lines having heavy engines and fast trains1 but with a comparatively small daily train service1 and ,figs4 #bfd1 #bff1 #bfg1 and #bfh are sections of rails carrying the heavy1 fast1 and incessant traffic of some of our leading lines4 ,on lines having small traffic1 slow speeds1 easy gradients1 and comparatively light engines1 a reduced section of rail may be adopted2 but in doing so it is well to allow for any probable future development of traffic which might cause the introduction of heavier engines4 ,figs4 #bfi to #bgb show sections of rails varying from #gb to #fj lbs4 per #aic yard1 also a section of a #de-lb4 steel flange-rail1 much used on #c-;foot narrow-gauge railways4 ,valuable and interesting statistics have from time to time been recorded1 with a view to ascertain the average life of a steel rail1 by obtaining the number of million tons of train load which it would sustain before it became worn down to such an extent as to be no longer of service on the line4 ,it will be readily understood that the rate of wear of a steel rail will depend not only on the weight and section of the rail itself1 but on the class of rolling-stock1 and the description of traffic it has to carry4 ,it will also be largely affected by the circumstances of whether the line is on a level or on an incline4 ,the writer has had careful measurement taken of the wear of the steel flange-rail 7,fig4 #bfe71 #gi lbs4 per yard1 and the result shows that with a traffic not exceeding twenty-four goods and passenger trains per day1 one-tenth of an inch was worn off the top of the rail in ten years on the comparatively level portions of the line2 but that the same amount of one-tenth of an inch was worn off in six years by the same traffic1 on the same district of the line1 in places where the gradients varied from #a in #ajj to #a in #gj4 ,the heavy pounding of the engines1 and the working of the brakes tend very materially to shorten the life of the rails on the inclines4 ,as now made1 the steel rails manufactured under the converter process exhibit great similarity in the analysis of their component parts2 at the same time it is well known that a slight preponderance or reduction of one or more of the constituents will result in making the steel hard or soft4 ,the following statement gives the analysis of twelve steel rails1 six of which were classed as hard steel1 and six as soft steel3-- ,,hard ,,steel4--,,analysis ,,of ,,six ,,steel ,,rails ,,which ,,broke ,,either ,,in ,,testing ,,or ,,in ,,line4 ---------------------------------------- --------------------- #a4 #b4 #c4 #d4 #e4 #f4 ---------------------------------------- --------------------- ,carbon #jdg #jea #jef #jdc #jdg #jed ,silicon #jji #jjh #jjh #jji #jjie #jaba ,sulphur #jjf #jjf #jjf #jjf #jjed #jjef ,phosphorus #jjg #jjf #jjf #jjh #jjh #jjeg ,manganese #abc #aaj #jij #abc #aae #abf ,iron #ihjh #ihai #ihcd #ihaa #ihaea #igiff ---------------------------------------- ---------- #ajjjj #ajjjj #ajjjj #ajjjj #ajjjjj #ajjjjj ---------------------------------------- --------------------- ,,soft ,,steel4--,,analysis ,,of ,,six ,,steel ,,rails ,,which ,,stood ,,the ,,test ,,well1 #aid ,,and ,,bent ,,freely ,,without ,,showing ,,any ,,sign ,,of ,,fracture4 ---------------------------------------- ------------------------- #a4 #b4 #c4 #d4 #e4 #f4 ---------------------------------------- ------------------------- ,carbon #jce #jci #jcg #jcd #jce #jbej ,silicon #jjf #jjg #jjg #jjh #jjg #jjfi ,sulphur #jjfb #jjfa #jjfb #jjfa #jjfa #jjdf ,phosphorus #jjfa #jjfa #jjfa #jjfc #jjfb #jjeh ,manganese #jhgj #jhge #jhff #jhfd #jhjj #jfcf ,iron #iheig #ihedc #ihega #iheib #ihfeg #ihida ---------------------------------------- ------------------------- #ajjjjj #ajjjjj #ajjjji #ajjjjj #ajjjjj #ajjjjj ---------------------------------------- ------------------------- ,many rails which have been broken in the line under traffic have been analyzed1 and proved to be hard steel2 while others1 which have been bent into all sorts of shapes1 but not broken during accidents or derailments1 have also been tested1 and proved to be of soft steel4 ,some engineers are advocates for a hard steel rail1 and claim for it greater durability and longer wear2 but even supposing such hard rail should possess a slight superiority over the soft rail1 it is well to consider whether such assumed advantage is not obtained at the risk of incurring greater liability to fracture4 ,it must be borne in mind that a rail1 once placed in the road1 is exposed to all the changes of temperature from heat to frost1 and has frequently to sustain increased strains arising from loose sleepers1 where the gravel or ballast has been disturbed during heavy rains4 ,when writing a specification for steel rails1 it is usual to state the number of tons per square inch in tensile strain which the steel must be able to sustain without fracture1 and also to stipulate that some of the rails will be tested by the falling-weight test4 ,in the latter test a rail is placed1 say at #c feet bearings1 and in a similar position to what it would occupy in the road1 and a weight of eighteen hundredweight1 or one ton or more1 according to section of rail1 is allowed to fall from a height of #i or #aj feet1 on to the rail1 at the centre between the bearings4 ,with three blows from the given height1 the rail must not bend or deflect more than a specified amount4 ,the falling-weight test is1 perhaps1 rather a rough and ready one2 but it is always reassuring to prove that the rails will withstand such a severe ordeal1 as it must be a very exceptional circumstance in the routine of railway working which will produce a blow or shock equal #aie in effect to the falling-weight test4 ,the rails form such an important part of the trackway1 almost the very basis on which the traffic has to depend for its safety1 that1 apart from the question of wear1 no effort should be spared to ensure their thorough soundness and efficiency4 ,in modern practice rails are generally used in lengths varying from #be feet to #cj feet4 ,there is no difficulty in making them longer2 but any excess over the above lengths is found to be inconvenient for transport1 for handling in the line1 and for making the necessary allowance for contraction and expansion at the joints4 ,steel rails are generally marked on the vertical web with the initials of the railway company1 the name of the manufacturer1 and the year in which they are rolled4 ,this is done by cutting out the letters in the last pair of rolls through which the rails have to pass before they are completed1 so that on the rails themselves the letters stand out in raised characters1 thus3 ,g4,n4,r4,i4444444,c4 ,,cammell ,co #ahif4 ,in this manner the rails always carry for reference the name of maker and date4 ,when comparing the relative merits of the flange-rail and bull-head-rail permanent way1 the question of strength and durability must be considered1 as well as that of economy4 ,the flange-rail road has undoubtedly fewer parts and fastenings1 and when the flange is wide1 the sleepers sound1 and the rail securely held down to the sleepers1 the result is a smooth running road4 ,so long as the rail can be maintained in a constant close contact with the wooden sleeper1 the running is almost noiseless1 the jarring on the rails being absorbed or taken off by the timber2 but so soon as a little space or play takes place between the spikes or other fastenings and the upper surface of the flange1 the rail obtains a certain amount of rise1 or lift1 which comes into action upon the passing of every rolling load1 producing unsteadiness in the rail and a clattering noise in the running4 ,a flange of #e inches1 on a sleeper #aj inches wide1 has a bearing surface of #ej square inches 7assuming the sleeper to be square cut1 without any wane on the edges71 and this area of #ej inches is only about half of the bearing surface on the sleeper of an ordinary modern cast-iron chair4 ,main-line locomotives have weights on the driving-wheels varying from #af to #ah and #bj tons4 ,taking #ah tons as representing a common practice for a large express engine1 would give #i tons as the weight imposed on #aif each rail by each driving-wheel ,assuming this weight to be distributed over three sleepers would give a dead weight of #c tons per sleeper1 or #acd lbs4 on every square inch of the #ej square inches of surface1 or rail-bearing area1 on each sleeper1 without taking into account the effect of the blow or percussion from the rolling load4 ,the presence of a loose sleeper throws additional weight on the adjoining sleepers1 and increases the destructive influence on the timber4 ,the constant application of heavy rolling loads on a small bearing area of timber crushes and wears away the timber very rapidly4 ,the small bearing surface of the flange rail expedites the cutting down into the sleeper1 and as the rail beds itself further and further into the wood1 the fastenings must be driven or screwed down to follow the flange4 ,spikes may be driven down1 but the further they go they have a less thickness of timber for a bed1 and therefore a diminished hold4 ,crab bolts are apt to become rusted or ironbound1 so that they cannot be screwed further1 and must then be taken out and replaced with new ones4 ,the narrower the flange1 the more rapidly does the rail-seat cut down to a thickness inconsistent with safety4 ,the sharp edge of the flange-rail has a tendency to cut a channel in the spike1 and it is not at all an unusual occurrence to find strong square shanked dog-spikes1 which have been thus cut into to the extent of a third or even half their thickness4 ,the comparative narrow flange places the spikes at great disadvantage in point of leverage for holding down1 and this weakness is soon made manifest1 particularly on curves1 where additional crab bolts or other devices are rendered necessary to counteract the tendency of the rail to rock and tilt over sideways4 ,when the head of the rail cannot be kept in its proper position1 the gauge becomes widened1 and an irregular sinuous motion takes place in the running of the train4 ,this drawback has been found to be a serious matter where light narrow flange rails have been adopted to carry comparatively heavy1 short wheel-base engines4 ,in some cases wrought-iron sole-plates1 or even cast-iron bracket-chairs1 have been introduced to give more bearing surface on the sleeper and increased support to the rail1 but neither of the two methods give the same simple complete hold to the rail that is obtained by the cast-iron chair for the bull-head rail4 ,on the other hand1 the modern cast-iron chair for the bull-head rail #aig has at least double the bearing surface on the sleeper to that of the flange-rail seat1 so that under the same circumstances of rolling load as above described1 the weight of #acd lbs4 per square inch would be reduced to half1 or #fg lbs4 ,the greater length given to the chair effectually prevents any rocking action on the part of the rail1 and reduces to a minimum any lifting action on the spike4 ,a good fitting chair--especially when keyed on the inside--provides a most effectual support to the rail both vertically and laterally1 and maintains the rail to accurate gauge4 ,by giving proper clearance space at the tops of the chair-jaws1 a bull-head rail can be taken out by simply driving out the wooden keys1 and a new rail inserted without in any way disturbing the chairs or spikes4 ,to change a flange rail necessitates the slackening and removal of a large number of the spikes and crab bolts4 ,as the sleepers under the chair road suffer less from the crushing of the timber1 they have a much longer life in the line1 and remain serviceable until they are incapacitated from decay4 ,this is a very important item in places where timber sleepers are expensive4 ,the steadiness of the chair prolongs the efficiency of the spikes4 ,as the actual wearing portion of the rail is the head1 or wheel contact surface1 a liberal area--consistent with the expected traffic--must be given to that part1 whether for a bull-head rail or a flange rail4 ,by comparing the two sections1 ,figs4 #bgc and #bgd1 the one for an #he-lb4 bull-head rail1 and the other for a #ajj-lb4 flange rail1 it will be seen from the dotted lines that the heads of each rail are almost identical1 the difference of #ae lbs4 being disposed of in the flange of the heavier rail4 ,practically1 therefore1 we have #ae lbs4 per yard extra weight of steel in the rail1 on the one hand1 as against the cast-iron chairs and steadier permanent way on the other4 ,for lines where the traffic is small1 weights light1 speeds low1 and economy of construction imperative1 the flange-rail permanent way will be very suitable4 ,the writer has had long mileages of each description of permanent way under his charge1 both at home and abroad1 for many years1 and the result of his experience has shown that1 although a fairly good road may be made with flange rails1 still1 for constant1 heavy1 fast traffic1 the bull-head rail with cast-iron chairs makes a much stronger1 more durable1 and better permanent way than any flange railroad4 ,illustration3 ,fig4 #bgc1 #bgd ,briefly summarized1 the principal advantages and disadvantages of the #aii two kinds of rails stand as follows3-- ,,advantages4 ,bull-head ,rail4 ,flange ,rail4 ,large bearing surface of chair ,fewness of parts1 and less upon the sleeper1 and greater cost4 stability of the rail4 ,smaller quantity of ballast ,longer life of wooden sleeper4 required to cover up the foot of rail4 ,impossibility of rail tilting over outwards4 ,more lateral stiffness than the bull-head rail4 ,facility for changing a rail without disturbing the fastenings in the sleepers4 ,easier to maintain1 owing to less disturbing strains on the fastenings4 ,a bull-head rail is more readily set or laid to follow line of curve4 ,in most cases the one set of chairs will serve for a second set of rails4 ,perfect straightness of rail3 it is very rare to find a crooked bull-head rail4 ,easier to roll1 and more likely to obtain uniformity of steel4 ,,disadvantages4 ,bull-head ,rail4 ,flange ,rail4 ,bull-head ,rail4 ,the small rail-seat area on sleeper throws great crushing ,greater cost4 weight on the timber4 ,more ballast required to cover ,shorter life of wooden up the rail4 sleepers from the cutting down of rail-seats4 ,less lateral stiffness than the flange rail4 ,the edge of flange cuts the spikes after a few years4 ,the undulation of the rail under trains tends to raise the spikes1 and causes lateral movement in the rails4 ,more difficult to maintain1 in consequence of greater tendency of the fastenings to work loose4 ,difficulty in getting flange rails straightened laterally4 ,more difficult to set to follow regular line of curves4 ,more difficult to roll1 and less likely to obtain uniformity of steel4 ,tramway ,rails4--,tramways on streets or public roads are now universally recognized as important branches of the railway principle4 ,their smoothness of movement1 increased accommodation1 and many other advantages as compared with the old road omnibus1 render it no longer necessary to call for special advocacy when there is a possibility of their introduction4 ,they occupy a position so thoroughly appreciated #bjj by the public that any check on their reasonable use or extension would be considered as detrimental to the interests of the travelling community4 ,as a rule1 these tramways are laid down on streets or roads previously constructed for the ordinary road traffic1 where all the preliminary work of earth filling1 bridges1 drainage1 etc41 has already been accomplished1 and there only remains the selection and laying down of the rails or permanent way over which the tram-cars will have to run4 ,the description and weight of permanent way to be adopted will depend largely upon the weight of the cars to be used and the system of motive-power decided upon for the haulage--whether horses1 steam1 cable1 or electricity4 ,as the portion of the streets or public roads along which the tramway has to be laid will1 in all probability1 have to be occupied and traversed by all kinds of vehicles besides the tram-cars1 it is absolutely necessary that the permanent way for the tramway should be of such description as to require the least possible amount of adjustment of fastenings or opening out of the roadway for repairs4 ,where the entire width of the street1 including the space between the tram-rails1 is paved with stone setts1 the opening out of even a short length for repairs is tedious and costly1 and causes considerable obstruction to the street traffic4 ,it is most important1 therefore1 that the rail and its fastenings should not only be strong enough for its own tram service and the carts and drays which will pass over and across the track in all directions1 but it must possess the minimum necessity for disturbance4 ,figs4 #bge to #bgi are sketches of a few of the many types which have been brought into use in various places4 ,where the public roads are wide1 and a space can be set apart at the side for the special use of the tramway1 the arrangement shown in ,fig4 #bge will be simple and efficient4 ,it is very similar to an ordinary railway permanent way with the ballast filled in flush with the top of the rails4 ,the rails are shown as flange or flat-bottom rails1 fished together at the joints1 and properly secured to transverse sleepers of wood1 iron1 or steel4 ,the space between and outside the rails is filled in with small-sized broken stone ballast or good clean gravel1 and forms an even surface1 over which animals or cattle may pass without risk of being thrown down4 ,illustration3 ,fig4 #bge1 #bgf1 #bgg1 #bgh1 #bgi ,fig4 #bgf represents a system which was laid down extensively1 especially #bjb for horse tramways1 but not proving efficient1 has been superseded by other types of a stronger and more durable description4 ,the rail was rolled with a continuous groove to provide clearance for the flanges of the car-wheels1 and the sides of the rail were turned down so as to fit over the longitudinal timber sleeper1 to which the rail was secured by staple-dogs1 as shown4 ,cast-iron chairs1 spiked on to wooden cross-sleepers1 held the longitudinal sleepers in position4 ,the wooden sleepers were favourable for smooth running1 but the section of the rail1 practically a light channel-iron laid on the flat1 was most unsuitable for carrying weight or for making a proper joint4 ,experience proved this road to be very difficult to maintain in good order for easy traction4 ,the staple-dogs worked loose after a little time1 and the rail1 having scarcely any vertical stiffness1 rose and fell during the passage of every car-wheel1 resulting in most uneven joints and a clattering roadway4 ,with the view to obtain a stronger and more permanent support for the rail than the longitudinal timber sleeper last described1 various forms of cast-iron chairs were devised4 ,fig4 #bgg represents one of these patterns4 ,the rail1 which is of ,t-section with a continuous wheel-flange groove1 is secured to the cast-iron chair by the cross-pin1 as shown4 ,although this cross-pin may in time work a little loose1 it cannot work out1 being kept in position by the paving-setts on each side4 ,the cast-iron chairs are placed at convenient distances1 and being set in a bed of concrete1 do not require cross-sleepers or tie-bars4 ,this type makes a strong road1 but the rail-joints cannot be made so even or efficient as with the more modern form of rail4 ,rail manufacturers are now able to roll a section of rail combining the vertical stiffness of the ordinary flange1 or flat-bottom1 rail with the running-head and continuous wheel-flange groove1 considered the most suitable for heavy tramway traffic4 ,the introduction of this section of rail has contributed greatly to the increased efficiency and durability of the permanent way for street traffic2 and as the ends of the rails can be secured by ordinary fish-plates1 there is the great acquisition of even joints and increased smoothness in the running of the tramcars4 ,this rail can be rolled of various weights to suit the rolling loads4 ,on some tram-lines a moderately heavy section has been adopted1 and secured to transverse sleepers of rolled iron or steel laid on a bed of concrete4 ,on others similar rolled metal sleepers have been used1 but laid longitudinally4 ,for some descriptions #bjc of traffic a much heavier section of rail has been used1 having a base sufficiently wide to provide ample bearing on a bed of concrete without the intervention of either transverse or longitudinal sleepers4 ,fig4 #bgh is a sketch of the modern rail as laid down on a rolled steel transverse sleeper1 the rail being held in position either by turned-up clips1 wedges1 bolts1 or any of the devices in use for similar duty in the rolled-steel sleepers for ordinary railway permanent way4 ,fig4 #bgi shows a modern rail of a heavier section1 with a wide flange resting direct on a continuous bed of concrete4 ,the gauge is maintained by bar-iron tie-bars placed vertically so as to fit in between the courses of the paving-setts1 the ends being forged and screwed to pass through holes in the vertical web of rail1 and secured in position by nuts4 ,both in this1 and in type ,fig4 #bgh1 ordinary fish-plates are adopted at the rail-joints1 as indicated by dotted lines4 ,in the last two examples above described all the materials are of the most durable description1 and the least liable to wear or decay1 but it will be necessary to guard against making the fastenings and the bars too light for the duty they have to perform4 ,there should be ample material in the head of the rail to allow of a fair wearing down1 and the continuous flange groove should be sufficiently deep to meet this wearing away without causing the wheel-flanges to strike the bottom of the groove4 ,illustration3 ,fig4 #bhj1 #bha1 #bhb1 #bhc1 #bhd1 #bhe1 #bhf1 #bhg1 #bhh1 #bhi1 #bij1 #bia ,fish-plates4--,in the first examples of the newly invented wrought-iron fish-plates they were made to the depth to fit in between the upper and lower tables of the rail1 as shown in ,fig4 #bhj1 a small space or clearance being left between the inner sides and the vertical web of the rail4 ,ordinary nuts and bolts were used in most cases1 but in some instances one of the fish-plates was tapped1 as in ,fig4 #bha1 forming one long continuous nut1 and in others both fish-plates were tapped1 as in ,fig4 #bhb1 and right and left handed bolts were used4 ,neither of the two arrangements of tapped fish-plates proved sufficiently successful as to lead to their general adoption4 ,when the bolts became rusted in1 or iron-bound1 it was found to be almost impossible to remove them without permanently damaging the fish-plates4 ,with the four right and left handed bolts the operation of tightening1 or removing1 the fish-plates was very tedious1 as each bolt had to be turned a very little at a time1 one after the other4 #bje ,independent bolts and nuts1 either of iron or steel1 are now universally used2 plain holes1 with sufficient allowance for work and expansion1 being punched or drilled in the rails and fish-plates4 ,for many years the depth of the fish-plates continued to be made the same as the space between the upper and lower members of the rail1 as shown in ,fig4 #bhj2 but with the heavier loads and higher speeds of our modern railway working it has been found necessary to strengthen the joints by providing deeper or stiffer fish-plates1 as shown in ,figs4 #bhc1 #bhd1 and #bhe4 ,for bull-head rails the fish-plates have been brought down underneath the lower table1 and in some cases extended down sufficiently far to admit of a second set of fish-bolts under the rail4 ,for flange rails some fish-plates are used simply of the form of angle irons1 and others have the angle portion carried out beyond the end of the flange1 or foot of rail1 and then turned down vertically to a depth of an inch or more below the rail4 ,the latter makes a very strong fish-plate4 ,fish-plates1 like rails1 are now almost universally made of steel4 ,the efficiency and durability of a fish-plate depends materially upon its angle of contact with the under side of the head of the rail1 and the extent of its contact surface4 ,it would be an error to suppose there is little or no wearing away in fish-plates1 as in reality there is very considerable wear1 and especially in rails of lighter section4 ,if the under side of the head of rail has a curved outline1 as in the rail in ,fig4 #bhg1 there will be some difficulty in ensuring a perfect fit in the fish-plates2 the curve of the one may not quite correspond to the curve of the other1 and the contact surface will be very small4 ,it is better to make these contact surfaces in straight lines1 and to a wide angle rather than to an acute angle4 ,in ,fig4 #bhh the under side of head and corresponding top of fish-plates are set at an acute angle1 and fish-plates to this pattern will soon wear up to the vertical web of rail1 and cause a loose noisy joint4 ,in ,fig4 #bhd1 showing a different type of rail1 the contact surfaces are set at a very much wider angle1 and will allow much more wear before the fish-plates can work close up to the web of the rail4 ,when once the fish-plates are close up to the web1 the best and #bjf tightest bolts cannot prevent the vertical play in the ends of the rails4 ,a hammering sound will announce each successive drop of the wheels from one rail to the other1 more distinctly1 perhaps1 at slow speeds than when travelling quickly1 but existing equally under both conditions4 ,the unpleasant jarring sensation is annoying to the passengers1 and has a straining1 loosening effect on all the bolts and fastenings4 ,unless the fish-plates have a thorough continuous bearing against the upper and lower shoulders of both the rails1 it will be impossible to obtain a smooth even joint4 ,a road may have good rails1 good chairs1 and good sleepers1 but if the fish-plates are worn and loose the entire permanent way may be pronounced faulty1 and all on account of a minor defect which can be easily remedied4 ,with strong1 properly fitting fish-plates1 the position of the joints should be imperceptible when passing over them in a train4 ,the writer has had many miles of line where the fish-plates have worn hard up to the rail web4 ,in cases where the rails were good1 with the prospect of a long life1 new fish-plates of suitable section have been provided4 ,in others1 thin wrought-iron plate liners1 #a_/af or #a_/ab of an inch thick1 have been inserted1 as in ,fig4 #bia1 so as to bring the plates well out from the web1 and allow the fish-bolts and fish-plates to exercise the free gripping action which is absolutely necessary to prevent the vertical rising and falling of the rail-ends during the passage of a rolling load4 ,fish-plate liners of the above description have given excellent results1 and have restored the efficiency of the fish-plates for several years4 ,chairs4--,all rails which partake of the double head section1 or have a base not wider than the head1 require supports or carriers to attach them to the sleepers1 and to secure them in their proper upright position4 ,in the days of the original edge rails1 at the commencement of the railway era1 these supports were very appropriately termed chairs1 and this name has now been adopted in all parts of the world4 ,cast-iron is the most suitable material for railways chairs1 being much cheaper in cost and less liable to loss or deterioration from rust than wrought-iron4 ,cast-iron chairs can be formed to suit any section of rail1 and from the nature of the material they cannot be bent or twisted out of shape so as to interfere with the gauge or cant4 ,they may break during an accident or derailment1 but the fracture can be detected at once1 and the broken #bjg chair quickly replaced4 ,the chair performs the very important duty of distributing the weight of the rolling load on the upper surface of the sleeper4 ,if the under side or base of the chair is small1 and the rolling load large1 the chair will very rapidly wear or imbed itself into the wood of the sleeper1 shortening the life of the latter in a very palpable manner4 ,the short narrow chair naturally gives less stability than the larger and broader chair4 ,the chair shown in ,fig4 #bib1 which was much used for #ge lb4 rails some twenty years ago1 has much less base area and stability than the chair shown in ,fig4 #bic1 adopted for rails of a similar weight in the present day4 ,the former had a bearing surface on the sleeper of only #ec square inches1 as compared with #hi square inches in the latter4 ,the base area of the chair must be in proportion to the weight it has to carry and distribute1 and it would be false economy to stint the surface area of one of the details which influences so materially the stability and durability of the permanent way4 ,as will be seen in ,figs4 #bid1 #bie1 and #bif1 the chairs at present used for #hj1 #he1 and #ij lb4 rails have a much larger bearing surface than the chair shown in ,fig4 #bib4 ,with the wider chair1 a much longer and better seat can be given to the under table of rail1 and a greater length of jaw for holding the wooden key4 ,the longer the rail-seat the steadier the rail and the smoother the running4 ,the keys are generally made of hard wood1 sometimes compressed by a special process1 cut slightly taper1 or wedge1 shape1 and driven in between the jaw of the chair and the vertical web of the rail4 ,on some railways the key is placed outside the rail1 as in ,fig4 #big1 and on others inside the rail1 as in ,fig4 #bih4 ,the latter method possesses many advantages over the former4 ,the outer jaw of the chair can be brought well up to the under side of head of rail1 giving the rail more lateral support and better means of preserving the correct cant2 and1 as in this chair the outer jaw permanently fixes the gauge1 the working out of one or more of the keys does not leave the rail exposed to be forced outwards and widen the gauge1 as in the case with dropped keys in outside keying4 ,another and very important advantage of inside keying is that platelayers1 when inspecting the road by walking between the rails1 can readily examine the keys on both sides4 ,illustration3 ,fig4 #bib1 #bic1 #bid1 #bie1 #bif1 #big1 #bih1 #bii1 #cjj1 #cja1 #cjb1 #cjc1 #cjd1 #cje1 #cjf ,chairs have been made1 as in ,fig4 #bii1 with a recess in the rail-seat1 #bji to hold a piece of prepared wood1 or other suitable semi-elastic material1 the object being to provide a rest1 or cushion1 softer and more yielding than the cast-iron4 ,the idea looks well in theory1 but in practice the pounding on the rail compresses or crushes the wood lower and lower into the recess1 slackened keys have to be tightened1 and when the wood has been worn or crushed away down to the level of the stop ribs1 ,a1 ,a1 the under side of rail has no longer any seat1 or rest1 beyond the two narrow ribs of cast-iron4 ,these afford such a very limited support that the rail becomes notched1 and produces a very rough clattering road4 ,it is a very simple matter to take out an old key and put in a new one1 but to replace a wooden cushion in a chair recess involves the entire removal of either the rail or the chair4 ,chairs with wooden cushions have not been adopted to any great extent1 the tendency of modern practice being to reduce as far as possible the number of parts of the permanent way1 and to provide those parts with ample bearing or contact surfaces4 ,although the general practice has been to cast the chairs in one piece1 chairs have been made in two pieces1 as in ,fig4 #cjj1 fastened together and to the rail by a bolt passing through the latter1 the castings being secured to the sleeper with spikes4 ,at first sight this pattern of chair appeared to possess some features in its favour4 ,the castings were simple1 keys were dispensed with altogether1 and the under side of rail was not in contact with the cast-iron4 ,a short experience1 however1 proved that the drawbacks far outweighed the apparent advantages4 ,holes for the through-bolts had to be punched at fixed distances in the rails1 and although this could be readily done at the works1 for the general use on the line it was necessary to resort to the tedious process of drilling by hand for a large number of holes on curves1 and for rails cut to form closers4 ,sleepers4--,wood possesses so many suitable qualities that we can readily understand why it was early selected as the proper material for sleepers4 ,it can be cut to any size and shape1 holes can be bored1 spikes can be driven1 and bolts can be screwed into it without any difficulty and without causing injury to the timber1 while the semi-elastic nature of wood absorbs the vibration of the rails and fastenings1 and provides a sound-deadening seat so conducive to smooth running4 ,its only drawback is that it is perishable from wear and #baj decay4 ,were it not for this defect1 railway sleepers of wood might be considered as simply perfect4 ,with a view to greater permanency and durability1 stone sleepers were tried4 ,these consisted of square blocks of good hard stone1 measuring about #b feet wide each way and #ab inches thick4 ,holes were cut in the stone1 and plugs of hard wood inserted4 ,the cast-iron chairs were then placed on the top of the blocks1 and the iron spikes driven through the chair-holes into the wooden plugs4 ,the elements of permanency were there certainly1 but a rougher road it would be impossible to conceive4 ,the stone was solid and unyielding1 there was a total absence of softness and elasticity1 and the harsh noisy effect produced when running over the stone-block road very soon became intolerable4 ,stone-block sleepers were found to be a failure1 and were all removed4 ,on some of our old lines1 numbers of them1 with the chair marks plainly visible1 may be still seen in loading banks1 buildings1 sea walls1 and other works for which they were never originally intended1 but for which their size and weight render them very appropriate4 ,wooden sleepers are used in two forms1 transverse and longitudinal4 ,in the former1 as in ,fig4 #cja1 the sleepers not only carry the rails1 but also preserve the gauge2 in the latter as in ,fig4 #cjb1 the longitudinal sleepers only support the rails1 additional timbers and strong fastenings being necessary to maintain the gauge4 ,longitudinal sleepers have been used to a large extent for bridge rails1 it being supposed that with the broad continuous sleeper a lighter and shallower rail could be adopted1 which would be equally efficient as a heavier rail on cross-sleepers4 ,excellent running roads have been made with longitudinal sleepers1 notwithstanding the difficulty of making a good bridge-rail joint2 but it is well to bear in mind that almost all the lines which originally adopted this form of permanent way have since reverted to the ordinary cross-sleeper road4 ,the longitudinal sleeper road is an expensive road to lay down and maintain4 ,the main pieces are of large scantling1 must be of good quality of timber1 and are consequently costly4 ,the cross-pieces1 or transomes1 must be carefully fitted and secured with heavy ironwork4 ,where there is much traffic1 the removal and renewal of one of the long timbers is much more difficult than the renewal of several ordinary #baa cross-sleepers4 ,again1 decay may take place on only one portion of a main timber1 but there is no alternative but to remove the entire piece4 ,for gauges varying from #d feet #h inches to #e feet #c inches1 cross-sleepers are cut to the length of #h feet #aa inches1 and are generally rectangular in section1 as in ,fig4 #cjc1 measuring #aj inches in width by #e inches in thickness4 ,on some of the lighter railways with small traffic1 sleepers are often used only #i inches wide by #d inches thick1 while occasionally on some lines1 and in places where there is exceptionally heavy and constant traffic1 sleepers #ab inches wide by #f inches thick are adopted4 ,half-round sleepers1 as in ,fig4 #cjd1 are used on many lines because they are cheaper4 ,in some cases the flat side of the sleeper is placed downwards1 and the rail or chair is fastened into an adzed seat cut in the round side2 and in the others the round side is placed downwards1 and the flat side of the sleeper carries the rail or chair4 ,triangular sleepers1 as in ,fig4 #cje1 have also been used1 made by cutting the blocks diagonally1 so as to obtain the greatest possible width4 ,they were laid with the flat side upwards1 and the apex downwards4 ,they were difficult to keep packed1 and have not been adopted to any great extent4 ,with the exception of a limited number of larch and fir sleepers grown in the country1 most of the sleepers for our home railways are imported from the ,baltic4 ,they are brought over in logs1 or blocks1 each #h feet #aa inches long1 some square and others circular in section1 and when sawn down the middle1 each block forms two sleepers4 ,the preservation of timber from decay is a subject that very early occupied the attention of engineers and all those interested in railways4 ,a railway sleeper is particularly exposed to deterioration the lower portion being surrounded with moist ballast1 whilst the top portion is more or less uncovered--two different conditions in the same piece of timber4 ,several processes have been tried1 such as ,kyanizing1 ,burnetizing1 ,boucherizing1 etc41 but the system which has given the best results1 and is now almost universally adopted1 is that known as creosoting4 ,this method consists of forcing liquid creosote1 under considerable pressure1 into sleepers or railway timbers which have been prepared or dried by ordinary natural seasoning or by special artificial means4 ,creosote is a dark1 oily liquid1 distilled #bab from coal tar1 varying in its composition according to the quality of the coal from which it is obtained1 and ranging in its specific gravity from #aajh to #ajbh4 ,creosote oils of light specific gravity were at one time in favour1 but experience proved that1 to some extent1 the light oils were volatile and also soluble in water1 and that heavy rains washed out the constituents which were essential for the preservation of the timber4 ,on the other hand1 by heating the heavy oils and using high pressure the napthaline which is dissolved only by the heat1 is forced into the wood1 fills the pores1 and solidifies4 ,creosote is obtainable in large quantities1 at prices varying from twopence to fourpence per gallon1 according to the demand and cost of production4 ,newly delivered sleepers or railway timber contain so much sap or water that it is impossible to force a sufficient quantity of creosote into them until they are properly seasoned or dried4 ,the seasoning is generally arranged by sawing each block into two sleepers1 and then stacking the sleepers on edge in tiers1 leaving a space of four or five inches between each of them for a proper circulation of air4 ,the sleepers should then be left for nine to twelve months to season1 although more may be necessary in some cases if the blocks were particularly wet at the time they were sawn4 ,when ready for the process the sleepers are placed in the creosoting cylinder1 which is generally about #fj feet long by #f feet in diameter with semi-spherical ends4 ,one of the ends is fitted with strong hinges and fastenings1 and forms the doorway4 ,the sleepers are packed carefully inside1 and the doorway made tight4 ,the machinery is then set to work to exhaust the air from the cylinder and allow the creosote to flow in amongst the sleepers4 ,when the cylinder is full the force-pumps are started to force in more creosote up to the pressure prearranged and regulated by the safety-valve1 in some cases #ajj1 #aaj1 or #abj lbs4 per square inch4 ,the creosote should be heated to #aab or #abj ,fah41 to dissolve the napthaline and reduce all the component parts to a thoroughly fluid condition4 ,the success of creosoting depends almost entirely upon the effectual seasoning of the timber4 ,only a very small quantity of creosote can be forced into wet or unseasoned sleepers1 even with the best machinery and exceptionally high pressures1 while a thoroughly dry sleeper will #bac readily absorb from #b to #c gallons4 ,more could be forced into the dry sleeper if necessary1 but a little consideration will show there would be no advantage in doing so4 ,in railway sleepers there are two elements of destruction at work--one the decay of the timber1 and the other abrasion or wearing away of the wood itself from the constant pounding of the passing loads4 ,more particularly does this wearing-away take place with the flange1 or bridge1 rails1 their distributed bearing surface on the sleeper being less than the cast-iron chairs4 ,a thoroughly well-creosoted #e-;inch sleeper laid originally with a thickness of #d- inches in the centre of rail-seat1 as in ,fig4 #cjf1 will wear down #a inches1 the timber remaining quite sound4 ,the writer has had to take out thousands of sleepers where the seats of the flange1 or bridge1 rails had been pounded or worn down so deep into the wood as to leave too small a thickness of timber to carry the rail with safety4 ,these sleepers had to be taken out of the road1 not on account of decay1 but because they were actually worn down too thin to be of service4 ,they had done their work well for a long series of years1 and were perfectly sound when taken out4 ,no increased quantity of creosote would have made them last longer1 and any increased quantity of creosote would have been waste4 ,two and three quarter gallons of creosote is a very good and suitable quantity for a #aj inch by #e inch rectangular sleeper1 but not more than half this quantity can be forced in if the sleeper is wet or unseasoned4 ,sleeper-blocks are generally cut from the upper part of the tree1 and do not therefore consist of the best portion of the timber1 yet sleepers made from the soft1 coarse-grained ,baltic wood1 properly creosoted1 will last from twelve to eighteen years in the line in this country1 while uncreosoted they would perish from decay in six or seven4 ,the benefit is great when1 by adding from eightpence to a shilling for the cost of creosoting1 the life of the sleeper may be doubled or trebled4 ,of course1 there are countries1 like the far west of ,america1 where the lines pass through vast forests1 and where sleepers may be had for the mere cost of cutting4 ,creosoting in those places would be out of the question1 and would cost four or five times the value of the plain sleeper4 ,it is found1 also1 that in tropical countries and in dry climates at high altitudes creosote loses its #bad efficiency1 and in those districts the best creosoted soft-wood sleeper perishes from a species of dry rot in three or four years4 ,where wood sleepers have to be used in tropical climates it is better to obtain them from the timber of the district1 although in many cases suitable trees are difficult to procure and the cost of land transport is very heavy4 ,the soft cushion-like effect of a sound1 properly packed wooden sleeper contributes so largely to form an easy1 smooth-running road1 that so long as they can be obtained at a moderate cost1 and are fairly durable1 wooden sleepers will always be preferred to those of any other material4 ,the great question will be the supply4 ,creosoting and other wood-preserving processes have done much to prolong the life of sleepers1 but the rapidly increasing extent of mileage throughout the world1 together with the enormous number of sleepers required annually for maintenance or renewals1 must before very long severely tax the powers of supply4 ,in the great timber-producing territories the axe is often heard1 but the planter is rarely seen4 ,vast forests are cleared away1 and their sites transformed into busy towns or cultivated lands2 and unless some great change takes place1 and planting be carried out on a large scale1 some other material will have to be adopted for this important item of our permanent way4 ,appearances would indicate that at no very distant date iron or steel will take a conspicuous part in the formation of future railway sleepers4 ,more than thirty years ago several descriptions of cast-iron sleepers were introduced into notice and tried on some of our leading home railways4 ,cast-iron was at that time considered more suitable for the purpose than wrought iron1 as it was very much less costly in price1 and could be readily worked into any desired form or size1 with the advantage that the castings would all be duplicates of one another4 ,illustration3 ,fig4 #cjg1 #cjh1 #cji1 #caj1 #caa1 #cab1 #cac ,figs4 #cjg to #cac show some of the types that were designed and laid down in the road4 ,in ,fig4 #cjg the sleeper and chairs were all cast together in one piece2 the rail was held in its place by wooden keys1 and the gauge of the line was maintained by transverse wrought-iron tie-bars4 ,the sketch represents one of the sleepers used at the rail-joints1 and has three chairs1 the larger one in the centre being for the support of the ends of the rails4 ,this arrangement was the #baf same as was then in use on the ordinary wood-sleeper road1 where an extra large chair was placed at the rail-joints1 and was the most approved method for many years before fish-plates were introduced4 ,the intermediate sleepers were shorter1 and had only two chairs4 ,fig4 #cjh represents a long1 flat1 cast-iron sleeper made in two halves1 bolted together just below the under side of rail at each of the three chair-seats4 ,the rail was gripped and held in position without the use of wooden keys4 ,this being a joint sleeper1 three chairs were used1 as in ,fig4 #cjg4 ,only two chairs were used on the intermediate sleepers4 ,figs4 #cji and #caj are somewhat similar1 but the circular one is higher and more cup-shaped than the other of oval form4 ,the oval pattern has two small recesses for holding two small hard-wood cushions4 ,the circular holes shown in the sides of the sleepers were intended to facilitate the packing1 or tamping1 of the light sandy ballast4 ,fig4 #caa represents a rectangular cast-iron sleeper1 as used for the flange rail4 ,the rail rests on cast-iron cross-ribs1 bevelled to give the proper cant1 and is held in position by the tie-bar bolt and clip-piece1 as shown4 ,the small projecting lug1 formed on the under side of sleeper1 fits into a corresponding notch in the tie-bar1 and keeps the sleepers to gauge4 ,the tie-bar passes through the loop end of the same bolt which secures the rail1 and is held up tight against the under side of sleeper4 ,figs4 #cab and #cac1 both the same in principle1 possessed features which appeared to give great promise4 ,they were simple in construction2 the rail was kept well down1 and did not come in contact with the cast-iron at any point4 ,the long wooden wedges1 which fitted into the rough or serrated sides of the casting1 acted as a cushion to the rail1 and were intended to sink deeper into the recess as the super-imposed weight increased1 or the wood became thinner from shrinkage4 ,in practice1 however1 it was found that these sleepers were not the success that was anticipated4 ,it was soon observed that sand and fine particles of gravel from the ballast worked their way into the lower part of the recess1 and became so compact as to prevent the wooden wedges working further down to increase their grip on the rail4 ,even when the recess was kept free and clear of sand1 the enormous pressure exerted by the wooden wedges broke the iron at ,a1 although an extra thickness was given to that #bag part of the section4 ,the cast-iron was exposed to the greatest strain at the point where it was the least capable of offering resistance4 ,much ingenuity was displayed in many of the patterns brought forward1 but in dealing with a hard unyielding material like cast-iron1 it is difficult1 if not impossible1 to impart any soft1 elastic effect2 and the different systems of cast-iron sleepers failed to become popular on our home railways1 on account of the noise and vibration when trains passed over them4 ,another objection was the great multiplicity of parts required in many of the types1 and the constant and severe strain produced on the fastenings on the passing of every wheel4 ,the bolts might be made tight at first1 but the incessant shaking would work them loose1 the threads became stripped1 and the rails ceased to be held in a proper and secure position4 ,the cast-iron sleeper road was considered unsuitable for the heavy and fast traffic of our home lines1 and was ultimately all taken up and replaced with wooden transverse sleepers4 ,at the same time1 there is no doubt that cast-iron sleepers have been of great value in ,india and tropical climates1 where timber sleepers were not only scarce1 but perish very rapidly4 ,very large numbers of them have been laid down abroad of patterns very similar to those shown in ,figs4 #cji1 #caj1 and #caa1 and have done good service for many years4 ,they are not affected by rain or heat1 but1 unfortunately1 being castings1 are liable to considerable annual loss from breakage4 ,improvements in plate-rolling machinery1 and in appliances for bending and stamping wrought-iron1 have materially assisted in developing the introduction of wrought-iron and steel sleepers4 ,cast-iron and wrought-iron are1 in the abstract1 hard and non-elastic as compared with wood2 but whereas cast-iron can only be made into fixed1 unyielding shapes1 wrought-iron and steel can be worked into forms that possess a certain spring-like effect1 which not only enables them almost entirely to resist fracture1 but also imparts a measure of elasticity to the permanent way4 ,the simplest form of wrought-iron sleeper would be a plain1 flat plate1 to which the chair1 or rail-bracket1 would be attached2 but as this form would have bearing surface only1 without any lateral hold on the ballast to keep the rails to line1 it could not be adopted4 ,during the last few years very many types of wrought-iron and steel #bah sleepers have been introduced1 and nearly all of them of the transverse-sleeper pattern1 formed out of rolled plates2 the sides1 and in some cases the ends also1 are bent1 or turned down to obtain a hold in the ballast4 ,where bull-head or double-head rails are used1 cast-iron chairs1 or wrought-iron bracket chairs1 are bolted1 or otherwise secured to the upper surface of the sleeper1 a layer of felt1 tarred paper1 or other soft material being placed between the two metal surfaces4 ,where flange rails are used1 they are fastened to the sleepers either by bolts1 clamps1 or clips raised up out of the iron sleeper1 and bent over to hold tightening keys4 ,rolled transverse sleepers can readily be bent1 or set in the centre to give the proper cant at the rail-seat2 and in some types the sleepers are pressed in the machines1 so as to be narrower towards the centre1 and with a deeper turnover1 to obtain increased stiffness4 ,in ,figs4 #cad to #cai are shown some of the patterns which have been brought out1 laid down in actual practice1 and in use at the present time4 ,from the fact that wrought-iron and steel sleepers have been laid down in so many places where cast-iron sleepers were discarded or refused a trial1 it is evident that the former are considered to have qualities which the latter did not possess4 ,rolled iron or steel sleepers are coming more and more into use1 especially on foreign or colonial railways4 ,so long1 however1 as good1 well-creosoted timber sleepers can be obtained for our home railways at prices from #cs4 #h;d4 to #ds4 #h;d4 each1 and last from fourteen to twenty years1 there is little probability that they will be supplanted by iron sleepers at double the cost4 ,but abroad the circumstances of cost and durability are different1 and there the rolled iron or steel sleepers1 which will outlive two or three sets of wooden ones1 must claim advantages which cannot be overlooked4 ,the difficulty will be in the fastenings1 the mode of attaching the rails to the sleepers4 ,the constant hammering of metal upon metal1 resulting from the vibrations of every passing load1 will quickly wear or loosen bolts1 rivets1 or wedges1 and the fastenings which will prove the most efficient will be those that are the simplest and most readily adjusted4 ,fastenings4--,figs4 #cbj to #cce illustrate some types of the principal fastenings used in connection with the chair road1 and with flat-bottomed or flange rails4 ,illustration3 ,fig4 #cad1 #cae1 #caf1 #cag1 #cah1 #cai ,the fish-bolts1 ,figs4 #cbj and #cba1 are of a form which is in very #bbj general use both for steel bull-head rails and steel flange rails4 ,by making the neck square or pear-shaped1 to fit into corresponding hole in the fish-plate1 the bolt is prevented from turning round when the wrench or spanner is applied to tighten the nut4 ,a channel or groove is sometimes rolled on the outside of fish-plate to grip bolts made with square heads4 ,some engineers adopt two nuts1 others prefer one nut of extra depth4 ,washers are used in some cases1 but are not universal4 ,with a deep rail it is preferable to place the nuts inside1 so that the platelayer inspecting his length can see both rows of nuts as he walks along between the rails4 ,with shallow rails the nuts must be placed outside and the cup-heads inside1 to give ample clearance to the wheel-flanges4 ,fish-bolts are subject to very severe work4 ,heavy rolling loads passing over the rail-joints--frequently at very high speeds--bring into play all the gripping power of the fish-bolts to maintain a firm support of the fish-plates to ends of rails1 and the constant action of pressure and release produces a loosening or unscrewing motion in the bolts which is very difficult to counteract4 ,loose fish-bolts cause clattering joints and uneven road1 and unless promptly remedied1 the screw threads are soon destroyed and bolts rendered useless4 ,many devices have been invented to prevent or check this loosening of the bolts2 one of the methods1 and a very simple one1 consists of a plain steel bolt with a steel lock-nut1 made as shown in ,fig4 #cbb4 ,as will be seen from the section1 one-half of the nut is tapped of the same size as the bolt1 and the remainder with deep-locking threads4 ,the first half of the nut is readily screwed on to the bolt1 but considerable force must be exerted to screw on the portion having the deep-locking threads2 practically the second half of the nut has to cut a new or deeper thread for itself when screwing round the bolt4 ,illustration3 ,fig4 #cbj1 #cba1 #cbb1 #cbc1 #cbd1 #cbe1 #cbf1 #cbg1 #cbh1 #cbi1 #ccj1 #cca1 #ccb1 #ccc1 #ccd1 #cce ,the slits or grooves at the angles of the nuts form four distinct cutting edges for shaping the deep threads4 ,as the upper part of the lock-nut is divided by the grooves into four separate or detached segments1 these segments will be forced slightly open or outwards during the action of cutting the deep thread on the bolt1 and from their natural tendency to return to their original position they must exercise a strong gripping power on the bolt4 ,this combined operation of cutting the deep threads and of forcing open the upper or detached #bbb segments1 give an enormous holding and retaining power to the lock-nut1 and enables it to withstand the train vibrations for a very long time without any perceptible slackening4 ,in case of line repairs the nut can be readily unscrewed1 and taken off the bolt4 ,round iron spikes1 as in ,figs4 #cbc and #cbd1 and round wooden trenails1 as in ,fig4 #cbe1 are both used for fastening cast-iron chairs to the sleepers4 ,the spikes are made with a slightly taper neck1 of size rather less than the hole in the chair1 to avoid risk of breaking the casting when driving the spike down4 ,trenails are made out of well-seasoned hard wood1 and are compressed by machinery4 ,when driven into the sleeper1 they expand by exposure to the atmosphere1 and hold the chair very securely in position2 but being only wood and of very small scantling1 they are subject to early decay4 ,the head1 which is the only part in sight1 may be perfectly sound1 while the part between the chair-seat and top of sleeper may be quite rotten and useless4 ,it would be very risky to depend upon trenails alone2 one spike at least should be used to every chair4 ,in some cases an extra large trenail is used with an augur-hole down the centre1 through which either an iron spike is driven or a bolt is passed and screwed into a crab-nut on the under side of the sleeper4 ,this arrangement will work well for a time1 but there will be a great deal of play in the spike or bolt when the trenail becomes much decayed4 ,the spikes represented in ,figs4 #cbf1 #cbg1 and #cbh1 are much used with flange rails4 ,they are square in section1 and finished with either blunt or sharp points1 as shown4 ,the top of spike is made with a doghead and side-lugs to facilitate the easing or withdrawal when necessary for renewals of sleepers1 or alterations in line4 ,by inserting the curved double claw end of a platelayers' crowbar1 the spike can be raised without injuring the sleeper2 but if it is required to be driven into the same sleeper again1 a new hole must be bored1 as the old hole will be too slack to be of any service4 ,augur-holes must be bored in the sleepers for the above spikes4 ,for new roads1 these holes can be bored by machinery when cutting the grooves for rail-seats2 but when carrying out alterations or repairs1 a large number of spike-holes must be bored by hand-augurs1 an operation both slow and laborious4 ,with the hand-boring there is the danger that the hole may not be made deep enough1 owing to the workman's #bbc endeavour to avoid damaging the point of his augur by forcing it entirely through the sleeper1 and bringing it in contact with a stone4 ,augur-holes bored wide to gauge will remain out of gauge1 and although the spike may be driven down firm in its position1 a space will be left for play between the rail-flange and spike4 ,fig4 #cbi is a sketch of a dog-spike for flange rails which the writer has used for many years both abroad and at home1 and which can be driven without any boring at all4 ,the back of this spike is made perfectly straight1 half of the front side is made parallel to the back1 and the remainder is tapered down to a chisel point not exceeding #a_/af of an inch thick1 the entering edge on the face being narrowed down to #c_/h of an inch in width4 ,three jags or spurs are cut on each side of the tapered portion1 or twelve in all1 and add greatly to the holding power4 ,not only can this spike be driven without any boring1 but it possesses the additional advantage that in driving it down its taper or wedge-like shape causes it to drift hard up to the edge of the flange of rail1 an element of great value in securing the exact gauge of line4 ,with these spikes permanent-way laying can be carried on very rapidly1 and they are especially valuable when making alterations1 as augurs for spike-boring can be dispensed with altogether4 ,wood screws with square heads similar to ,fig4 #ccj are sometimes used for fastening flange rails to wooden sleepers4 ,they are passed through holes punched or drilled in the flanges of the rails1 and are intended to preserve the gauge as well as secure the rails to the sleepers4 ,experience has shown that these wood screws possess very limited holding power4 ,the screwed portion of the bolt cuts but a very imperfect and weak holding thread in the soft wood of an ordinary sleeper1 moisture insinuates itself into the bolt-hole1 rusting the bolts and decaying the surrounding timber1 and in a very short time the bolts become loose and incapable of holding the rail down firmly4 ,as permanent-way fastenings wood screws are very inferior to crab bolts4 ,crab bolts1 as in ,fig4 #cca1 may be made either with square or hexagonal heads1 and with three spur-nuts or four spur-nuts1 as in ,a or ,b4 ,the length of the bolts will depend upon the thickness of the sleeper or timber-work through which they have to be inserted4 ,the bolt is pushed down through the hole bored in the sleeper1 and the crab-nut put on from underneath4 ,with a few turns of the bolt1 the #bbd crab-nut is brought close up to the under side of the sleeper1 the spur-points become embedded in the wood1 and hold the nut firmly in position during subsequent tightening of the bolt4 ,crab bolts are extensively used with flange or flat-bottomed rails1 and also in switch chairs and in crossings4 ,a large number of flange rails are used with one hole through the flange at each end of rail1 and a crab bolt passed through the hole and through the sleeper next to the joint1 as shown in ,fig4 #ccb4 ,this system checks the creeping of the rails by effectually securing or anchoring each rail to two of the sleepers4 ,as there is always a tendency for these rails to crack through to the outside at the flange-holes1 it is very desirable to have as few holes as possible4 ,the two above described will be found sufficient for all practical purposes4 ,to avoid punching or drilling more holes in the flanges of the rails1 additional or intermediate crab bolts can be used by means of the fang clips shown on ,fig4 #ccc4 ,the crab bolt is passed through the fang clips and through the sleeper close up to the flange of rail1 and by screwing it round in the crab-nut under the sleeper the fang-clip is pressed down until the two spurs are driven into the timber1 and the rail held securely in its place and to gauge4 ,intermediate crab-nuts and fang-clips should always be used in pairs1 one on each side of the rail4 ,possessing more holding-down power than ordinary spikes1 they are particularly valuable on sharp curves4 ,in some cases flange rails are laid in small cast-iron saddles1 or chairs1 as shown in ,fig4 #ccd1 one end of the rail-seat having a recess to prevent the rail tilting upwards and outwards4 ,an ordinary spike may be used for the inside end of chair1 and a crab bolt with bent washer for the other4 ,unless the fastenings can be kept always tight1 the above arrangement makes a very noisy1 clattering road1 as there are so many metal surfaces in contact1 and so little to deaden the vibration4 ,for narrow flange rails carrying heavy rolling load1 chairs may be necessary to increase the bearing surface on the sleeper1 but with rails having flanges five inches wide and upwards1 it is better to let the flange rest direct on the wood of a properly grooved sleeper1 and thus obtain a smoother and less noisy road4 ,on exceptionally sharp curves1 wrought-iron or steel tie-bars1 as in ,fig4 #cce1 are sometimes used to maintain the line to gauge4 ,they may be made out of bars #c inches wide by an inch thick1 turned over at #bbe the ends to grip the outside flanges4 ,being made to exact template1 they have to be threaded on to the rails before spiking down1 and are placed between the sleepers at distances from #g to #aj feet apart4 ,laying ,permanent ,way4--,to preserve a good line and level to the permanent way1 it is absolutely necessary that the road-bed should be kept thoroughly drained4 ,if provision be not made for quickly carrying away the rain-water1 and if it be allowed to collect under and around the sleepers1 the action of the passing trains will work the finer particles of the packing into the consistency of soft mud1 which will be gradually squeezed away1 leaving the sleepers imperfectly supported and insecure4 ,a loose sleeper involves a depression in the rails1 and a corresponding lurch in the vehicles of the train1 and a series of these depressions may produce such an oscillation in the train as to cause it to leave the rails4 ,the height or space from formation-level to rail-level is generally about #a foot #i inches for a flange railroad1 and about #b feet for a chair railroad4 ,figs4 #ccf and #ccg show cross-sections of both descriptions of road as laid down for a double line in cutting4 ,the same arrangement applies to similar roads laid down in embankment1 merely omitting the side-drains or water-tables4 ,the bottom layer of ballast or road-bed should consist of good hard1 quarried1 or broken stones1 each #f inches deep1 set on edge1 firmly and closely hand-packed1 forming a foundation through which the rain-water can be quickly carried away4 ,on the top of this bottom pitching should be placed a #f-;inch layer of broken stone ballast or strong clean gravel1 of which none of the stones should be larger than will pass through a #b-;inch ring4 ,when the sleepers and rails have been laid on this second layer1 and properly packed to line and level1 the top ballasting1 or boxing1 of either broken stones or strong clean gravel1 should be filled in to the form and extent specified4 ,where broken stones are used for the top ballasting none of them should be larger than will pass through a #a-;inch ring4 ,broken stone ballast should only be made from the hardest and soundest description of rock or boulders1 so that1 however small the particles1 they will remain sharp and clean4 ,illustration3 ,fig4 #ccf1 #ccg1 #cci1 #cch1 #cdj1 #cda1 #cdb1 #cdc1 #cdd ,there are many kinds of rock which appear hard and compact when first excavated1 but upon exposure to the weather undergo a complete change1 #bbg developing into soft masses containing too much clay to allow the water to pass through readily4 ,where rock is scarce and gravel plentiful1 the lower layer may be made of the heavier or coarser gravel1 leaving the finer gravel for the upper layer1 or boxing2 but there is no doubt that the broken stone pitching makes the most efficient bottom layer4 ,no gravel ballast should be used which is not free from clay or earthy sand4 ,wherever there are particles of earthy matter1 sufficient to furnish nourishment for vegetable growth1 weeds will quickly spring up1 and once established are most difficult1 if not impossible1 to eradicate4 ,the presence of weeds checks drainage1 and gives an untidy appearance to the line1 besides constantly occupying a large portion of the platelayers' time in their removal4 ,clean cinders1 free from dust or earth1 are much used for upper ballast and boxing1 and being lighter than gravel1 are specially applicable for soft boggy ground4 ,burnt clay1 broken into small pieces1 has been largely adopted in districts where both rock and gravel were difficult to obtain4 ,chalk1 furnace-slag broken small1 crushed brick and sand1 are frequently used as ballast4 ,sand is objectionable where there is high-speed traffic1 as the finer particles rise in the form of dust and deposit themselves on the vehicles and machinery of the train4 ,the water-tables1 or side drains in the cuttings1 should be cut below the formation level1 and to a depth or width sufficient to take away all rain-water1 or water arising from springs4 ,where the material of the cutting is of a loose friable nature1 it may be necessary to protect the sides of the water-tables with low dry stone walls1 as in ,fig4 #cch2 or glazed earthenware pipes may be laid1 as in ,fig4 #cci1 with open joints1 or with grate openings at regular intervals4 ,in some cases substantial side-walls and invert are requisite to carry away the flow of water4 ,timber sleepers intended for the flange railroad should have the rail-seats grooved by machinery to ensure perfect accuracy in the position of the grooves1 and in the angle or inclination of the rail-seats4 ,fig4 #cdj is a side view of part of a sleeper grooved to receive a flange rail4 ,the presence of the grooves materially facilitate the laying of the rails to gauge1 but must not be allowed to interfere with the constant use of the platelayer's gauge4 ,in a similar manner the timber sleepers for the chair road frequently have #bbh the spike-holes bored to template by machinery1 as indicated on ,fig4 #cda4 ,steel or iron sleepers are delivered with the recesses for rails1 and holes for bolts or fastenings formed complete by machinery4 ,the distances apart of the sleepers will be regulated in a great measure by the weight of the rails and the description of the traffic4 ,where light rails are intended to carry heavy engines the sleepers must be laid closer together than would be necessary for heavy rails4 ,the joint being the weakest part of the rail1 it is usual to put the sleepers closer together at that place1 with a view to gain additional support1 to assist the fish-plates in preserving as much as possible a firm unyielding surface at the rail-joint4 ,fig4 #cdc shows an arrangement of sleepering largely adopted for steel flange rails #bf feet long1 and weighing #gi lbs4 per yard4 ,the length of a rail is more a question of convenience of handling1 facility of transhipment1 and general use1 than of actual manufacture4 ,there is no difficulty in rolling rails up to #ej feet in length1 or more2 but very long rails are extremely ungainly things to move about1 and are more exposed to receive permanent bends or kinks in unloading1 besides requiring greater spaces at the joints to allow for contraction and expansion4 ,fig4 #cdd is an example of sleepering for a chair railroad1 for steel bull-head rails #bf feet long1 and weighing #he pounds per yard4 ,line stakes and level pegs must be put in at suitable distances to guide the platelayers in laying the rails to the correct line and level1 and on the curves the proper amount must be marked off for the super-elevation of the outer rail4 ,when the second layer of ballast has been spread for its full width and depth the sleepers can be distributed1 and the rails or chairs spiked down to the correct gauge4 ,before putting on the fish-plates spaces must be left at the ends of the rails to allow for contraction and expansion1 the amount depending upon the temperature at the time of laying down the rails4 ,as the rails will expand1 or increase in length1 with the heat1 it is necessary to allow more space for expansion for rails laid down in the cold1 or winter months4 ,on our home railways rails are very rarely laid down when the temperature is lower than #be ,f41 or higher than #abe ,f41 and this range of #ajj may be considered as covering all the variations likely to occur in ordinary practice4 ,the greater portion of the permanent-way laying is #bbi carried on when the temperature is between #dj and #ge4 ,the results of very carefully conducted experiments show that an increase of temperature of #a ,f4 will cause an iron or steel bar1 or rail1 to expand or lengthen to the extent of seven one-millionths of its length4 ,working this out for a range of #ajj ,f4 would give an increase in length of seven hundred one-millionths1 which would be equal to an extension of #jbahd of an inch in a #bf-;foot rail4 ,for our home railways1 therefore1 a space of #e_/af of an inch will be found amply sufficient to meet the variations in length between the extremes of winter and summer1 for a rail from #bf feet to #cj feet in length4 ,too much allowance for expansion is detrimental to the rails1 because where the spaces are excessively large the wheels drop into the hollow and hammer or spread the ends of the rails4 ,the fish-bolts should not be completely tightened up until the permanent way is thoroughly set1 and packed to its finished line and level4 ,on straight line the rail-joints should be laid square and opposite to each other4 ,permanent-way laying with broken joints is rarely adopted1 except on curves or station-yards4 ,on curves the joints of the inner rails gain on the joints of the outer rails to the extent of-- radius gauge -------------- length of rail4 radius ,the amount of this gain1 or lead1 is adjusted by cutting off a portion of the end of the inner rails at certain intervals4 ,assuming the fish-bolt holes to be spaced as shown on ,fig4 #cdb1 then1 when the inner rail is leading to the extent of #b inches1 a piece #d inches long is cut off1 as shown by dotted lines1 leaving the original second fish-bolt hole to serve as first or end fish-bolt hole1 and a new or second bolt-hole is drilled by hand at ,a4 ,this method sets back the joint #b inches from the square1 and the lead is allowed to go on again until it becomes necessary to cut off another piece of #d inches4 ,another mode is to have a proportion of the rails rolled #b or #c inches shorter for use on the curves4 ,on curves of a #ajjj feet radius and upwards1 the rails should be laid to the normal gauge1 but on curves of lesser radius the gauge may be slightly increased1 and as much as of an inch allowed on a curve of #ejj feet radius4 ,the amount of cant1 or super-elevation1 to be given to the outer rail #bcj on curves must be regulated by the speed of the train and the gauge of the line4 ,many formul have been compiled to determine the necessary amount of super-elevation1 but experience has shown that by some of them the calculated amounts were excessive4 ,possibly during past years too much cant has been given in many cases4 ,the following simple formula approaches very closely to practical experience-- 7velocity in miles per hour7#b gauge in feet the super-elevation ---------------------------------------- ------- of outer rail radius in feet #abe in inches4 ,for high-speed trains uniformity of cant is of the utmost importance1 more so even than the exact amount4 ,any irregularity in the super-elevation of the outer rail1 sometimes high and sometimes low1 will produce a dangerous swaying movement in the train1 which1 if not promptly checked1 would lead to derailment4 ,more injury is done to curves by spreading1 arising from rigid wheel-bases of engines and tenders1 than from any want of counteraction to centrifugal force4 ,when a long length of permanent way has been linked in1 rails spiked to gauge1 and fish-plates bolted together1 the platelayers can proceed to the final adjustment to line and level in accordance with the stakes and pegs provided for their guidance4 ,the setting to exact line is effected by means of long pointed round iron crowbars1 which are struck forcibly into the ballast alongside the rails1 and serve as powerful hand-levers to pull or push the rails to the right or left as directed by the foreman standing some distance back at one of the line-stakes4 ,the men with the crowbars pass from rail-length to rail-length1 until a long stretch of road has been pulled into correct line4 ,the adjustment to rail-level is done by first packing up the sleepers to the correct height at the various level-pegs1 and then packing up the intermediate sleepers so that the surface of the top of the rails forms one uniform even line from level-peg to level-peg4 ,on new lines it is usual to pack a little high in the first instance to allow for the subsidence or compression which invariably takes place on the passage of heavy trains over fresh ballast4 ,the form or contour line of the top ballast will vary according to #bca circumstances4 ,in station-yards it is usual to fill in the ballast almost up to the level of the top of the rails for the convenience and safety of the men who are constantly moving about marshalling the carriages and waggons4 ,out on the open line between stations1 the ballast on some railways is filled in up to rail-level1 while on others it is only filled in up to the tops of the sleepers1 leaving the rails and chairs quite clear of the ballast4 ,on others1 again1 the ballast is filled well up to the rails and channelled in the centre1 as shown on the sketches ,figs4 #ccf and #ccg4 ,channelling the centre of the road reduces the quantity of ballast per mile1 ensures good drainage1 and also stability by not permitting any central support to the sleepers4 ,by covering up the lower table and sides of rails the noise is reduced to a minimum1 vibration is absorbed1 and a more silent road is the result4 ,the contact with the ballast also preserves the rail from the extremes of temperature4 ,where the ballasting is not channelled there is some risk of the sleepers breaking in the middle4 ,the constant packing of the sleepers just under the rails has a tendency to drift some of the ballast inwards towards the middle of the sleeper1 forming a hard compact mass1 and this mass1 acting as fulcrum1 throws considerable strain on the middle of the sleeper when the trains pass over and depress the ends4 ,where the ballast is filled in level with the rails on top of sleepers it should be loosened occasionally in the middle to prevent it becoming too hard4 ,connections with the rails of the main line will have to be made in various forms to suit the circumstances of the joining lines or sidings4 ,fig4 #cde shows a simple double-line junction4 ,illustration3 ,fig4 #cde1 #cdf1 #cdg1 #cdh1 #cdi1 #cej1 #cea1 #ceb1 #cec1 #ced1 #cee1 #cef ,fig4 #cdf shows an example of what is termed a flying junction1 or a junction of two double lines arranged in such a manner as to cause the least interruption to a constant train traffic passing ,,up and ,,down over both lines4 ,upon referring to ,fig4 #cde it will be seen that a train from ,f1 turning off at the points ,e and proceeding to ,g1 must block1 or close for traffic the section ,,abc during its passage over that line towards ,g4 ,with a crowded train-service the blocking of both ,,up and ,,down main lines for the working of one train would cause much interruption1 and to obviate such delay the flying junction is substituted4 ,fig4 #cdf shows how a train from ,f is turned off at the points ,j and proceeds on to ,k1 where by means of a bridge it passes either over or under both main lines1 and #bcc continues on to ,g without in any way interfering with the train service on ,,abc4 ,fig4 #cdg is an ordinary plain siding or turn-out1 including the necessary throw-off or trap-points and short dead end4 ,fig4 #cdh is an ordinary cross-over road from ,,down main line to ,,up main line1 and vice vers4 ,fig4 #cdi is a double cross-over road1 generally termed a scissors cross-over4 ,fig4 #cej is a simple through cross-over road from ,,down main line to siding alongside ,,up main line4 ,fig4 #cea is a similar arrangement of through cross-over road with the addition of a pair of slip points at ,s to make a connection with the ,,up main line1 thus combining the facilities of the ordinary cross-over and through cross-over road4 ,fig4 #ceb shows a set of three throw-switches with all the sliding tongues placed side by side2 and ,fig4 #cec shows another arrangement of three throws with the sliding-rails of the second set of switches placed just behind the heel of the first set of switches4 ,the latter method works very well where there is sufficient length for the purpose4 ,fig4 #ced shows a square crossing1 where one line of railway crosses another line of railway on the same level4 ,fig4 #cee shows a connection with a siding by means of an ordinary carriage or waggon turn-table4 ,fig4 #cef shows a set of 8runaway0 points which are sometimes placed in the main line at the top of an incline close to a station1 the object being to intercept or throw off any portion of a train which may have become detached1 and which would1 if unchecked1 run away back down the incline4 ,by means of a weighted lever or spring the points are set to the normal position of open to the siding1 and as they are 8trailing0 points for the running road they are readily closed by a passing train4 ,one or other of the above forms of connections1 or a combination of them1 will meet all the requirements which usually occur in railway work4 ,fig4 #ceg is an enlarged sketch of an ordinary cross-over road1 and ,fig4 #ceh of a double or scissors cross-over4 ,illustration3 ,fig4 #ceg1 #ceh ,fig4 #cei shows a single-slip point connection1 and ,fig4 #cfj a double-slip point connection4 ,in places where slip connections can be introduced they add greatly to the facilities for train movements #bce without curtailing the available standing-room for vehicles on the lines and sidings4 ,they are simple in construction1 do not require crossings1 and in many cases save a complete cross-over road4 ,at the same time slip connections can only be laid down where the angle of the intersecting lines is sufficiently flat to admit of a connecting curve of workable radius4 ,fig4 #cfa is an enlarged sketch of a set of ordinary #ae-;foot switches or points4 ,by placing them about the middle of the stock rails the joints of the latter are kept well beyond the sliding rails1 and the road is held firmly together4 ,it is necessary to place the sleepers closer together at the switches to allow for the reduction in section of the sliding rails1 which results from planing them down to the requisite shape4 ,by substituting two long timbers for the ordinary sleepers at the points of the switch rails1 as shown on the sketch1 a more efficient support is obtained for the switch-box or crank in the case of rod-worked switches1 and the working distance from the rails is accurately maintained1 irrespective of any packing or pulling of the road4 ,in the sketch a steel bull-head rail is shown on one side1 and a steel flange rail on the other1 each bolted to an ordinary cast-iron switch chair4 ,switch chairs are sometimes made of plates of wrought-iron or steel1 forged to the correct shape1 and riveted together4 ,they are1 however1 much more costly than cast-iron chairs1 and deteriorate more quickly from corrosion4 ,illustration3 ,fig4 #cei1 #cfj ,fig4 #cfb is an enlarged sketch of an ordinary crossing similar to the one indicated at ,c 7,fig4 #cei71 and composed of a cast-steel reversible block4 ,the ends and lugs1 ,l1 ,l1 are formed to suit the connecting rails and fish-plates1 as shown in the cross-sections4 ,the casting is secured to the crossing timbers by bolts passing through the side lugs1 ,s1 a cast-iron packing-washer1 ,w1 being placed between the lug and the timber to ensure a solid seat and avoid rocking4 ,a very important point in the construction of these block crossings is to have the groove or flange-path sufficiently deep to prevent the striking or touching of the flange of a much-worn tyre4 ,a well-made1 carefully annealed steel-block reversible crossing is very smooth in the road1 and has a long life4 ,it is all in one solid piece2 there are no parts to work loose or spread2 the wear of the running surface is very uniform1 and when the one side is much worn down1 there is the other ready for service4 ,the writer has had many of these steel-block reversible crossings in use under heavy and fast traffic #bcg for six and eight years without turning4 ,fig4 #cfc shows an ordinary crossing made of steel bull-head rails secured in strong cast-iron chairs2 and ,fig4 #cfd is a similar crossing made of steel flange rails4 ,in some cases the two rails forming the ,v are welded together at the point ,b1 and in others they are riveted or bolted together4 ,fig4 #cfe shows a diamond or through crossing similar to the one indicated at ,d1 ,fig4 #cei1 made of steel bull-head rails and chairs4 ,crossings are constructed in a variety of forms1 whether on the principle of the cast-steel block1 or made out of ordinary steel rails2 and the above sketches merely illustrate some well-recognized types which experience has proved to be efficient and durable in the road4 ,the angles of the crossings will depend upon the divergence of the intersecting lines to be connected2 ordinary crossings1 to the angle of #a in #aj1 work in for very general use in station-yards1 but many are required of angles varying from #a in #f to #a in #ad1 and in some cases #a in #af4 ,as a rule1 engineers endeavour as far as possible to avoid using ordinary crossings flatter than #a in #ab1 or diamond crossings flatter than #a in #i1 because the gap between the running rails becomes very considerable beyond those angles4 ,at the same time1 there are many cases of ordinary crossings of #a in #af1 and diamond crossings of #a in #ab and #a in #ac laid down in exceptional places1 and which have carried heavy and fast traffic for many years4 ,all crossings should be well protected with wing rails and guard rails1 as shown on the sketches4 ,fig4 #cff illustrates a method of bringing the ,,up and down lines of a double line of railway close to each other1 and passing them over a single-line opening bridge1 or a bridge where the works for the second line have not been completed4 ,this arrangement avoids the necessity of any switches1 and prevents any accidents which would arise from a misplaced switch4 ,each set of trains is effectually kept to its own line of rails4 ,with proper signalling or pilot working1 the double-line traffic can be worked over the single-line bridge without difficulty4 ,the writer has adopted the above arrangement in many cases when renewing double-line bridges or viaducts where the width for traffic working has been restricted to half of the bridge4 ,illustration3 ,fig4 #cfa1 #cfb1 #cfc1 #cfd1 #cfe ,in some instances the same system has been extended to the carrying of #bci four lines of rails over a double-line bridge1 as shown on ,fig4 #cfg4 ,the principal tool used by platelayers for lifting the permanent way is a long iron-shod wooden lever1 as shown in ,fig4 #cfh4 ,the point of the lower end is pushed under the sleeper1 and the curved shoulder placed on a large stone or piece of wood as a support1 and then by pulling down the upper end of the lever the road can be lifted to the height required4 ,screw lifting-jacks of various kinds are also used for the same purpose1 the foot or base of the jack resting on the ballast1 while the claws grasp the under side of the rail1 and raise it by means of the screw4 ,with appliances which lift by the rails1 the sleepers have to be raised by the holding power of the spikes or bolts1 an operation which is apt to throw undue strain on spikes4 ,where possible it is preferable to lift from the under side of the sleepers4 ,beaters similar to the one shown on ,fig4 #cfi are used for packing the ballast4 ,one end of the beater is pointed like a pick1 and serves to loosen the ballast or broken stone1 and the other end is made somewhat in the hammer-head form to pack or beat the ballast under the sleeper4 ,with skilled men the beater is a most useful tool1 speedy and effective in its action4 ,held in both hands1 it is raised slightly1 and then brought down sharply1 the hammer-head striking the gravel or broken stone placed alongside for packing under the sleeper4 ,a series of smart blows can be given with rapidity and without requiring any great muscular effort4 ,in some foreign countries there is difficulty in initiating the natives to work with the ordinary beater1 on account of the stooping position necessary for its use4 ,to meet this difficulty the writer has in many cases substituted a packing or tamping bar1 as shown in ,fig4 #cgj4 ,this bar1 about #e feet long1 is made of light round wrought-iron or steel1 with a ring-shaped handle at one end1 and an ordinary beater head at the other4 ,the workman using this bar stands upright1 guides the bar1 held loosely1 with his left hand1 and with his right gives a continuance of smart blows4 ,this tool works well in the hands of light active natives1 who can thus give a number of rapid strokes without much exertion4 ,illustration3 ,fig4 #cff1 #cfg1 #cfh1 #cga1 #cfi1 #cgj1 #cgb ,the simple rail-bender1 or ,jim ,crow1 of the form shown in ,fig4 #cga1 is much used by platelayers for giving a slight bend or set to rails which have to be laid down on sharp curves on main line or cross-over roads4 ,the rail is laid across the two arms1 and the screw turned round #bda and downwards by means of an iron bar lever used as a spanner or wrench to the nut shown on the sketch4 ,the same tool is also serviceable for straightening rails which have become crooked or kinked4 ,large and more comprehensive machines are used for bending rails in large quantities or setting them to exact curvature1 but1 being heavy and cumbersome1 they are rarely taken away from the store-yards4 ,strong steel shovels of the form shown in ,fig4 #cgb are the most suitable for platelayers' general use when working with gravel1 sand1 or broken stones4 ,for driving iron spikes and wooden keys in cast-iron chairs a long-handled hammer is the most convenient for work1 and its long swinging action produces considerable force without much actual labour4 ,road-gauges1 nut-wrenches1 short straight-edges1 spirit-levels1 ratchet-drills1 augurs1 and cold setts of well-tempered steel for cutting rails1 are all required by the men engaged in laying permanent way4 ,the following summaries give the estimated cost of materials alone for one mile of steel bull-head rail and steel flange rail permanent way of different weights4 ,the #ij-lb4 steel bull-head rail is at present the heaviest of that section laid down to any extent on our home railways1 and the chairs and fastenings are made heavy to correspond to the rail and the traffic for which it is intended4 ,as the rails in the summaries become lighter1 the weights of the chairs and fastenings are decreased4 ,as yet there are not many samples of the #ajj-lb4 steel flange rail2 but in those places where it has been laid down it has been supported with a liberal supply of sleepers1 to obtain increased bearing surface4 ,with a #e-;inch flange1 and a rectangular sleeper #aj inches wide1 the bearing surface on the wood is only about #ee square inches1 as compared with about #ajj square inches1 the bearing surface of a large cast-iron chair for a heavy bull-head rail4 ,as previously explained1 a small bearing surface on a sleeper tends to the cutting down into the wood1 and rendering the sleeper unsafe and useless even before it has become unserviceable from decay3 hence the reason for ample bearing surface on the sleeper4 ,the last two summaries refer to #c-;foot narrow-gauge lines4 ,in more than one instance the #de-lb4 rails first laid down have been found much too light for the engines required to work the traffic1 and when making extensions of the system #bdb #fe-lb4 rails have been adopted4 ,indeed1 when taking into consideration the weight of most of the narrow-gauge engines1 generally from #bd to #bh tons in working order1 and their short wheel-base1 it would appear that a #fe-lb4 rail is the minimum which should be used both for stability and economy in maintenance4 ,the summaries are prepared from examples in actual use1 and represent the number and weight of sleepers1 chairs1 and fastenings in each instance4 ,even with the same weight of rail1 the practice differs on various lines as to the weights of the chairs and fastenings2 and the selections have been made to show a fair average4 ,on some railways the chairs are secured partly by tree-nails and partly by spikes1 or crab bolts2 on others only spikes are used4 ,the prices put down are the estimated values of the materials delivered into the ,permanent ,way ,stores of our own home railways1 and are exclusive of all costs of freight1 carriage1 or distribution to the site of laying down4 ,the prices are only comparative1 and fluctuate up or down according to the current value of the raw materials from which the various items are manufactured4 ,lighter rails and smaller fastenings cost more per ton than those of a heavier type1 as they involve more labour and workmanship4 ,,steel ,,bull-,,head ,,rails 7#ij ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------- ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------- tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel bull-head rails1 #ij lbs4 per yard 7#cj-;ft4 lengths7 #ada #h #b #j #e #j #j #gjg #b #f ,steel fish-plates 7deep71 #da lbs4 per pair #f #aj #j #j #f #ae #j #dc #ag #f ,fish-bolts and nuts #a #d #j #j #ab #ae #j #ae #f #j #baab creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #djd #af #j #dbbd cast-iron chairs1 each #ej lbs4 #id #e #c #j #c #aj #j #ccj #j #a #hddh iron cup-headed spikes #c #ae #b #j #aj #j #j #cg #ae #j #hddh tree-nails1 at per #ajjj -- #c #aj #j #bi #aa #d #dbbd oak keys1 at per #ajjj -- #e #j #j #ba #b #e ---------------------------------------- ------------------------------- #aehi #aj #aj ---------------------------------------- --------------------------------- ,,steel ,,bull-,,head ,,rails 7#he ,,lbs4 ,,per ,,yard74 #bdc ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------- ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------- tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel bull-head rails1 #he lbs4 per yard 7#bf-;ft4 length 7 #acd #j #j #j #e #j #j #fgj #j #j ,steel fish-plates 7deep71 #ch lbs4 per pair #f #ag #c #j #f #ae #j #df #i #aj ,fish-bolts and nuts #a #d #c #j #ab #ae #j #ae #ae #g #bjcj creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #chi #a #h #djfj cast-iron chairs1 each #de lbs4 #ha #aa #a #j #c #aj #j #bhe #i #e #habj iron cup-headed spikes #c #ab #b #j #aj #j #j #cf #e #j #djfj tree-nails1 at per #ajjj -- #c #aj #j #ad #d #b #djfj oak keys1 at per #ajjj -- #e #j #j #bj #f #j ---------------------------------------- ------------------------------- #adgg #aa #h ---------------------------------------- --------------------------------- ,,steel ,,bull-,,head ,,rails 7#hj ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------- ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------- tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel bull-head rails1 #hj lbs4 per yard 7#bf-;ft4 lengths7 #abe #ad #j #j #e #j #j #fbh #aj #j ,steel fish-plates 7deep71 #cg lbs4 per pair #f #ad #a #j #f #ae #j #de #f #b ,fish-bolts and nuts #a #d #c #j #ab #ae #j #ae #ae #g #bjcj creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #chi #a #h #djfj cast-iron chairs1 each #dj lbs4 #gb #aj #j #j #c #aj #j #bec #ae #j #habj iron cup-headed spikes #c #ab #b #j #aj #j #j #cf #e #j #djfj tree-nails1 at per #ajjj -- #c #aj #j #ad #d #b #djfj oak keys1 at per #ajjj -- #e #j #j #bj #f #j ---------------------------------------- ------------------------------- #adjc #c #g ---------------------------------------- --------------------------------- ,,steel ,,bull-,,head ,,rails 7#ge ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel bull-head rails1 #ge lbs4 per yard 7#bf-;ft4 lengths7 #aag #j #j #j #e #j #j #ehe #j #j ,steel fish-plates 7deep71 #ce lbs4 per pair #f #g #j #j #f #ae #j #db #ag #c ,fish-bolts and nuts #a #d #c #j #ab #ae #j #ae #ae #g #bjcj creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #chi #a #h #djfj cast-iron chairs1 each #cg lbs4 #fg #a #a #j #c #aj #j #bcd #ad #e #ab1ahj iron cup-headed spikes #e #h #c #j #aj #j #j #ed #g #f #djfj oak keys1 at per #ajjj -- #e #j #j #bj #f #j ---------------------------------------- ------------------------------ #acdb #b #e ---------------------------------------- ------------------------------ ,,steel ,,bull-,,head ,,rails 7#gj ,,lbs4 ,,per ,,yard74 #bdd ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel bull-head rails1 #gj lbs4 per yard 7#bf-;ft4 lengths7 #aaj #j #j #j #e #j #j #eej #j #j ,steel fish-plates 7deep71 #cb lbs4 per pair #e #af #j #j #f #ae #j #ci #c #j ,fish-bolts and nuts #a #b #j #j #ab #ae #j #ad #j #f #bjcj creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #chi #a #h #djfj cast-iron chairs1 each #cd lbs4 #fa #ab #b #j #c #aj #j #bae #ac #i #habj iron cup-headed spikes #c #c #b #j #aj #j #j #ca #ae #j #djfj oak keys1 at per #ajjj -- #d #aj #j #ah #e #e ---------------------------------------- ------------------------------ #abeg #ai #d ---------------------------------------- -------------------------------- ,,steel ,,bull-,,head ,,rails 7#fe ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------- ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------- tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel bull-head rails1 #fe lbs4 per yard 7#bf-;ft4 lengths7 #ajb #c #j #j #e #e #j #ecf #e #i ,steel fish-plates 7deep71 #bh lbs4 per pair #e #a #b #j #g #j #j #ce #aj #f ,fish-bolts and nuts #a #a #j #j #ac #j #j #ac #ac #j #bjcj creosoted sleepers1 #i ft4 #i in4 #d in4 -- #j #c #j #cjd #aj #j #djfj cast-iron chairs1 each #bh lbs4 #ej #ae #j #j #d #j #j #bjc #j #j #habj iron cup-headed spikes #b #ai #j #j #aj #aj #j #cj #ai #f #djfj oak keys1 at per #ajjj -- #d #j #j #af #d #i ---------------------------------------- ------------------------------- #aadj #c #f ---------------------------------------- --------------------------------- ,,steel ,,flange ,,rails 7#ajj ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------- ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------- tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #ajj lbs4 per yard 7#cj-;ft4 lengths7 #aeg #c #j #j #e #j #j #ghe #ae #j ,steel fish-plates 7deep71 #db lbs4 per pair #f #ab #j #j #f #aj #j #db #ah #j ,fish-bolts and nuts #a #e #j #j #ab #ae #j #ae #ah #i #bdfd creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #dgb #e #d #hddh dog-head spikes #c #f #j #j #ab #aj #j #da #e #j #gjd fang clips #j #h #c #j #ac #aj #j #e #ah #b #adjh crab bolts #a #f #c #j #ab #aj #j #af #ad #e ---------------------------------------- ------------------------------- #achj #ad #h ---------------------------------------- --------------------------------- ,,steel ,,flange ,,rails 7#gi ,,lbs4 ,,per ,,yard74 #bde ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #gi lbs4 per yard 7#bf-;ft4 lengths7 #abe #j #j #j #e #j #j #fbe #j #j ,steel fish-plates 7deep71 #cg lbs4 per pair #f #ad #a #j #f #aj #j #dc #ab #h ,fish-bolts and nuts #a #d #j #j #ab #ae #j #ae #f #j #bjcj creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #chi #a #h #fdif dog-head spikes #b #aj #c #j #ab #aj #j #ca #ad #e #hab fang clips #j #aj #j #j #ac #aj #j #f #ae #j #afbd crab bolts #a #aj #c #j #ab #aj #j #ai #d #e ---------------------------------------- ------------------------------ #aacj #ad #b ---------------------------------------- -------------------------------- ,,steel ,,flange ,,rails 7#gd ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #gd lbs4 per yard 7#cj-;ft4 lengths7 #aaf #e #c #j #e #j #j #eha #h #i ,steel fish-plates 7deep71 #cj lbs4 per pair #d #ae #c #j #f #aj #j #ca #b #e ,fish-bolts and nuts #a #a #j #j #ab #ae #j #ac #g #i #aicf creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #cga #a #d #fccf dog-head spikes #b #i #b #j #ab #aj #j #cj #ah #i #gjd fang clips #j #h #c #j #ac #aj #j #e #ah #b #adjh crab bolts #a #f #c #j #ab #aj #j #af #ad #e ---------------------------------------- ------------------------------ #ajej #aa #g ---------------------------------------- -------------------------------- ,,steel ,,flange ,,rails 7#fe ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #fe lbs4 per yard 7#cj-;ft4 lengths7 #ajb #c #j #j #e #aj #j #efa #af #f ,steel fish-plates 7deep71 #bg lbs4 per pair #d #d #c #j #g #e #j #cj #ad #e ,fish-bolts and nuts #a #j #j #j #ac #j #j #ac #j #j #aicf creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #cga #a #d #fccf dog-head spikes #b #i #b #j #ab #aj #j #cj #ah #i #gjd fang clips #j #h #j #j #ac #aj #j #e #h #j #adjh crab bolts #a #f #c #j #ab #aj #j #af #ad #e ---------------------------------------- ------------------------------ #ajbi #ac #e ---------------------------------------- -------------------------------- ,,steel ,,flange ,,rails 7#fj ,,lbs4 ,,per ,,yard74 #bdf ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #fj lbs4 per yard 7#cj-;ft4 lengths7 #id #e #c #j #e #aj #j #eah #aa #g ,steel fish-plates 7deep71 #be lbs4 per pair #c #ah #b #j #g #e #j #bh #i #b ,fish-bolts and nuts #a #j #j #j #ac #j #j #ac #j #j #baab creosoted sleepers1 #i ft4 #aj in4 #e in4 -- #j #c #aj #djd #af #j #gjdj dog-head spikes #b #ae #j #j #ab #aj #j #cd #g #f #gjd fang clips #j #h #j #j #ac #aj #j #e #h #j #adjh crab bolts #a #f #c #j #ab #aj #j #af #ad #e ---------------------------------------- ------------------------------ #ajba #f #h ---------------------------------------- -------------------------------- ,,steel ,,flange ,,rails 7#ej ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line4 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #ej lbs4 per yard 7#cj-;ft4 lengths7 #gh #aa #b #j #e #ae #j #dea #af #a ,steel fish-plates 7deep71 #bb lbs4 per pair #c #i #a #j #g #aj #j #be #ai #e ,fish-bolts and nuts #j #ah #j #j #ac #aj #j #ab #c #j #baab creosoted sleepers1 #i ft4 #i in4 #d in4 -- #j #c #j #caf #af #j #gjdj dog-head spikes #b #g #a #j #ac #j #j #cj #ad #c #gjd fang clips #j #f #a #j #ad #j #j #d #g #f #adjh crab bolts #a #b #j #j #ac #j #j #ad #f #j ---------------------------------------- ------------------------------ #hef #b #c ---------------------------------------- -------------------------------- ,,steel ,,flange ,,rails 7#fe ,,lbs4 ,,per ,,yard74 ,estimated ,cost of ,materials for ,one ,mile of ,single ,line 7#c-;ft4 gauge74 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #fe lbs4 per yard 7#cj-;ft4 lengths7 #ajb #c #j #j #e #aj #j #efa #af #f ,steel fish-plates 7deep71 #bg lbs4 per pair #d #d #c #j #g #e #j #cj #ad #e ,fish-bolts and nuts #a #j #j #j #ac #j #j #ac #j #j #bbhh creosoted sleepers1 #f ft4 #i in4 #d in4 -- #j #b #c #beg #h #j #ggdd dog-head spikes #b #ag #j #j #ab #aj #j #ce #ab #f #gjd fang clips #j #g #b #j #ac #aj #j #e #a #c #adjh crab bolts #b #b #j #j #ab #aj #j #bf #e #j ---------------------------------------- ------------------------------ #ibi #ag #h ---------------------------------------- -------------------------------- ,,steel ,,flange ,,rails 7#de ,,lbs4 ,,per ,,yard74 #bdg ,estimated ,cost of ,materials for ,one ,mile of ,single ,line 7#c-;ft4 gauge74 ---------------------------------------- ------------------------------ ,weight per mile ,price4 ,amount4 of single line4 ---------------------------------------- ------------------------------ tons4 cwt4 qrs4 lbs4 s4 d4 s4 d4 ,steel flange rails1 #de lbs4 per yard 7#bf-;ft4 lengths7 #gj #ad #a #j #e #ae #j #djf #ab #j ,steel fish-plates 7deep71 #af lbs4 per pair #b #ah #j #j #g #aj #j #ba #ae #j ,fish-bolts and nuts #j #ah #j #j #ac #aj #j #ab #c #j #bbcc creosoted sleepers1 #f ft4 #h in4 #d in4 -- #j #a #aj #bjd #ac #aj #gcjh dog-head spikes #b #ad #j #j #ac #j #j #ce #b #j #hab fang clips #j #e #j #j #ad #j #j #c #aj #j #afbd crab bolts #j #ah #j #j #ac #j #j #aa #ad #j ---------------------------------------- ------------------------------ #fie #i #aj ---------------------------------------- -------------------------------- ,,chapter ,,iv4 #bdh ,stations3 ,station ,buildings1 ,roofs1 ,lines1 and ,sidings4 ,stations4--,when selecting a site for a station1 not only should due regard be paid to the proximity and convenience of access to the town or place to be served1 but attention should be given to the gradients of the line near the proposed station4 ,if it can possibly be avoided1 a station should not be placed in a hollow at the foot of two inclines1 as such a position would always entail heavy work starting trains on the ascending gradients1 with the risk of sliding back into the station again in unfavourable weather2 and for arriving trains there would be increased difficulty in properly controlling the vehicles on the descending gradients so as to bring them to a stand in the event of any sudden stoppage being required4 ,with stations on a summit1 having gradients falling in each direction1 the starting trains can get away more readily1 and the arriving trains have the benefit of the rising gradient to assist them in coming to a stand4 ,possibly the best selection would be a long length of level1 both in the station proper and for a considerable distance on each side2 but it is not often that such a combination can be obtained without incurring extra expenditure4 ,the station-yard itself should1 however1 be on the level1 or as nearly so as possible1 for the convenience and safety of marshalling or shunting carriages or waggons4 ,no siding should be laid on such a gradient as would render it possible for vehicles to start into motion during high winds4 ,carriages and waggons having good oil axle-boxes will start themselves on a gradient of #a in #cjj under the influence of a moderately strong breeze1 and a slight push will start them on a gradient of #a in #djj4 ,the number and arrangement of the lines1 sidings1 platforms1 loading banks1 and other conveniences of a station1 will depend upon the description and amount of traffic to be accommodated4 ,there is a wide #bdi range from the simple village station1 with its one short siding1 to the great city terminus1 with its labyrinth of lines and sidings1 and its groups of platforms1 offices1 warehouses1 and other accessories4 ,each station should be laid out with a view to meet the special requirements of the principal traffic likely to arise1 whether passenger1 timber1 coal1 stone1 cattle1 or general merchandise1 and ample space should be retained to permit further enlargement and additional sidings at any future time4 ,if provision is not made for the latter in the outset it will certainly lead to large expenditure at some later date4 ,land adjoining a railway station is quickly appropriated by the public on account of its proximity and convenience for conveyance1 and soon covered with store-yards1 warehouses1 and other buildings1 and when any portion of these have to be acquired for station enlargements1 they can only be obtained at a large cost1 very often ten times as much as the value of the original ground4 ,when laying out approach roads to goods or passenger stations1 whether intermediate or terminal1 due importance should be given to the advantage of making them wide1 easy in gradient1 and fairly straight4 ,a narrow1 crooked access to a busy goods yard is a great impediment to the expeditious working of a heavy traffic2 and road waggons conveying long pieces of timber or ironwork along such a route1 would be very apt to block the roadway and delay the passage of other vehicles4 ,a steep gradient will prevent the carriers taking full loads1 and will add to the cost and time of delivery4 ,illustration3 ,fig4 #cgc ,an approach road to a large passenger station should be laid out with a long frontage to a wide footpath to enable the numerous intending passengers to alight conveniently from the conveyances which bring them to the station4 ,a portion of the footpath and carriage-way in front of the entrance to the booking-hall should be covered over with a light roof to provide shelter during inclement weather4 ,the footpath should be on the same level as the vestibule or booking-hall1 so that the public may pass at once to the ticket-office and their luggage be wheeled on hand-barrows direct to the platform or luggage-room4 ,every effort should be made to avoid introducing steps from the footpath to the booking-hall1 as they check the proper ingress of the passengers1 and are very severe on elderly persons and invalids1 besides necessitating the dilatory method of carrying each piece of the passengers' luggage by hand4 ,experience has shown the inconvenience of #bea steps to be so great that in many cases a large expenditure has afterwards been incurred to do away with them1 and bring the setting-down footpath to the same level as the booking-hall4 ,for a large station the booking-hall should be spacious and well provided with separate ticket windows for the different classes of passengers and districts of the line2 and the access or communication with the platform should be ample and free from obstruction4 ,small doors and narrow passage-ways check the movements of the passengers and create confusion and delay4 ,waiting-rooms for the different classes of passengers1 inquiry-offices1 luggage-rooms1 lavatories1 etc41 will have to be provided according to the amount of traffic to be accommodated4 ,in large stations it may be necessary to have two or more groups of such rooms to suit the different sets of platforms4 ,at the most important terminal stations of our home railways it is usual to lay down the main-line arrival platforms with a cab or carriage rank alongside1 so that the passengers alighting from the railway carriages have merely to walk across the platforms1 and step into the cabs or vehicles waiting to take them and their luggage away from the station4 ,this arrangement is not only a great convenience to the passengers1 but expedites the clearing of the platform and the making way for another incoming train4 ,it would not1 however1 be of any service on continental lines1 or other foreign railways1 where all arriving luggage must first be taken to the general luggage room1 to be examined by the local customs1 or octroi officers1 before being allowed to pass out of the station4 ,illustration3 ,fig4 #cgd1 #cge ,main-line departure platforms should be of ample width to allow of the free movement of the passengers1 ticket examiners1 officials1 and men wheeling passengers' luggage4 ,the accommodation should not only be sufficient for the normal traffic1 but allowance should be made for the large crowds which may assemble for excursion trains during the holiday season or other occasions of national gathering4 ,additional or local platforms1 frequently termed dock platforms1 may be required for suburban trains1 and may be made narrower in width1 and without cab ranks1 as the passengers using them only travel short distances and rarely have more luggage than they carry in their hands4 ,these dock platforms are generally made available for outgoing as well as #bec incoming trains4 ,the lengths of the main-line or local platforms will be regulated by the number of carriages forming a train4 ,fig4 #cgc is a diagram sketch of a large terminal passenger station1 with main and local platforms as above described4 ,it is merely typical to illustrate the principle1 and may be multiplied and varied to any extent in the way of lines and platforms4 ,in the sketch the main groups of offices1 waiting-rooms1 etc41 are shown at the end of the station2 but they may be equally well placed at the side1 as their actual location is principally a question of proximity or convenience of access to some main street or thoroughfare4 ,the lower or platform-level rooms of such a building are mainly devoted to the public for booking-offices1 waiting-rooms1 refreshment-rooms1 lavatories1 offices for parcels1 telegraph and inquiry1 suitable rooms being set apart for lamps1 foot-warmers1 guards1 and porters4 ,above this lower story a range of offices can be built for the use of the principal officers and staff of the different departments of the company4 ,fig4 #cgd is a plan of a small terminal station on a single line of railway1 where the passenger traffic is small1 and one platform is made to serve alternately both for arrival and departure trains4 ,the booking-hall1 waiting-rooms1 offices1 etc41 are laid down parallel to the line of rails1 and the approach road and footpath are parallel to the building4 ,the platform roof extends to the outer wall1 and provides shelter for the passengers on the platform1 and forms a shed for the carriages at night4 ,fig4 #cge is a sketch of an intermediate or roadside station on a single line of railway4 ,all the offices1 waiting-rooms1 etc41 are on one platform1 which serves for trains travelling in either direction4 ,the dotted lines show the additions which would be necessary to make the station a stopping-place for trains working in opposite directions4 ,fig4 #cgf shows an ordinary intermediate or roadside station on a double line of railway1 with two passenger platforms1 and a connection between them either by subway or over-line footbridge4 ,the principal offices and waiting-rooms are shown on the one side1 and only small waiting-rooms1 etc41 on the other4 ,illustration3 ,fig4 #cgf ,illustration3 ,fig4 #cgg1 #cgh ,illustration3 ,fig4 #cgi1 #chj ,illustration3 ,fig4 #cha1 #chb ,fig4 #cgg is a sketch of a double-line intermediate or roadside station at the junction of a small single-line branch railway4 ,branch-line passengers to and from the main ,,down-line trains merely walk across the platform to get into their respective trains1 and those to or from #beh the main ,,up trains walk across the footbridge or subway to get to the opposite platform4 ,fig4 #cgh is a plan of a double-line roadside station1 with two main-line passenger platforms and a dock line and platform for the use of local or branch-line trains4 ,this arrangement is applicable where the actual junction with the main line is at a little distance from the station1 but not sufficiently far away to warrant an additional junction station as shown in ,fig4 #cgg4 ,fig4 #cgi shows a similar roadside station laid out with a more comprehensive arrangement of dock-lines and platforms4 ,the lines alongside the main passenger platforms are turn-outs from the main-line proper1 and leave the latter free for the passage of fast through trains or goods trains when an ordinary passenger train is standing alongside the platform4 ,in this way a fast non-stopping train can overtake and be sent forward in advance of a slow passenger train4 ,fig4 #chj shows a roadside station with two double platforms1 the inner lines and platforms being reserved for main-line passenger trains1 and the outer lines for branch-line trains4 ,by this arrangement carriages can be quickly transferred from a branch-line train to a main-line train1 and vice vers2 access from the public road1 or from one platform to the other1 can be obtained either by subway or over-line footbridge4 ,fig4 #cha is a sketch plan of an island platform for a double-line roadside station1 near which there are junctions with two branch lines4 ,the ,,up and ,,down main lines run alongside the wide portion of the platform1 and the branch lines run into the two dock platforms4 ,the waiting-rooms1 refreshment-rooms1 etc41 are placed in groups on the wide platform1 spaces being left between the blocks for the convenience of access from side to side4 ,the booking-office and parcels-office are placed alongside the approach road on the higher level4 ,an over-line footbridge extends from the booking-hall to the dock platforms1 terminating with steps on one side and an inclined ramp of #a in #h on the other4 ,in carrying out the above plan for a railway on an embankment1 the access from the booking-hall to the platform would be provided by a subway instead of an over-line footbridge4 ,fig4 #chb shows another form of island platform1 also arranged for ,,up and ,,down main-line trains1 and two branch-line trains4 ,the access is obtained from a public-road over-line bridge crossing the #bei railway1 and the booking-office is placed at the top of an incline1 or ramp1 leading down to the platform4 ,the dock-line platforms are arranged different to those in the preceding example1 with the object of providing longer platforms for the main-line trains4 ,this result1 however1 is obtained at some little inconvenience to the dock-line trains1 as the passengers from one of these must walk round a portion of two platforms to get into the other dock-line train1 instead of merely walking across the platform as in ,fig4 #cha4 ,in some cases of island platforms the total width of the station buildings and platforms is made much greater than indicated in the above sketches1 and a wide1 easy incline constructed from an over-line public-road bridge1 to allow cabs and carriages to come down to a large paved area between the platforms1 for the convenience of setting down and taking up the train passengers and their luggage4 ,the island-platform arrangement possesses many advantages for the exchange of passenger traffic4 ,all the platforms are connected and on one level1 and passengers1 together with their luggage1 can be quickly transferred from one train to another4 ,one set of waiting-rooms1 refreshment-rooms1 etc41 are sufficient1 and are available for the passengers of all the four trains4 ,a smaller number of station men are required for the work1 as the staff can be more concentrated and better utilized than when there are separate platforms on opposite sides of the line4 ,the number1 size1 and arrangement of waiting-rooms and other offices for the public at a large station will depend upon the amount and description of traffic to be dealt with at the particular station under consideration4 ,where the passenger traffic is to a large extent of a local or short distance character1 a moderate amount of waiting-room space may be sufficient1 as these local passengers regulate their arrival so as to avoid waiting any great length of time for the trains4 ,an enormous suburban passenger traffic is carried on in many places with a very limited waiting-room accommodation1 the frequency of the trains and the routine of the travellers reducing the necessity of such rooms to a minimum4 ,a more ample waiting-room space will be necessary when providing for a large1 long journey1 or through traffic1 and for stations at seaports1 as the intending passengers1 particularly those landing from steamers1 generally reach the station a considerable time before the departure of the trains to take them #bfj forward4 ,for this class of traffic it will also be necessary to provide suitable refreshment-rooms4 ,at large terminal stations it is frequently found more convenient for the working of the traffic to have two or more sets of waiting-rooms1 etc41 separating the local and long-journey passengers1 and placing the rooms alongside the corresponding platforms4 ,lavatories and conveniences at large stations should be provided on a liberal scale1 and fitted up in the most substantial and efficient manner4 ,not only should they be thoroughly well ventilated1 but they should have abundance of light4 ,nothing tends so much to ensure order and cleanliness in these places as plenty of light4 ,it will frequently be found that at many of the large important stations there are local surroundings and circumstances of level and foundations1 which will to a great extent influence the arrangement of the rooms and offices to be devoted to the public service4 ,no fixed or standard type could be adopted for all cases4 ,each one will have to be studied out to suit the locality1 and the grouping must be made to work in with the best facilities obtainable4 ,in all such cases one of the principal points is to select a convenient position for the booking-hall1 easy of access to all persons entering the station premises4 ,on no account should the ticket-office be placed in a position tending to block the thoroughfare on to the platforms4 ,a large number of intending passengers may already be in possession of tickets1 and the station arrangements should enable these passengers to proceed at once to the platforms without having to struggle or force their way through crowds of other passengers gathered round the ticket windows4 ,in some instances it is found expedient to provide auxiliary booking-offices for excursion traffic1 to be used only on special occasions1 thus restricting the principal booking-offices to the ordinary main-line booking4 ,when laying out small intermediate or roadside stations for either double or single line1 or small terminal stations on short branch lines in thinly populated districts1 it becomes a question how to provide the requisite statutory accommodation with a minimum amount of building4 ,the following sketches taken from actual examples may be of use for reference4 ,fig4 #chc shows the smallest size of station building that can very well be constructed to be of any practical service4 ,it comprises an office for the station-master1 who has to attend to the tickets1 #bfa parcels1 and telegraph2 a waiting-hall with glazed front2 a small waiting-room and ,w4,c4 for ladies2 and a yard with conveniences for gentlemen1 coal store1 etc4 ,access to the station is obtained through a gateway in the platform fencing4 ,fig4 #chd shows a somewhat similar arrangement1 but with two additional rooms4 ,the road approach to the station is brought alongside and parallel to the building1 and access to the platform is obtained by passing through the booking-hall1 which has a glazed front to the line4 ,fig4 #che gives the particulars of a building containing rather more accommodation than the two preceding examples4 ,fig4 #chf shows a small terminal station for a short branch line where there is a moderate tourist traffic during the season4 ,in addition to the regular station accommodation1 a refreshment-room is added for the convenience of those passengers who have to drive into the country1 or have arrived at the station by road conveyance4 ,the platform roof1 which is extended out over the line of rails1 as shown on the transverse section1 forms a complete covering for the platform1 and serves for a carriage-shed at night4 ,the above sketches merely illustrate types of some small stations suitable for home or colonial lines1 and may be built of stone1 brick1 concrete1 iron1 or timber4 ,for towns of more importance1 the offices and rooms would have to be increased both in number and size4 ,on foreign lines it is customary to provide an office and large hall fitted up with counters for the use of the ,local ,excise ,authorities in the examination of passengers' luggage2 and at some stations one or more rooms have to be set apart for the use of the military authorities4 ,narrow platforms should always be avoided1 especially in front of the offices and waiting-rooms4 ,nothing tends more to check the proper expeditious working of the traffic than a confined space for the movement of the passengers and of the station staff carrying luggage4 ,illustration3 ,fig4 #chc1 #chd1 #che ,illustration3 ,fig4 #chf ,in cases where the traffic will warrant the expenditure1 it will be found an advantage to construct a light roof or verandah over a portion of the platforms of roadside stations4 ,this covering will provide a convenient shelter for the passengers and their luggage1 and prevent the crowding of booking-halls and doorways during inclement weather4 ,in hot countries a verandah or awning of some description on the platforms is an absolute necessity1 and those travellers who have #bfd had any experience of railways under a tropical sun1 will call to mind the celerity with which the passengers seek such welcome shade4 ,a very important item in the construction of a large terminal station is the roof over the lines and platforms4 ,wrought-iron and steel can now be obtained in so many convenient sections1 and at such moderate prices1 that timber-framed roofs1 except for very small spans1 are now rarely used for railway work4 ,the metallic structure is much lighter in appearance and more durable1 besides being less exposed to destruction by fire4 ,the introduction of iron and steel has enabled roofs to be constructed of very much larger spans than would have been prudent to have attempted in timber2 at the same time it must be kept in mind that1 notwithstanding this increased facility of construction1 the cost of a roof per relative area covered increases very rapidly as the span increases4 ,the extent of space to be roofed over in some of our modern terminal stations is so large that the question of roof-spans to be adopted has to be considered very carefully4 ,it has been argued by some that if the area be divided out into small or moderate spans1 the presence of the rows of columns for supporting the roof might preclude the possibility of any future re-location of the lines and platforms except by an entire rearrangement of the roof-work4 ,on the other hand1 it may also be stated that railway engineers have now obtained such a thorough experience of the necessary relative proportions of platforms and carriage-lines for large stations1 as to enable them to lay out these works without any risk of requiring alterations for many years4 ,illustration3 ,fig4 #chg1 #chh1 #chi1 #cij1 #cia1 #cib1 #cic ,illustration3 ,fig4 #cid1 #cie1 #cif1 #cig1 #cih ,illustration3 ,fig4 #cii1 #djj1 #dja1 #djb ,illustration3 ,fig4 #djc1 #djd1 #dje ,illustration3 ,fig4 #djf ,illustration3 ,fig4 #djg1 #djh1 #dji1 #daj ,there are so many descriptions of roof-principals used in railway stations that it would be impossible here to introduce more than a few examples4 ,figs4 #chg to #dje illustrate by diagram sketches a series of types taken from actual practice4 ,fig4 #djf gives more in detail the particulars of the roof-principal of #fj feet span1 ,fig4 #cib4 ,as will be noted from ,fig4 #djf1 the width of #abj feet between the walls is divided into two spans of #fj feet each1 the ends of the principals in the centre of the #abj feet being carried on arched wrought-iron girders of #dh feet span1 supported on strong ornamental cast-iron columns placed at #dh-;foot centres4 ,the rain-water from the large centre gutter is taken down inside the columns and conveyed away to drainage pipes laid down for the purpose4 ,the #fj-;foot principal above described forms a very strong roof1 and is light in cost and #bga maintenance4 ,the weight of ironwork1 both wrought and cast1 in the principals1 arched wrought-iron girders1 cast-iron columns1 centre gutters1 etc41 is only #jea of a ton per square 7of #ajj square feet7 of area covered4 ,for comparison1 the weight of ironwork in the roof1 ,fig4 #djb1 of #aih feet span is #adb ton per square of area covered2 and of the roof1 ,fig4 #djd1 of #baj feet span1 is #bjg tons per square4 ,this increase in weight per square as the spans go on increasing results1 not only in a much larger outlay for original construction1 but entails also a proportionally heavier expenditure for maintenance and painting4 ,the item of painting alone is an expensive one in all iron-roof work1 and must be attended to regularly for the proper protection and appearance of the ironwork4 ,with the smaller spans1 the roof-trusses form very convenient supports for painters' scaffolding or planking1 but with the very large spans the greater height and the form of the roof-principals render specially designed scaffolding and appliances necessary for the painting and repairs4 ,doubtless there is something very attractive about a large span roof1 its bold outline stretching from side to side of a wide covered area imparts an imposing effect which cannot be claimed for smaller or more moderate spans2 but where roofs are constructed for purely utilitarian purposes it becomes a question worthy of grave consideration whether a series of smaller spans would not provide the same practical benefits as would be obtained from one very large span4 ,upon referring to the typical sketch of a terminal station1 ,fig4 #cgc1 it will be seen that the total width from inside to inside of main walls is #bdj feet4 ,the lines and platforms are so arranged that by placing rows of columns at ,a1 ,a1 ,b1 ,b1 and ,c1 ,c1 the entire width may be divided out into four spans of #fj feet2 or1 if preferred1 a row of columns at ,b1 ,b may be adopted1 resulting in two spans of #abj feet1 or the entire width may be included in one large span of #bdj feet4 ,any one of the three arrangements will provide an effectual roof-covering1 and the selection must be decided by the cost or expediency4 ,another way to avoid the introduction of large span-roof principals1 and to preserve the covered area free from intervening columns1 is to erect strong truss-girders extending across at right angles from the main walls4 ,these truss-girders are placed at suitable distances1 and #bgb carry simple roof-principals of convenient spans4 ,in some cases the roof-principals are placed as shown in ,figs4 #djg and #djh1 and in others as in ,fig4 #dji4 ,in another system the roof-principals are incorporated with the main truss-girders1 as in ,fig4 #daj4 ,with the above type of covering the truss-girders take the place of the arched wrought-iron girders and cast-iron columns1 as illustrated in ,fig4 #djf1 but will be more costly1 as may be gathered from the following brief comparison3 ,assuming the area to be covered as #dhj feet long and #ahj feet wide1 then the width of #ahj feet could be divided into three spans of #fj feet each1 or one centre span of #fe feet1 and two of #eg feet #f inches if they would work in more conveniently4 ,with columns at #dh-;foot centres longitudinally1 the three-span arrangement would contain the following3--,twenty cast-iron columns in the two rows1 or twenty-two columns if two columns are placed side by side at the extreme end2 #ifj lineal feet of light arched wrought-iron girders in twenty girders of #dh feet span4 ,on the other hand1 with the truss-girders placed at #dj-;foot centres to suit roof-principals resting on the tops of girders1 as shown in ,fig4 #dji1 or to suit the arrangement shown in ,fig4 #djg1 there would be twelve heavy truss-girders1 each of #ahj feet span1 making a total length of #bafj lineal feet of deep truss-girder work1 exclusive of about another #fj lineal feet1 which would be required for the bearings on the side walls4 ,the successful lighting by day of a large roofed-in station will depend principally upon an appropriate distribution of the glazed portions4 ,with a large span1 and the glass skylights placed near the apex1 the side lines and platforms will be much less efficiently lighted than those near the centre2 and again1 if the glazed parts are only at the sides1 then the centre portion will be rather in the shade4 ,where possible it is better to place the glazed portions and slated portions alternately1 so as to obtain a more uniform light all over the centre area1 somewhat similar to the arrangement shown in ,fig4 #djf4 ,roofs over passenger platforms at roadside stations are made in many types1 the arrangement depending in a great measure upon the width of platform to be covered4 ,in many of the earlier stations the roof was extended across from side to side1 and included the lines of rails as well as the ,,up and ,,down platforms1 a system which was not only costly1 but had the disadvantage that the steam and smoke from passing #bgc trains remained for some time under the roof before it was thoroughly dispersed4 ,the more modern and more economical plan is to put the roof or shelter over the platforms only1 and allow the steam and smoke to pass away into the air4 ,in designing the latter class of roof1 the fewer supporting columns the better1 so as to diminish as far as possible the obstructions on the platforms4 ,where the platform is unavoidably narrow1 the roof may be carried on curved brackets projecting out from the walls4 ,except in tropical countries1 where shade is more acceptable than strong light1 a liberal amount of glass should be provided in these platform roofs4 ,on many of our home railways they are entirely covered with glass1 and the abundance of light is found to be of great assistance in the working of the traffic4 ,figs4 #daa to #dbj are sketches of a few out of the many types of small roofs which have been erected over single and island platforms4 ,goods-sheds4--,the form and dimensions of a goods-shed for any station must be determined by the description and amount of traffic to be transacted at the particular place4 ,with an estimate of the traffic before him1 the engineer must consider the internal arrangement of building most suitable for the bulk of the merchandise to be accommodated4 ,the principal object of the shed is to permit of goods being transferred under cover from or to railway trucks or carts without being exposed to the weather1 and the transfer will be expedited if the arrangements are made the most convenient for the particular class of merchandise presented4 ,for some commodities it is considered preferable to unload direct from the railway trucks into carts1 or vice vers1 and thus have only one handling of the goods4 ,to comply with this method1 the cartway must be made almost down to the same level as the rails1 to allow the carts or drays to be drawn close up alongside the railway trucks1 as shown in ,figs4 #dbg and #dbh4 ,this type of shed implies a constant supply of carts1 so as not to detain the railway trucks1 or necessitate the stacking or storing of goods on the low level floor in the way of carting movements4 ,illustration3 ,fig4 #daa1 #dab1 #dac1 #dad ,illustration3 ,fig4 #dae1 #daf1 #dag1 #dah1 #dai1 #dbj ,illustration3 ,fig4 #dba1 #dbb1 #dbc1 #dbd1 #dbe ,illustration3 ,fig4 #dbf1 #dbg1 #dbh1 #dbi ,for general merchandise in boxes or bales1 a raised loading-bank inside the shed is usually found to be the most convenient arrangement both for loading and unloading4 ,the top of the loading-bank should be a little below the level of the railway-truck floor to give clearance to all truck-doors opening outwards4 ,by means of short portable gangways or landings1 the moderate-sized packages are readily #bgh transferred to or from the trucks1 either by hand or by small two-wheeled trolleys1 the heavier pieces being lifted by cranes4 ,the cartway should run parallel to the rails on the opposite side of the loading-bank1 and may be either inside or outside the building1 according to the importance of the place4 ,when the cartway is inside1 the entire front of the loading-bank is available for cart traffic1 but this advantage entails a considerable increase in the size and cost of the building4 ,when the cartway is outside1 the cart traffic is worked through large doorways placed at suitable distances1 and fitted with projecting roofs or awnings to protect the goods during the loading or unloading4 ,at some of these doorways1 short docks about #aj feet square1 or more1 are formed in the loading-bank1 into which the carts may be set back fairly into the shed for the greater convenience of the transhipment of the goods by hand or crane power4 ,where the stacking space is ample1 the contents of several railway trucks may be discharged on to the loading-bank without any delay in waiting for carts1 and the same railway trucks may be loaded with other goods and dispatched outwards1 or may be taken away empty if the loading-bank is reserved for arriving goods only4 ,where the traffic is large and constant there is an advantage in having separate goods-sheds for the inwards and outwards work4 ,the following diagram sketches will illustrate some of the many types of goods-sheds in use on railways3-- ,fig4 #dba shows a shed suitable for general merchandise at a small roadside station4 ,for economy of construction1 the line of rails and cartway are both placed outside the building4 ,a small goods-office is built at one end1 in which is fixed the pedestal and lever indicator of the cart-weighing machine4 ,the roof is projected outwards over the doorways for the railway trucks and for carts4 ,the railway truck doorways are spaced to correspond to the length of the trucks4 ,a narrow platform1 about #c feet wide1 is formed outside the shed alongside the trucks for the convenience of the men when loading or unloading4 ,fig4 #dbb represents a rather larger shed1 with the line of rails inside the building and cartway outside4 ,with this type the railway trucks are entirely under cover1 and can be unloaded or loaded more conveniently4 ,it has also the additional advantage that the trucks and their contents can be left secure when the shed is locked up at closing time4 ,fig4 #dbc shows a shed with a line of rails down the centre1 and a #bgi loading-bank on each side1 the cartways being outside the building2 one loading-bank is for inwards goods1 and the other for outwards goods4 ,on the arrival of a loaded railway truck1 the door on one side is opened1 and the contents unloaded on to one of the loading-banks4 ,the door is then closed1 and the opposite door opened for loading from the other loading-bank4 ,by this method a railway truck can be unloaded and loaded again without changing its position4 ,fig4 #dbd represents a shed with two lines of rails down the centre and loading-banks on each side1 the cartways being outside the building4 ,one line of rails and corresponding loading-bank is for inwards goods1 and the other line of rails and loading-bank for outwards goods4 ,when the railway trucks on the arriving line are unloaded1 they are either drawn out of the shed and shunted on to the opposite line to be loaded again1 or transferred direct on to the opposite line by turn-tables1 or traversers1 placed at convenient distances between the columns supporting the roof4 ,fig4 #dbe illustrates a shed in which both the line of rails and cartway are placed inside the building4 ,this is no doubt the most convenient type for transfer of general goods1 as all the operations of transhipment are carried on entirely under cover2 but it is the most costly1 on account of the large building and roof area required4 ,fig4 #dbf shows a large double shed similar in general arrangement to the type represented in ,fig4 #dbe1 but with three lines of rails down the centre4 ,the line ,a may be used for inwards goods1 and ,c for outwards4 ,by means of turn-tables1 or traversers1 connecting the three lines at convenient distances in the length of the building1 the unloaded trucks can be transferred on to the far line1 ,c1 for loading again1 or on to the line ,b1 to be drawn away out of the building4 ,the lines ,a and ,c may both be used for inwards traffic1 or both for outwards1 and the line ,b used for taking away or bringing in empty trucks4 ,fig4 #dbg represents a shed with the line of rails and cartway inside the building1 and both very nearly on the same level4 ,this class of shed is often considered the most suitable for fruit1 vegetables1 and certain light goods which require prompt delivery and careful handling4 ,fig4 #dbh shows a form of shed with a raised loading-bank on one side #bhj of a line of rails1 and a cartway on the other4 ,with this arrangement the railway trucks may be loaded or unloaded1 either from the raised loading-bank or direct from carts and drays drawn up alongside the trucks1 according to the description of merchandise presented4 ,fig4 #dbi shows a type of umbrella roof sometimes erected over a narrow loading-bank outside of a goods-shed4 ,it is simple and economical in construction1 and provides good accommodation for loading and unloading under cover packages and goods of secondary importance4 ,the above sketches illustrate some of the many arrangements for goods-sheds1 and can be modified and extended in several ways4 ,the leading dimensions1 widths of loading-banks1 cartways1 and gauge of lines1 will have to be adjusted to suit circumstances4 ,looking at a goods-shed merely as a medium for the convenient transfer of merchandise between the railway and the roadway1 the inference is soon drawn that the removal of the goods into trucks or carts should be effected as speedily as possible1 otherwise a large extent of shed-room will be required for carrying on a moderate amount of work4 ,every effort should be made to clear the goods from the loading-bank as soon as they have been properly unloaded and checked4 ,any laxity in this respect will cause an outcry for increased accommodation1 which a little more energy and careful organization would have prevented4 ,timber plank floors are generally preferred for inside loading-banks4 ,inside cartways should be formed either of granite setts or wooden-block paving2 the latter is better1 being less noisy1 and1 if occasionally sprinkled with sand1 will afford a good foothold for the horses4 ,a macadamized roadway under cover is never satisfactory1 as it is always dry1 and never binds together into a compact even surface4 ,sliding or rolling doors are the best for goods-sheds1 as they are more out of the way1 and under better control during high winds4 ,cranes of appropriate strengths1 and worked by hand or other motive-power1 should be distributed in suitable positions throughout the shed4 ,they should be placed so that they can1 when required1 lift direct out of a railway truck on the one side1 and deposit into a cart or dray on the opposite side of the loading-bank4 ,goods-sheds may be built of stone1 brick1 iron1 or timber1 or a #bha combination of all of them4 ,where the requirements are well proved1 and the traffic certain1 it is better to build a substantial permanent structure4 ,iron sheds1 with sides and roofs of galvanized corrugated iron sheets1 will last for many years if not made of too light materials4 ,there are many cases where it is more prudent to put up a goods-shed in timber than to incur the cost of one of more permanent character4 ,where the traffic is uncertain1 or the foundations bad1 or out in undeveloped districts abroad1 a building of timber will serve the purpose for a number of years1 or until the period of probation has passed1 and the actual requirements are accurately ascertained4 ,in a timber-built shed1 the decay usually commences about the ground line1 but if the nature of the soil will permit of the construction of a small dwarf foundation wall of masonry or concrete up to about nine inches above the ground line1 the life of the building will be prolonged for several years4 ,the best method of admitting daylight into a goods-shed is from the roof1 and a liberal extent of roof-glazing should be provided for the full length of the building1 and so distributed as to be well over the loading-banks4 ,in tropical countries the amount of roof light must be reduced1 on account of the great glare from the sunlight4 ,an ample supply of artificial light will be necessary when working after dark or during the night4 ,in some instances the goods-sheds in large and important business centres have one or more upper storys1 in which goods are warehoused pending the owners' instructions1 the goods being transferred between the loading-banks and upper floors by lifts or cranes4 ,a proper supply of weighing machines for carts1 drays1 railway trucks1 and packages on the loading-banks will be necessary to facilitate the checking of the goods4 ,there is always a large proportion of traffic which can be dealt with outside the goods-sheds1 either on loading-banks or cartways alongside the sidings4 ,outside loading-banks should be of good width1 with approach roads of easy gradient4 ,in tropical countries a light shed1 open on all sides1 is frequently erected over a portion of these outside banks1 to protect the goods and workmen from the heat of the sun4 ,fixed cranes or travelling cranes will be required for lifting the large packages1 heavy castings1 and logs of timber4 ,where there is a large cattle traffic1 separate sidings1 loading-banks1 and approach #bhb roads should be set apart for the purpose1 with suitable water-troughs and cleansing appliances4 ,horses can be unloaded at any loading-bank1 but for the more valuable class of animals and for carriages it is usual to construct a special horse and carriage dock1 as shown in ,fig4 #dcj1 the carriages being wheeled off the end of the carriage truck1 as indicated in the section4 ,cartways alongside the sidings are very convenient for unloading coals1 stone1 bricks1 sand1 lime1 and many other materials which have to be passed out of the trucks in small quantities at a time4 ,to encourage and facilitate traffic at roadside stations1 traders are frequently allowed to stack or store large supplies of some of the above materials on ground set apart for the purpose near some convenient siding1 the stock being disposed of in detail to suit the local requirements4 ,coal-drops are sometimes adopted where there is a large trade in that commodity4 ,they are constructed by carrying the line of rails on strong balks of timber or small girders placed across the top of walled-in coal-yards or divided areas4 ,the coal is thrown out of the trucks1 and falls a depth of #ae or #bj feet into the yard below4 ,in consequence of the height from rail-level to ground a large tonnage can be piled up1 and stored in a small area1 and the unloading of the trucks effected very rapidly1 particularly so where special trucks with opening floors or hinged bottoms are used for the purpose4 ,in many cases capacious roofed-in sheds are built for storing coals1 lime1 cement1 grain1 or other materials liable to deterioration from the weather4 ,these sheds are built alongside a siding2 the contents of the trucks are unloaded or thrown into the sheds through doors spaced to correspond to the railway-truck doors1 and are carted away through doorways on the opposite side4 ,it is customary to place buffer-stops of some form at the termination of dead-end sidings in a station1 to bring to a stand such carriages or waggons as may be approaching with too much speed to be stopped without the interposition of some substantial barrier4 ,figs4 #dcj1 #dca1 #dcb1 and #dcc are sketches of some of the many kinds of buffer-stops1 and will explain themselves4 ,in ,fig4 #dcj the buffer-stop is made of flange rails1 and is shown as fitted in a carriage-dock with wrought-iron plate landing1 ,a1 and plate-iron hinged flaps1 ,b1 ,b4 ,the latter are turned over1 and rest on the floor of the carriage-truck1 to form a pathway when taking on or off a vehicle4 ,illustration3 ,fig4 #dcj1 #dca1 #dcb1 #dcc ,fig4 #dca shows a buffer-stop made of double-head or bull-head rails2 #bhd and ,fig4 #dcb is a buffer-stop made of heavy timbers4 ,fig4 #dcc shows a very simple buffer-stop frequently adopted for sidings where there is not much traffic4 ,it is made of good old sleepers bound together with old double-head rails1 and the interior filled with earth or clay4 ,in addition to the buildings alluded to in the foregoing description1 the engineer has to design and construct very many others in connection with railways4 ,these will include large running-sheds for stabling working locomotives2 sheds for housing carriages2 workshops for building and repairing engines1 carriages1 and waggons2 foundries2 large stores for materials2 offices2 dwelling-houses2 mess-rooms1 etc42 many of them involving questions of difficult foundations1 and nearly all of them requiring special strength and stability to meet the heavy weights and vibrations to which they are subjected4 ,,chapter ,v4 #bhe ,sorting-sidings--,turn-tables--,travers ers--,water-,tanks and ,water-,columns4 ,sorting-sidings4--,on many important long main lines it is necessary to establish special independent sidings for sorting or arranging waggons of merchandise and minerals4 ,where there are only two lines of rails to serve for the ,,up and ,,down service of a heavy passenger and goods traffic1 it is imperative to restrict those lines as much as possible to the actual transit of trains1 and not to block them by unnecessary occupation for shunting purposes4 ,a goods train running a long distance collects waggons from many roadside stations1 and at some of them several waggons will be taken on1 to be forwarded to various and widely distant destinations4 ,the accumulated train comprises waggons which must be divided out into groups1 to be passed on either to distant sections of the same railway system1 or on to neighbouring lines4 ,to avoid interruption to the train-working1 and the delay of complicated shunting operations at the roadside stations1 the waggons are attached just as they are dicked up1 and the work of sorting is allowed to stand over until the train arrives at the place assigned for the purpose4 ,a site for sorting-sidings is generally selected where the ground and gradient are favourable1 and where ample room can be obtained for a large number of short parallel lines1 with space for future extensions4 ,the arrangement that naturally suggests itself is that of a series of fan-shaped sidings leading out of main shunting lines1 separate from the main-traffic lines4 ,in some cases the sorting-sidings are laid down with dead-ends1 as in ,fig4 #dcd1 and in others they are made as through sidings1 connecting at both ends with shunting lines and main-traffic lines1 as in ,fig4 #dce4 ,each of the sidings is usually made sufficiently long to hold a complete train of sorted waggons1 and the number of them will depend upon the number #bhg of sections to be served1 and the amount of waggons to be sorted4 ,sometimes the sidings are laid with a slight falling gradient leading away from the main shunting lines1 to facilitate the running out of the waggons into the respective sidings4 ,illustration3 ,fig4 #dcd1 #dce ,an arriving goods train is first drawn out of the main-traffic lines into one of the shunting lines1 and then handed over to the staff of men in charge of the sorting operations1 who at once mark the waggons according to the number or designation of the particular siding into which they have to be placed4 ,a suitable engine is generally set apart for this work1 and in a very short time the entire train is divided out by one or more waggons at a time1 and distributed into the various sidings1 representing different sections of the line1 or groups to be handed over to neighbouring railways4 ,when one of these sorting-sidings contains a full complement of waggons1 an engine is attached1 and the train despatched to its destination1 leaving the siding clear for another set of waggons4 ,where the trains to be sorted are very numerous1 two or more shunting-engines may be engaged working at the same time on distinct sets of shunting lines and sidings4 ,sometimes it may be expedient to have one lot of sorting-sidings leading off the ,,up line1 and another lot leading off the ,,down line1 to meet the requirements of trains coming and going in both directions4 ,with sidings well laid out1 and fitted with ample facilities1 a well-organized staff can carry out a very large amount of work both expeditiously and economically4 ,there are several of these sorting-sidings stations in operation1 where from one thousand to two thousand waggons are sorted and marshalled into trains every twenty-four hours4 ,the above diagram sketches merely illustrate the general principle of the sorting-sidings1 and may be modified and enlarged in many ways to suit the traffic requirements and local surroundings4 ,turn-tables4--,turn-tables revolving on fixed centres are made of various sizes according to their use for engines1 carriages1 or waggons4 ,the carrying-beams may be made of cast-iron1 wrought-iron1 or steel1 but the latter material is the most suitable for tables of more than #bj feet diameter4 ,for small turn-tables1 cast-iron beams will serve very well1 for although more liable to fracture1 they will not suffer so much from rust and oxidization as wrought-iron or steel4#bhh ,illustration3 ,fig4 #dcf1 #dcg1 #dch1 #dci1 #ddj ,opinions as to the most convenient position and use of turn-tables #bhi have undergone a considerable modification during the past twenty or twenty-five years4 ,circular and semi-circular running-sheds for engines1 as in ,figs4 #dcf and #dcg1 are not so often adopted now as formerly4 ,although compact and accessible in theory1 they possess the one great drawback that when the turn-table in the centre becomes deranged by wear or accident1 none of the engines on the standing-lines inside the building can be taken out until the turn-table is again put into working order4 ,a stock of from twenty to thirty engines might thus be put entirely out of the service for a day or more4 ,this objection is considered to be of so serious a nature that running-sheds are now almost always constructed of rectangular form1 of which ,fig4 #dch is a type4 ,with this description of shed1 the lines of rails are laid down parallel to one another1 and the engine turn-table is placed on a line separate and distinct from those lines forming connections with the shed4 ,where there is a large goods traffic1 an endeavour is generally made to so lay down the goods-sheds and approach lines and sidings1 that the full complement of waggons may be shunted in or out of the shed at one operation4 ,this arrangement1 which dispenses with turn-tables altogether1 admits of the ready removal of a central or far-end waggon1 without the necessity of taking out so many others in front one by one over the turn-table4 ,at the same time1 there are large numbers of these waggon turn-tables in use1 and there are many cases where access to side sheds or detached stores can only be obtained by turn-tables4 ,a goods-shed and lines laid down with turn-tables1 as in ,fig4 #dci1 will always be more tedious and costly to work than one laid down with direct through lines1 as in ,fig4 #ddj4 ,should either of the turn-tables shown on ,fig4 #dci get out of order and become incapable of turning1 then the entire side of the shed controlled by that table will be rendered useless until the defect be remedied4 ,engine turn-tables are rarely made with more than one road on the top4 ,the most modern types generally consist of two strong wrought-iron or steel-plate girders well braced together and securely attached to a middle framework which rests on and revolves round a centre-piece fixed on a solid foundation ,to the ends of the girders are attached #bij large roller wheels which travel round a solid iron or steel roller-path laid down along the circumference4 ,these modern turn-tables are generally worked on the balancing principle1 by bringing the engine and tender to a stand in such a position on the rails that the greater portion of the weight is thrown on to the cup-shaped steel centre1 so that a small force applied to the long outrigged hand-levers at the ends is sufficient to turn one of the heaviest locomotives4 ,figs4 #dda and #ddb give sketch plan and section of one of these steel-plate girder turn-tables1 which has few parts1 and very little to get out of order4 ,the end rollers guide the table when making any portion of a revolution1 and carry such part of the weight as may not be taken up by the centre4 ,a recess is shown in side wall to facilitate the inspection of end rollers4 ,in the earlier forms of engine turn-tables1 the revolving movement was effected by attaching to the upper portion of the girders a strong winch1 which acted upon gearing fixed either to the end rollers1 or direct on to a toothed ring forming part of the roller-path4 ,in cases where the engine turn-table was in constant use1 as in connection with a large running-shed1 the winch was sometimes driven by a small steam-engine to expedite the movement4 ,the great increase in the lengths and weights of modern locomotives has necessitated the removal of many of the old small turn-tables1 and replacing them with others of #de or #ej feet1 or more1 in diameter4 ,illustration3 ,fig4 #dda1 #ddb1 #ddc1 #ddd1 #dde ,an engine turn-table is a costly item in railway requirements1 not only in the girder-work1 but in the large amount of building in the side walls and centre pier1 and an effort is always made to avoid the outlay unless the table can be placed where it may be of permanent use4 ,in the construction of foreign railways1 and in our colonies1 where the lines are opened in sections as the work goes forward1 the temporary arrangement shown in ,fig4 #ddc is frequently used instead of an engine turn-table4 ,the sketch will almost explain itself4 ,on the main line1 ,a1 ,b1 ,c1 ,d1 switches are placed at ,b and ,c1 from which turn out curved lines1 uniting at the switches ,e4 ,an engine proceeding from ,a1 and passing round the curve ,b1 ,e1 ,g1 then round curve ,g1 ,e1 ,c1 and back along main line1 ,d1 ,c1 ,b1 ,a1 will be turned round as efficiently as on a turn-table4 ,the writer has used this arrangement abroad with great advantage4 ,it involves very little work or expense beyond laying down the permanent way1 and so soon as the temporary terminus of the #bib line has been advanced further ahead1 the rails and sleepers can be lifted and used again elsewhere4 ,figs4 #ddd and #dde give sketch plan and section of a waggon turn-table which has been largely adopted4 ,the centre should be securely fixed on a solid foundation of masonry1 brickwork1 or concrete4 ,the deep outer cast-iron ring is made in segments1 properly fitted and bolted together1 and fastened down to the foundation course4 ,the stop-checks are cast on to this outer ring4 ,two roads1 at right angles to each other1 are laid on the turn-table1 so that waggons to or from the goods-shed have only to make one quarter turn of the table4 ,the top is generally covered with either chequered iron plates or timber to give good foothold for the men and horses which have to pass over in moving the waggons4 ,if properly balanced1 the table is easily turned by men pushing at the opposite corners of the waggon1 or by a horse and tail-rope1 or by hydraulic power through a capstan4 ,in many cases of bad or soft foundations these small turn-tables are erected on a strong framework of creosoted timber4 ,carriage turn-tables are now very rarely used4 ,with the old short four-wheeled carriages the moderate-size turn-table was convenient for transferring an extra carriage to or from a spare carriage-line alongside the making-up train at a platform1 but modern carriages are now so much longer1 some of them twice the length1 or more1 than formerly1 that nothing less than an engine turn-table would be large enough for them4 ,sometimes a carriage traverser is used for this station work1 but much more frequently these long carriages are shunted on or off the making-up train by simply running them in or out through the nearest switches and cross-over road4 ,illustration3 ,fig4 #ddf1 #ddg ,fig4 #ddf is a sketch of a carriage-traverser1 of length to suit an ordinary six-wheeled carriage4 ,the length1 however1 may be extended to take on a bogie carriage or any other long carriage4 ,the framing is made of wrought-iron or steel1 well braced together4 ,the carrying wheels1 ,w1 ,w1 run upon rails laid at right angles to the running-line or siding1 and the carriage is moved on to or off the traverser by means of the hinged ramps shown at ,r1 ,r4 ,a carriage1 once on the traverser1 may be moved across one or several lines of running road1 according to the extent of traverser line laid down2 and this appliance is very suitable for large terminal stations and carriage-repair shops4 ,it will be observed that the operations of the #bid turn-table and the traverser are quite distinct4 ,with the former a vehicle can be transferred from one line to another1 and also turned completely round2 but with the traverser the vehicles are simply moved in a parallel direction1 from one line to another1 and when it is necessary to turn or change a vehicle end for end1 as in the case of a mail-bag-catching apparatus van or a special saloon1 then resort must be had to a turn-table4 ,cranes4--,a large portion of the merchandise conveyed on railways must be lifted into or out of the trucks by cranes4 ,the position1 description1 and capacity of these will depend upon the materials to be handled4 ,large slow-working powerful cranes will be necessary for raising heavy castings1 large logs of timber1 or massive blocks of stone2 while the small quick-acting cranes will be more suitable for dealing with the lighter packages1 casks1 and bales4 ,fig4 #ddg shows a gantry or overhead crane1 used for lifting heavy weights out of an ordinary road-waggon1 carrying them a short distance1 and then depositing them in a railway truck1 or vice vers4 ,double-flanged rollers1 attached to the ends of the platform ,c1 ,c1 run upon the rails ,r1 ,r1 which are fixed on the top of the beams ,b1 ,b1 secured to the verticals ,a1 ,a4 ,the working length of the gantry is only limited by the number of the verticals1 and this1 being the fixed portion of the work1 may be extended out to any distance required4 ,the travelling or carrying girders of the platform ,c1 ,c may be made of wrought-iron1 steel1 or timber4 ,they must be strongly framed and braced together as a platform to carry the lifting machinery and weight lifted1 and have convenient gearing for effecting the transverse or side-to-side movement1 as well as a horizontal movement along the line of rails on top of the verticals4 ,where the fixed portion of the gantry is of considerable length1 two or more travelling platforms can be used4 ,in the sketch given above1 the entire gantry is shown as made of timber1 but iron or steel can be equally well adopted1 and continuous masonry or brickwork walls may be built to serve as verticals4 ,illustration3 ,fig4 #ddh1 #ddi1 #dej ,fig4 #ddh is a sketch of a small handy crane for warehouse work2 it is quick in action1 and restricted to weights not exceeding twelve hundredweight4 ,this form of crane may be strengthened to lift still greater loads1 but in doing so the additional size of the parts1 and the corresponding extra labour in working1 detract from its efficiency #bif as a quick-acting crane for light weights4 ,fig4 #ddi shows an ordinary fixed three-ton jib crane1 a very convenient size for general station work4 ,the centre pillar is fixed into a bed of masonry or a solid block of concrete4 ,the jib is of wrought-iron or steel1 those materials being so much more reliable than timber1 and very little more expensive4 ,this crane must be fixed so that in one direction the jib may command the centre of a railway truck1 while in the other it can conveniently raise the packages to or from the carts or loading-bank alongside4 ,in the sketch the crane is shown as placed on the loading-bank1 but it may be placed on the same level as the rails if preferred4 ,cranes of this type and strength are frequently found necessary for the inside work of goods-sheds1 where packages of considerable weight have to be handled4 ,a very similar class of jib-crane is constantly made for lifting weights of five or ten tons or more1 the different parts being made stronger and heavier to correspond to the weights to be raised4 ,fig4 #dej shows a five-ton travelling crane4 ,although more costly1 it has the advantage over a fixed crane that it can be moved about from place to place4 ,it is mounted on a very strong waggon framework1 and provided with springs and spring buffers4 ,instead of moving round a long deep centre1 the jib of the travelling-crane is arranged to work round a bevelled metal roller-path laid down on the platform of the waggon1 and has a heavy counterweight loaded to correspond to its capacity4 ,before commencing to lift any weight strong oak blocks or filling pieces are inserted between the tops of the axle-boxes and the under side of main beams of waggon1 to relieve the springs of the pressure which would arise from the weight lifted4 ,from the four corners of the waggon are suspended chains carrying gripping-hooks to be attached or clipped round the rails4 ,these gripping-hooks1 when firmly secured to the rails1 prevent the crane from tilting over1 as the weight of the waggon and also of the rails and sleepers are brought into play to counteract any tendency to throw the crane off its proper balance4 ,with the larger size travelling cranes1 capable of lifting ten or fifteen tons or more1 outriggers of joist or ,i-iron1 moving in slides1 are run out at right angles on either side1 and can be loaded with bars of iron or other weights to form a counterpoise4 ,a medium-sized travelling-crane is a most useful appliance about a #big railway station2 it has a much greater range of utility than a fixed crane1 but it is not always appreciated as it should be4 ,it merely requires a line of rails laid down parallel to the rails of siding1 and may be placed either on the same level as the siding1 or on the level of the loading-bank4 ,being laid flush with the roadway1 the rails do not present any obstacle to the passage of carts or movement of merchandise4 ,as one waggon on the siding is loaded or unloaded1 the crane can be moved along its own line of rails1 and be put to work at another without the necessity of moving or drawing out any of the railway waggons on the siding4 ,five1 ten1 or twenty1 or more railway waggons can be dealt with in this way1 according to the length of crane-line laid down4 ,the crane can also be readily removed to another part of the station-yard1 or to another station along the line4 ,for stations with an intermittent or spasmodic traffic in heavy timber1 large blocks of stone1 or other unwieldy articles1 a travelling-crane is particularly suitable1 as it will meet all the wants so far as the lifting is concerned1 and when the rush of traffic is over1 it can be easily transferred to some other sphere of usefulness4 ,the crane-siding itself is never very costly1 as the rails are generally old rails taken out of the main line1 and laid on good second-hand sleepers4 ,they have little to do1 and merely form a track for the moving crane4 ,fig4 #dea is a sketch of an ordinary ,goliath crane constructed of timber4 ,the general arrangement and capabilities of this crane are somewhat similar to those of the gantry shown in ,fig4 #ddg4 ,both of them are designed to lift heavy weights1 and move them sideways into1 or out of1 ordinary road waggons1 but the methods of application are different4 ,in the gantry the verticals are permanently fixed1 whereas in the ,goliath the verticals and overhead girders are all attached and braced together1 forming a complete framework which is carried by double flanged rollers running on the lines of rails ,r1 ,r4 ,the winches or gearing for lifting the weights1 or slinging them sideways1 or for propelling the crane forward on the rails1 are attached to the verticals as shown1 and are worked from the ground-level instead of the overhead platform1 as indicated in the gantry4 ,as each ,goliath crane is complete in itself1 there is nothing to prevent two or three of them working at the same time on a long length of crane-line4 ,illustration3 ,fig4 #dea1 #deb ,fig4 #deb shows an ordinary derrick crane1 which1 on account of the #bii large and varying sweep of the jib1 is found very convenient for certain classes of work4 ,it occupies a considerable amount of room1 and its adoption is therefore limited to situations where space is of secondary importance4 ,all the cranes described above are shown as worked by hand-power1 but they may be worked by steam1 hydraulic machinery1 or electricity4 ,manual power will be the most economical where the use of a crane is only occasional1 but it would be too slow and costly where there is constant heavy work4 ,water-tanks4--,a supply of good water forms an important item in railway working1 and ample provision must be made at all principal stations for the requirements of engines and general station purposes4 ,according to the locality1 the water may either be procured from the main of some established waterworks company1 or be pumped from a well1 or forced up from a stream by a ram1 or brought down by gravitation in pipes from a spring or stream at a distance4 ,water thus obtained is conducted into tanks placed at a height of #ah or #bj feet1 or more1 above the level of the rails1 and forms a storage supply from which deliveries can be made at a fair pressure and in large volume4 ,the tanks may be made of cast-iron1 wrought-iron1 or steel1 or even of wood4 ,in the great timber-producing countries abroad1 water-tanks1 some of them of large capacity1 are very frequently made of wood1 the circular or half-cask form being preferred2 but at home1 and on ,european lines generally1 wooden tanks are rarely used except for temporary purposes4 ,cast-iron being less liable to deterioration from rust than wrought-iron or steel1 is much used for water-tanks4 ,illustration3 ,fig4 #dec1 #ded1 #deg1 #dee1 #def1 #dfa1 #dfj1 #dei1 #dfb1 #dfc1 #dfd1 #deh ,figs4 #dec to #deg are sketches of a medium-sized cast-iron water-tank1 to hold about #ghjj gallons4 ,the size may be varied both in length1 width1 and depth1 without in any great measure altering the type4 ,the lower portion1 or tank-house1 may be of stone1 brick1 wood1 or iron framework1 and may be utilized as a pump-room1 store1 or lamp-room4 ,in the sketch given a row of cast-iron girders are placed across the top of the walls of the tank-house1 to carry the tank1 the plate-joints of the latter being made to coincide with the centre lines of the girders4 ,the lower and upper edges of the tank-plates are shown curved in section1 the former for appearance and facility of cleaning1 and the latter to check the tendency of the water rippling or splashing #cja over the sides when disturbed during high winds4 ,the large pipe1 ,a1 is securely bolted at the bottom of the tank1 and forms a shield or funnel through which the supply pipe1 ,b1 passes upwards into the tank4 ,c is an overflow1 or waste pipe1 to carry away any surplus which may find its way into the tank after the water has risen to its fixed maximum height4 ,all the contact surfaces of the cast-iron tank-plates must be accurately chipped or planed1 and fitted to ensure water-tight joints4 ,stay-rods must be placed at frequent intervals1 connecting the vertical or outer plates to the horizontal or floor plates4 ,when required to hold more than #bj1jjj gallons1 it is better to make the tank in two parts1 by placing a permanent plate partition across the middle1 in reality making two separate tanks1 which can be connected or disconnected at will4 ,the double tank arrangement gives additional strength1 and possesses the advantage that the one tank can be emptied and cleaned out while the other remains in service4 ,water-tanks constructed of wrought-iron or steel plates are usually made circular in form1 with vertical sides4 ,the floor-plates must be either carried on small girders1 as in the cast-iron tank1 or be strengthened internally with angle-irons1 tee-irons1 and tie-rods4 ,the rivetting must be well done1 all joints sound and watertight4 ,this class of tank must be kept well painted1 or oxidization will take place very rapidly4 ,the arrangement of inlet1 waste-pipe1 and delivery pipe may be the same as for the cast-iron tank4 ,although frequently seen abroad1 these circular wrought-iron tanks are not often adopted at home4 ,by many the appearance of the circular tank is considered inferior to one of neat rectangular shape1 and the form of the round tower does not lend itself so conveniently for use as a pump-room or store4 ,there may be no practical difficulty in constructing a large circular wooden vat or water-tank1 but there cannot be any great actual economy1 except in those countries where suitable timber is very cheap1 and iron very dear4 ,the wooden tank must be made of selected materials1 and by skilled workmen2 but however carefully constructed it cannot be expected to last so long as an iron tank4 ,in many parts of the ,united ,states of ,america there are excellent examples of the circular wooden tank1 strongly put together1 and covered with a light ornamental roof4 ,numbers of these wooden tanks have been erected there in places where the cost of carriage alone of an iron tank would have been a serious item1 and where suitable timber was fortunately #cjb close at hand4 ,in cases where engines are watered direct from a water-tank1 a simple delivery-valve1 as shown in the sketch 7,fig4 #deh71 will answer the purpose4 ,this valve has to be pulled open by the chain and lever1 ,d1 and when released falls with its own weight1 and is kept closed by the pressure of the water above4 ,the delivery-pipe should not be less than #g or #h inches in diameter1 to accelerate the filling of the tenders4 ,where water has to be delivered to engines at two or more places in a station-yard1 and the supply derived from the same principal tank1 the result may be obtained either by laying down #g or #h-;inch main pipes from the principal tank to separate water-columns1 or by erecting two or more pedestal water-tanks1 similar to ,figs4 #dei to #dfb1 each of which holds a little more than the average quantity for one tender1 and can be fed from the principal tank by a comparatively small pipe of #c or #d inches in diameter4 ,it is simply a question of expense--whether it is cheaper to lay down a long length of #g or #h-;inch main pipe and ordinary water-columns1 or to adopt the small pipes and pedestal tanks4 ,figs4 #dei to #dfb are sketches of a medium-sized pedestal water-tank to hold #abjj gallons4 ,the supporting column must have a very wide base1 bolted down to a solid foundation4 ,the tank itself1 made circular in plan1 is generally constructed of light plates of wrought-iron or steel1 the lower portion or floor of tank being very securely attached to the vertical column4 ,notwithstanding their top-heavy appearance1 these pedestal tanks can be made very firm and steady if enough width be given to the base-plate1 and the tank properly fixed to the column4 ,water is led into these pedestal tanks by a small pipe passing up inside the supporting column1 and the delivery may be effected by a simple valve1 as explained for ,fig4 #deh4 ,fig #dfc shows one type of water column for watering engines4 ,the wide base-plate is bolted down on to a foundation of stonework1 brickwork1 or concrete1 and the main supply pipe 7not less than #g or #h inches in diameter7 is carried up inside the column1 and connected with the screw valve1 ,a1 which regulates the delivery to the tenders4 ,the curved top1 which forms the outlet1 and carries a leather hose1 works on a swivel joint1 and can be swung round1 either to the right or left1 for convenience of supplying engines on one or two standing-lines4 ,the delivery valve can be opened or closed by the #cjc small hand-wheel ,b1 which is conveniently accessible to the man on the tender4 ,on the above sketch 7,fig4 #dfc7 the water column is shown placed at an ordinary normal distance from the rails2 but in cases where there is considerable space between the two lines of rails1 or where a platform intervenes1 the swinging arm may be extended out to the necessary length1 and counterbalanced as shown in ,fig4 #dfd4 ,,chapter ,,vi4 #cjd ,comparative ,weights of some ,types of ,modern ,locomotives4 ,weights of ,locomotive ,engines4--,the demand for higher speeds of passenger trains1 with more conveniences1 luxuries1 and consequent increased weights in the carriages1 has naturally led to greatly increased power and weight of the locomotives devoted to the passenger service4 ,although these engine weights have so largely increased during the past twenty-five years1 there is nothing to indicate that they have yet reached the maximum4 ,the tendency is still to increase1 and will doubtless continue1 so long as the permanent way can be made to sustain such enormous rolling loads4 ,locomotives for goods trains have also increased in power and size1 but perhaps not in the same proportion as those for the passenger service4 ,there is not the same disposition to expedite the transit of goods and minerals1 which do not deteriorate during a long journey4 ,perishable articles1 such as fish1 fruit1 and milk1 are usually conveyed by passenger trains1 or trains set apart specially for the purpose4 ,illustration3 ,fig4 #dfe1 #dff1 #dfg ,the heavier engine doubtless possesses greater tractive power1 but apart from the question of tractive power is the all-important one of steadiness and safety on the rails4 ,a locomotive passing round a curve1 even at a moderate velocity1 produces disturbances in proportion to the capability of the machine to adapt itself to the altered position1 and if both the engine and permanent way are constructed so as to be almost unyielding1 then destructive wear and tear and increased risk of derailment must ensue4 ,the adoption of the four-wheel bogie truck to the locomotives on our home and continental lines--although very slow in coming--has contributed greatly to their improvement1 enabling the weight to be distributed over a longer1 yet more flexible wheel-base1 affording greater facility and comparative safety in traversing curves2 and rolling1 or passing over the rails1 #cjf with as little injurious effect to them as possible4 ,it is strange to find that the four-wheel bogie truck1 originally designed in ,england in the early days of the railway era1 should for so long have met with so little favour on this side of the ,atlantic4 ,the ,americans1 at all times prompt to recognize any appropriate mechanical arrangement1 adopted the bogie truck upon its first introduction into the ,states4 ,they have worked out many improvements in the details1 and upon the thousands of locomotives on their vast network of railways1 the bogie truck1 in one form or another1 has been universally adopted from the beginning4 ,on our home and continental lines1 the modern express locomotive1 with a four-wheel bogie truck in front1 is a much longer vehicle than its predecessors1 and its total weight is distributed over a greater wheel-base2 but the actual weight placed upon the driving-wheels1 or on the coupled wheels1 is now very much in excess of former practice1 and must be taken into consideration when working out the details of girders and cross-girders of under-line bridges4 ,numbers of girder bridges have had to be taken down and replaced with stronger structures1 not for reasons of wear or decay1 but simply because they were incapable of carrying with safety the modern heavy rolling loads4 ,present experience points out the expediency of providing in all new under-line bridges a liberal margin of strength to meet future developments4 ,figs4 #dfe to #dgi are diagram sketches of a few modern types of locomotives1 giving leading dimensions and weights1 and may be found useful for reference when working out the necessary strengths of the various portions of bridge-work4 ,upon comparing some of the principal particulars with those of the earlier class1 it will be noted that in many of the modern types the piston area has been doubled1 the boiler-pressure doubled1 and the weight of the engine doubled also4 ,the engines shown in ,figs4 #dfe and #dfg have great weights placed on the single driving-wheels1 and should only be used where there is a very strong permanent way4 ,with the four-wheel coupled engines1 the weight for adhesion can be distributed between the driving and trailing wheels4 ,illustration3 ,fig4 #dfh1 #dfi1 #dgj ,illustration3 ,fig4 #dga1 #dgb1 #dgc ,fig4 #dgc represents a very excellent type of ,american engine which has been extensively adopted in the ,united ,states for many years4 ,the six coupled wheels distribute the weight over a fairly long wheel-base1 #cji retaining their united weight for adhesion4 ,the four-wheel bogie truck in front forms a valuable path-finder to the engine1 both for passing round curves or on straight line4 ,this class of engine is very serviceable for various kinds of traffic1 and is particularly suitable for lines where the rails and fastenings are comparatively light4 ,in the example shown1 the flanges are turned off the centre pair of coupled wheels2 but for lines where the curves are of small radius1 the flanges may be turned off the leading pair of coupled wheels1 instead of the centre pair1 to reduce the length of rigid wheel-base4 ,this type of engine has latterly been introduced on various ,european and foreign railways1 and recently on the ,highland ,railway of ,scotland1 as shown in ,fig4 #dgj4 ,the writer has had engines of this class under his charge abroad1 and found them to be most useful for heavy passenger and goods-train service4 ,they run very steadily1 are easy on the permanent way1 and light in repairs4 ,as they become better known they will be more appreciated1 and will doubtless before long supersede in many cases the rigid six-wheel-coupled goods engine4 ,the principal objection of any importance that can be raised against them is that on many lines the present engine turn-tables are too small for such long engines2 but it would be far more economical in the long run to enlarge a few turn-tables than to continue the adoption of rigid engines which from their form and arrangement tend to unnecessary wear to themselves and the permanent way4 ,illustration3 ,fig4 #dgd1 #dge1 #dgf ,illustration3 ,fig4 #dgg1 #dgh1 #dgi ,fig4 #dgf shows an average sample of the ordinary six-wheel-coupled goods engine in use on so many of our home railways4 ,where the curves are easy and the permanent way strong1 the drawback of the long rigid wheel-base may not be so apparent2 but for a line abounding in sharp curves1 perhaps no more destructive machine could possibly be devised than the ordinary six-wheel-coupled goods engine4 ,without any flexibility1 forced along with great power1 and too often driven at unnecessary high speeds1 engines of this type have too small a margin of safety when traversing the curved portions of the road4 ,a slight unevenness in the rails1 or a sharp flange on the wheel may supply all that is wanting to cause the engine to leave the track1 and the probability that such risks are more common than is supposed1 is far from satisfactory4 ,the great weight of the engine doubtless tends to keep it on the track1 but the rapid wear of the tyres1 and of the #cab inside of the rail-heads clearly demonstrate the enormous amount of friction and abrasion that takes place4 ,fig4 #dgg represents a type of eight-wheel-coupled engine designed for hauling passenger or goods trains over long lengths of heavy mountain inclines4 ,the engine is a large one in every way1 and of great total weight1 but the weight is distributed over a long wheel-base and without imposing a greater tonnage per pair of wheels than is done in some of the smaller and less powerful engines4 ,the flanges are turned off the leading pair and third pair of coupled wheels reducing the rigid wheel-base for curves to #i feet #h inches4 ,the four-wheel bogie truck in front carries only a moderate weight1 being so close to the coupled wheels4 ,engines of this description require a strong permanent way1 as there is a total weight of #fj tons on the four pairs of coupled wheels standing on a wheel-base of #ae feet #f inches4 ,figs4 #dgh and #dgi are types of tank-engines in use on some of the narrow-gauge 7#c feet7 railways4 ,in general design they are somewhat similar to the modern class of engine on main lines of #d feet #h inches gauge1 with four-wheel bogie truck in front1 and four wheels or six wheels coupled1 but with all the parts and weights smaller1 to suit the narrow gauge and lighter permanent way4 ,the extended use of the bogie truck is an admission of its advantage over the fixed-wheel arrangement1 both for distribution of weight and facility in passing round curves2 but although it is now so largely adopted for engines and carriages on our home and continental railways1 it is somewhat of an anomaly to find it so very rarely used for tenders4 ,in the ,united ,states all the locomotive tenders--and many of them of very large size and weight--are carried on two four-wheel bogie trucks1 and traverse the curves as easily as the engines4 ,on this side of the ,atlantic1 the prevailing custom is to mount the tender on six rigid wheels2 and as many of these tenders weigh as much as from #ce to #dj tons in working order1 and have a rigid wheel-base of #ae feet1 it will be seen at a glance that much unnecessary friction and wear and tear would be avoided by substituting two four-wheel bogie trucks for the fixed wheels4 ,,chapter ,,vii4 #cac ,signals--,interlocking--,block ,telegraph and ,electric ,train ,staff ,instruments4 ,signals4--,railway tradition alleges that on one of the early lines opened for passenger traffic1 the precautions for public safety were considered to have been fulfilled by providing a man on horseback to ride along the track between the rails in the front of the locomotive engine1 to give warning to persons strolling on the line1 and to check the advance of the train when necessary4 ,a very short experience of this method of working proved that the full capabilities of the locomotive could not be obtained from a restricted speed of seven or eight miles an hour1 and a more comprehensive system of signalling had to be devised4 ,by fencing in on both sides of the line1 the public were prevented from making a general highway or promenade along the railway1 and the problem was reduced therefore to the signalling for the trains alone4 ,flags of different colours1 held by flagmen stationed at suitable places1 answered the purpose for a while1 or so long as the authorized running speed did not prevent the train being brought to a stand after sighting a flag warning the engine-driver to stop4 ,as speeds were increased1 a longer or more distant view of signals became imperative1 and tall posts1 or semaphore signals1 were introduced4 ,well-defined blades or discs placed on high posts were easily worked from the ground-level1 and could be seen for long distances1 thus enabling the trains to be controlled or brought to a stand before reaching the signal4 ,the efficiency of the principle once recognized1 improvements and additions were made from time to time1 until we have the simple acting tall semaphore signal so universally in use at the present time4 ,the position of the signal arms or blades in the daylight1 and the colours shown by the lamps at night1 form the code of signals for the proper working of the train service2 and as the signal arms and lamps are both worked simultaneously by the same gearing1 it is only #cad necessary to light the lamps to put the signals in complete condition for night-working4 ,for some years1 when the traffic was small1 with trains at low speeds and at considerable intervals1 one double-arm semaphore signal-post at a station was made to serve for all purposes2 but as the train service became more frequent and more rapid1 it was found that another semaphore or tall post signal1 was necessary to give warning to the engine-driver some distance back before reaching the station or home signal4 ,more particularly was this necessary at those stations where it was not intended that every train should stop4 ,this new signal1 called the distant signal1 very soon came into general use4 ,it was placed at distances varying from #djj to #hjj yards away back from the station or home signal1 and was worked by a long strained wire extending from the distant signal to a ground-lever placed near the home signal1 the levers for these distant signals and home signals being thus near together and under the control of one man4 ,more recently it was found necessary to introduce another important wire-worked signal called a starting signal1 which is placed at the outgoing or departure end of the passenger platforms1 lines1 or station sidings1 to prevent any train or engine starting or proceeding on its journey until such starting signal is lowered to indicate that the line is clear4 ,these simple1 independent1 hand-worked semaphore signals did good service for many years1 but being independent and in no way physically connected with one another at junctions1 or stations1 or with the switches they were intended to control1 it was quite possible for mistakes to arise where everything depended upon the accuracy and prompt decision of the signalman4 ,the possibility that such mistakes could occur1 and the certainty that they actually did occur1 and too often with most disastrous results1 led gradually to the grouping and interlocking of a large number of signal levers and switch levers together in one signal cabin4 ,the advantages of the concentrating and interlocking of signals and switches are twofold4 ,in the first place1 one man in the signal cabin can work and control the levers for a large number of switches and signals1 where formerly several men were required to be located at various places in the station-yard2 but the second1 and by far the most important advantage1 is that with proper interlocking arrangements it is practically impossible to give conflicting signals4 ,with a modern interlocking frame1 and assuming the normal position of #cae all the signals to be at danger1 then before a signal can be lowered for an approaching engine or train all the switches and corresponding signals1 from any lines or sidings connecting with the line to be signalled clear must first be set so as to prevent any engine or train coming out of such connecting lines or switches on to the line to be made clear4 ,in a similar manner1 before the points and signals can be set to permit an engine or train to pass from a siding on to the main line all the necessary signals must first be set to danger to prevent the approach in either direction of any engine or train on the main line about to be occupied4 ,the mechanical arrangements of the interlocking frame are so exact and complete as to effectually prevent any but the proper combination being made4 ,an untrained or inexperienced signalman might inadvertently attempt to pull over a wrong lever1 only to find it securely locked and immovable under the control of other levers4 ,the proper sequence of levers must be made1 and the accurately adjusted mechanism automatically prevents mistakes which formerly occurred with the old hand-worked signals from the oversight or confusion of the signalman4 ,the interlocked switches or points are worked from the signal-cabin by light wrought-iron tubing 7termed rodding7 or channel-shaped iron bars supported on fixed iron rollers1 and the signals by galvanized wires running over light pulleys4 ,modern signals are always weighted at the signal-post1 so that in the event of the breaking of the pulling-wire they will fly back to their normal position of danger4 ,the facility and precision secured by the interlocking machinery enabled other valuable accessories to be introduced for the more complete signalling and protection of train-working4 ,amongst these may be mentioned the facing-point bolt-lock and rocking-bar1 signal-detectors at points1 and throw-off or trap points4 ,with the old-fashioned hand-worked switches the man standing alongside could see whether the sliding-rails were properly closed1 and also when the last vehicle of the train had passed over them2 but when important main-line-facing switches or points are worked by rodding from a signal-cabin some distance away1 it is necessary to have some reliable means to ensure that the sliding-rails are actually brought close home1 and also to prevent the switches being moved again until #caf the entire train has passed over them4 ,a set of switches may be carefully made and work well1 but it is quite possible for some fracture or obstruction1 to intervene and prevent them closing properly4 ,if a train or engine were passing through them in a trailing direction1 as indicated in ,fig4 #cde1 the wheels would most probably force the sliding-rail home1 and no disturbance would arise4 ,if1 however1 the train were coming in the opposite or facing direction1 the chances are that some of the wheels would take one road and some the other1 and cause a derailment4 ,the same casualty would occur if the switches were moved during the passage of the train4 ,to guard against the above contingencies1 the facing-point bolt-lock and rocking-bar have been introduced4 ,the system is applied in various forms1 but the arrangement shown in ,fig4 #dhj will explain the principle generally4 ,a strong casting1 ,a1 is securely bolted to the top of the sleeper carrying the chairs on which rest the point ends of the sliding-rails4 ,this casting has an internal groove or chamber formed for its entire length from ,c to ,d1 as indicated by the dotted lines1 and in which slides the locking-bolt ,b4 ,the point ends of the switch or sliding-rails are connected by the transverse rod ,e1 which is forged into a vertical bar form for that portion of its length1 which passes through the opening1 ,f1 prepared for it in the casting ,a4 ,in this vertical bar a hole or slot is cut to correspond to the exact size of the locking-bolt ,b1 and at a distance to suit the sliding-rails when pulled over to their properly closed position4 ,this locking-bolt1 ,b1 will not pass through the hole in the vertical bar until the sliding-rails are quite close home1 and when once through the hole the sliding-rails cannot be moved until the locking-bar is withdrawn4 ,in some cases two holes or slots are cut in the vertical bar to enable the points to be bolt-locked for both directions4 ,the rocking-bar is designed to prevent the withdrawal of the locking-bolt before all the vehicles have passed over the points4 ,illustration3 ,fig4 #dhj1 #dhc1 #dha1 #dhb ,this rocking-bar consists of an angle iron or tee-iron bar of a length equal to the longest wheel-base of the rolling-stock1 and is carried on short pivoted arms working in cast-iron or wrought-iron brackets secured to the rails as shown in ,fig4 #dha4 ,the pivoted arms have a movement backward or forward1 and when at either the one or the other extremity1 the upper surface of the rocking-bar is sufficiently below #cah the top of the rail to be well clear of the flange of any passing wheel2 but while changing from the one to the other position1 and when the pivoted arms are vertical1 or at half-stroke1 the upper surface of the rocking-bar is about level with the top of the rail1 and right in the pathway of the wheel-flange4 ,it is evident1 therefore1 that when the pivoted arms are set in the forward or backward position1 and one of the wheels of a train or vehicle has passed on to the rail over the rocking-bar1 the latter cannot be changed or raised and pulled over to the opposite extremity so long as any one of the wheels of the train or vehicles remain over the rocking-bar4 ,as the same ground-crank which pulls over the pivoted arms from backward to forward also withdraws the locking-bolt ,b1 the latter is thus held securely in the hole or slot of the transverse rod1 ,e1 until all the wheels of the train have passed off the rocking-bar4 ,the operation of changing the points from one road to another is very simple4 ,by means of the rodding ,g1 worked by a lever in the signal-cabin1 the locking-bolt ,b is first withdrawn from the slot2 the points are then pulled over into the reverse position by the rodding ,h1 and the locking-bolt ,b is again set back into one of the slots by the rodding ,g4 ,sometimes1 for economy1 the points1 bolt-lock1 and rocking-bar1 are all three worked by one lever in the signal-cabin1 and one set of rodding on the ground1 as shown in ,fig4 #dhb2 but the arrangement is neither so perfect nor so secure as that shown in ,fig4 #dhj4 ,where there are two sets of rodding and gearing1 the failure or breaking of either of them prevents the complete combination being made1 and indicates at once to the signalman that something is wrong2 but when there is only one set of rodding a breakage may occur without giving any tangible evidence to the signalman of the defect1 and he may proceed to pull over his signal lever in ignorance that the points have not been properly made and bolted4 ,to avoid an accident taking place from the failure of either rodding or gearing1 the signal-detector has been devised1 so as to prevent the possibility of pulling over the signal wire until the points and locking-bar are both in their proper positions4 ,the signal-detector is applied in several forms2 the one shown in ,figs4 #dhj and #dhc will explain the principle on which its efficacy depends4 ,a transverse rod1 ,i1 attached to the sliding-rail1 extends #cai out beyond the rails1 and is formed into a flat bar or plate1 ,j1 sliding through the guide-holes ,k1 ,k in the casting ,l4 ,short upright levers1 ,m and ,n1 work on trunnions fixed in the casting1 and to ,m and ,n are attached the wires leading from the signal-cabin and continuing on to the signal-posts1 as shown in elevation in ,fig4 #dhc4 ,two slots are cut in the plate ,j to receive the curved arms of the levers ,m and ,n when they are drawn downwards to pull off the corresponding signals4 ,neither of the levers1 ,m or ,n1 can be drawn over unless there is a slot immediately under the curved arm into which it can enter4 ,when there is solid plate under a curved arm1 the short lever cannot be pulled over1 and the signal therefore remains at danger4 ,the slots in the plate ,j are spaced so that one will be brought into position for one of the curved arms1 when the points are close home for the main line1 and the other slot for the other curved arm1 when the points are set for the branch line or siding4 ,the two slots cannot be under the two curved arms at one and the same time1 as one of the signals corresponds to the main line and the other to the branch line or siding4 ,in some forms of signal-detector the transverse rod ,i is joined on to a vertical bar which slides through guide-holes in a casting something similar to the arrangement shown in the casting ,l4 ,longitudinal guide-holes1 parallel to the line of rails1 are made in the casting a little above the transverse rod-bar1 and through the longitudinal guide-holes slide two vertical bars which are attached to1 and form part of1 the wire connections to the two signals4 ,the wire bars have each a small tongue or rectangular fin forged on to the under side of the bar1 and there is one corresponding channel cut in the transverse rod-bar4 ,when the switches are properly closed in one position1 the channel cut of transverse bar will be opposite one of the wire bar fins1 and will allow one of the signals to be pulled over1 but the other wire bar cannot be moved4 ,the closing of the switches in the reverse position moves the channel cut so as to allow the other wire bar to be pulled through1 but as there is only one channel cut in the transverse bar1 only one signal can be pulled over for each position of the switches4 ,illustration3 ,fig4 #dhd1 #dhe1 #dhf1 #dij1 #dia1 #dhg1 #dib1 #dhh1 #dic1 #dif1 #dhi1 #did1 #die1 #dig ,throw-off or trap points1 are introduced to throw an engine or train off the rails of a siding on to the ballast1 and so avoid a collision with any other train which may be standing or passing on the line of rails with which such siding forms a connection4 ,fig4 #dhd is a diagram #cba sketch of the arrangement1 in which the main-line points are indicated by the letter ,a1 and the trap points by the letter ,b2 one series of rodding actuated by one lever in the signal-cabin works both the main-line points and the trap points at the same time and by the same movement4 ,the connections are so made that when the points ,a are set for the passage of trains on the main line1 the trap points ,b are set open to throw off on to the ballast1 as shown in ,fig4 #dhd2 and when the main-line points ,a are set to allow a train to pass from the siding on to the main line1 the trap points ,b are closed1 as shown on ,fig4 #dhe4 ,a disc or other signal1 worked or interlocked with the points1 is placed near ,b to notify the engine-driver when he may pass out of the siding on to the main line2 but should he from any cause proceed before the points are properly set and the corresponding signal given1 his engine would run off at the ends of the rails ,c1 ,c1 and be derailed on to the ballast4 ,the inconvenience caused by such derailment would be trifling compared with what might result from a collision with a train standing or passing on the main line4 ,in some cases the siding is continued onwards for a considerable distance from the trap-point rails ,c1 ,c1 as indicated by the dotted lines ,d ,d1 and terminates with a dead end4 ,when this arrangement can be adopted1 derailment is obviated1 and the engine is brought to a stand by a buffer-stop at the end of siding4 ,on no account should trap points be placed close to the top edge of a high embankment1 or up to the abutment or wing walls of an under-line bridge1 where an engine running through them accidentally might fall down a considerable height1 and cause serious results4 ,all sidings joining on to main lines should be trapped as above described1 and when properly signalled and interlocked in the signal-cabin1 the traffic-working can be carried on with increased facility and security4 ,fig4 #dhf is a sketch of an average sample of an ordinary single-arm wooden signal-post1 with signal-arm1 lamp1 spectacles1 ladder1 and gearing complete for wire connection to signal-cabin4 ,when the arm stands out in the horizontal position1 representing the danger or stop signal1 the red spectacles will be in front of the lamps1 and will show a red light to an approaching train4 ,when the arm is lowered1 as indicated by the dotted lines1 the second spectacle will be in front of the lamps1 and will show either a white or green light 7according to the accepted code7 as an all-right signal for the #cbb train to proceed4 ,for many years a white light was adopted for the all-right signal1 but latterly1 to prevent confusion with other white lights about a station1 there has been an increasing disposition to use a green light as an all-right signal4 ,several railway companies have already effected the change1 and others have arranged to follow their example4 ,the counter-weight ,w keeps the signal-arm to the danger position1 except when it is raised by the pulling over of the signal-wire from the signal-cabin working over the pulley ,p4 ,should the wire break when being pulled1 the weight ,w falls down to the stop-plate1 and the signal-arm rises to danger4 ,the signal-posts may be of wood1 wrought-iron1 steel lattice-work1 or cast-iron4 ,the arms of distant signals should be cut to a fish-tail shape1 as in ,fig4 #dhg1 to distinguish them from other signals4 ,goods-line signals should have a thin sheet-iron ring1 as in ,fig4 #dhh4 ,sometimes purple glass is used instead of red glass for the spectacles of goods signals4 ,letters or numbers may be attached to signal-arms to signify the lines or sidings to which they correspond4 ,special signals are sometimes made with the arm working on a centre pin1 as in ,fig4 #dhi4 ,at junctions or places where two or three signals have to be fixed near together1 it is customary to carry them on a bracket signal-post1 as in ,figs4 #dij and #dia4 ,the former represents the home signals at an ordinary junction1 the taller signal being for the main line and the lower one for the branch line4 ,fig4 #dia shows the home signals at a junction where there is one line turning out of the main line to the left and another to the right4 ,the taller signal in this case also serves for the main line and the two lower signals for the branch lines4 ,in important station-yards1 where there are a large number of lines and sidings running side by side1 it is not always convenient or possible to place the respective signal-posts in suitable positions between the lines4 ,to overcome the difficulty1 the signals are erected on light overhead lattice girders1 as shown in ,fig4 #dib4 ,in some cases1 for want of a better position1 or to obtain a more comprehensive view of the lines and signals1 the signal-cabin is built on lattice girders1 as in ,fig4 #dic4 ,ground or disc signals are fixed at the ground-level1 and are worked in conjunction with trap points or outlet switches from sidings4 ,in some cases they are worked direct by a connecting-rod from the #cbc switches1 and serve merely as indicators to show whether the switches are lying for or against an engine passing out of the siding4 ,in other cases they are worked independently from the signal-cabin by a separate lever and wire connection1 the interlocking being so arranged that the lever working the switches must be pulled over before the lever working the disc signal can be moved4 ,in one type the disc signal is fixed to a short vertical axis1 as shown in ,fig4 #did1 and by means of a cranked arm is made to rotate a quarter of a circle1 so as to exhibit either a stop or advance signal according to the position in which the switches are lying4 ,in another type1 the lamp is fixed1 and the red disc1 with a red glass in the centre1 is made to assume a horizontal or vertical position by a rod and crank1 as shown in ,fig4 #die4 ,a simple arrangement of rodding and rollers for switch connections is shown in ,fig4 #dif1 the number of sets of rodding being determined by the number of connections to be made4 ,fig4 #dig is a rodding compensator1 to compensate or adjust for the difference in length of the rodding arising from variations in the temperature4 ,the compensator may be used either vertically or horizontally1 according to space or circumstances4 ,strong wrought-iron or steel cranks of different angles will be required when changing the direction of the rodding1 or connecting to switches and facing point-locks4 ,they must be firmly secured to strong timber framework well bedded in the ballast4 ,for cranks working switches and bolt-locks1 it is better to use extra long timbers under the rails instead of the ordinary sleepers4 ,cross-pieces can be bolted to the ends of the long timbers1 and the cranks placed practically on the same timbers carrying the permanent way4 ,by this means the rails and cranks can always be maintained in their proper relative positions as to distance1 line1 and level4 ,without a large series of diagrams it would be impossible to adequately describe the extent of signalling and interlocking required at large terminal stations and important roadside stations1 but one or two simple examples may serve to illustrate the general principles4 ,illustration3 ,fig4 #dih1 #dii ,fig4 #dih represents the modern grouping of signals considered necessary at an ordinary double-line junction1 showing all the signals at their normal or danger position4 ,the numbers marked on each indicate the numbers of the levers in the interlocking frame of the #cbe signal-cabin4 ,four distinct sets of trains have to be dealt with at this class of junction1 and the interlocking must be so arranged that when the signals are lowered for the advance of any one train1 no conflicting signals can be given to any other train4 ,assuming a train approaching from ,a1 which has to continue on the main line past ,b on towards ,c1 then the levers in the signal-cabin must first be pulled over to set the points #i and bolt-lock #h in proper position for the main line2 and this operation will release the levers which have to be pulled over to lower the signals #e1 #d1 and #f1 but at the same time will lock1 and prevent the pulling over of the levers or lowering of the signals #b and #a for a train from ,a to ,b and ,d1 or of the signals #ad and #ae for a train from ,d to ,b and ,a4 ,the levers will1 however1 be free to pull over for setting the points #ab and lowering the signals #af1 #ag1 and #ac for a train on the main line from ,c to ,b and ,a4 ,in a similar manner1 assuming a train approaching from ,d1 which has to continue up to the main line at ,b and on towards ,a1 then the lever in the cabin must first be pulled over to set the trailing points #ab in proper position2 and this operation will release the levers which have to be pulled over to lower the signals #ad and #ae1 but at the same time will lock1 and prevent the pulling over of the levers or lowering of the signals #e and #d for a train from ,a to ,b and ,c1 or of the signals #af and #ag for a train from ,c to ,b and ,a4 ,the levers will1 however1 be free to pull over for setting the points #i and bolt-lock #h and lowering the signals #b and #a for the passage of a train on to the branch line from ,a to ,b and ,d4 ,for a train from ,c to ,b and ,a1 the levers #ab1 #af1 #ag1 and #ac would be required1 and these would lock levers #ad and #ae1 and prevent the approach of any train from ,d to ,b1 but they would leave free the levers necessary either for a train from ,a to ,b and ,c1 or for a train from ,a to ,b and ,d1 but only one of them at a time1 the setting of the one series locking the other series4 ,a train from ,a to ,b and ,d would require the proper setting of the points #i1 bolt-lock #h1 and signals #b1 #a1 and #c2 and these would lock #e and #d1 but would leave free the levers necessary either for a train from ,c to ,b and ,a1 or for a train from ,d to ,b and ,a1 but only one of them at a time4 ,the cross-over road from the ,,up to ,,down main line1 near the letter ,b #cbf on sketch1 is only intended for use in case of break-down or accidents1 and the normal position of the points is to lie clear for the passage of trains on the main lines4 ,to use the cross-over road1 the whole of the signals must first be set to danger before the points #g and #g can be opened to permit the passage of an engine or train from the one main line to the other4 ,the starting signals #f and #c should be placed sufficiently far away that the longest passenger or goods train may stand between them and the clearance points at ,g and ,e4 ,these starting signals are of great service to train-working at junctions4 ,supposing a main-line train from ,a arriving at ,b before the section from ,b to ,c was clear1 such train could be brought to a stand at signal #f1 and remain there while another train from ,a was allowed to pass ,b1 and proceed onwards towards ,d2 or a branch-line train from ,a to ,d could be brought to a stand at #c1 to allow a main-line train to proceed onwards from ,a to ,b and ,c4 ,the starting signal #ac should be placed well in advance of the cross-over road to control anything passing from one line to the other4 ,fig4 #dii shows the modern grouping of signals for an ordinary single-line junction4 ,the arrangement is almost practically the same as for the double-line junction shown in ,fig4 #dih1 there being the same four distinct sets of trains to be controlled1 but not any cross-over road4 ,the signal-cabin is placed on the main line1 a little in advance of the facing points1 and a well-fenced-in gangway1 the same height as the engine footplate1 is carried out the proper distance from the rails1 on which the signalman can stand to hand over or receive the train staff from the engine-driver when passing4 ,at stations and places where there are several sidings and lines connecting with the main lines1 at considerable distances apart1 it will be necessary to have two or more signal-cabins placed in suitable positions1 not only for expediting the working of the constant shunting movements1 but also to insure that there is a signal-cabin within the regulation distance of all facing points on the main line4 ,so far as the main line is concerned1 the interlocking of these cabins must be connected1 the one with the other1 by slotting1 or co-acting gearing1 in such manner that the cabin in advance shall always be able to control the cabin in the rear in the lowering of the main-line signals for an approaching train4 ,fig4 #cgf is a diagram sketch of a #cbg typical double-line roadside station with two signal-cabins4 ,the ,,north cabin has to work the signals and points in connection with the goods-shed1 goods-sidings1 and market branch1 and the ,,south cabin1 those in connection with the coal and cattle sidings2 and each of the cabins to work the signals and points of that portion of the main line adjoining its own cabin4 ,for siding working1 each cabin is quite distinct and independent of the other1 but for main-line working the lowering of the signals can only be effected by the joint operation or co-acting of both cabins4 ,assuming a train approaching from ,a to proceed in the direction towards ,b1 then1 before the signalman in the ,,north cabin can lower the ,,up home-signal ,c1 the signalman in the ,,south cabin must first pull over his lever and release the slot which retains the signal ,c at danger1 and in doing so the levers in his own cabin will stand locked1 and prevent the lowering of the signal ,d1 or opening of points ,e to allow access from the sidings to ,,up main line4 ,the cross-over road ,f ,g will also be locked for main line clear4 ,when the slot has been released from signal ,c1 the signalman in ,,north cabin can lower the ,,up home signal ,c1 but before he can pull over the lever for this purpose he must first lock the points ,h1 to prevent access from the sidings to the ,,up main line1 and also the points ,k ,l of the cross-over road1 to keep the main line clear4 ,a similar operation has to be gone through for a train approaching from ,b to proceed in the direction towards ,a1 when the signalman in ,,north cabin must first withdraw the slot from the ,,down home-signal ,m before the signalman in the ,,south cabin can lower that signal4 ,a small automatic disc is placed in the cabin to indicate to the signalman when the slot has been withdrawn by his colleague in the neighbouring cabin1 and for facility of working1 the two cabins are usually placed in communication with each other by telegraph or telephone4 ,at some stations similar to the above1 where there is a very frequent train service1 with several of the trains running through without stopping1 it is the practice to have a second or lower arm to the home signals ,c and ,m1 as shown on the diagram1 these lower arms being only pulled off for through or non-stopping trains1 as an indication to the engine-driver that the line is clear in the section ahead4 ,in addition to the leading signals shown in the sketches1 there #cbh are shunting signals for the movement and marshalling of trains--setting-back signals in connection with the making up of passenger trains2 taking on or off passenger carriages2 or moving out empty passenger carriages2 and many other special signals which become necessary for the working of a large and complicated train service4 ,the above simple diagrams will explain some of the principal requirements to be kept in view when working out signalling arrangements4 ,where the lines and sidings are very numerous1 as at important junctions and large terminal stations1 the signalling becomes very intricate1 and may require three or four cabins1 slotted together in such manner that the necessary co-acting may be insured for the proper controlling of the mainline signals4 ,many of these signal-cabins contain a large number of levers1 some of them having as many as a hundred1 and a few of them two hundred and forty levers1 or more1 all of them so carefully arranged that no conflicting signal can be given4 ,not only has much skill to be exercised in the accurate adjustment of the interlocking machinery1 but much study must be devoted to determine the exact duty of every lever1 for the locking or releasing of other levers4 ,signal-cabins may be built of stone1 brick1 or wood4 ,they should be roomy1 well ventilated1 and have abundance of light4 ,every signal-cabin should be placed in the position from which the signalman can obtain the best view of the signals and points under his charge4 ,the height of the cabin floor will depend upon any obstacles that may intervene between the cabin and the signals1 such as over-line bridges1 station roofs1 buildings1 or other obstructions4 ,sometimes the floor has to be kept as low as five feet above rail-level1 to secure a line of sight under the over-line bridges2 and in others the floor has to be raised twenty1 or even thirty feet above rail-level4 ,illustration3 ,fig4 #ejj1 #ejh1 #eja1 #ejb1 #ejf1 #ejg ,figs4 #ejj1 #eja1 and #ejb show plan1 transverse section1 and elevation of a signal-cabin suitable for a small roadside station4 ,the lower story and chimney-stack are of brick1 and the upper story of wood1 with slated roof4 ,there is room for an interlocking frame of twenty or twenty-five levers1 and space at the end of the cabin for the block-telegraph instruments1 or electric train-staff instruments4 ,the roof-work is open up to the slateboards1 to obtain as much air capacity as possible4 ,in the transverse section a winch for working mechanical gates is shown at the end of the interlocking frame4 ,there #ccj is a liberal amount of glass1 and two or three sliding windows1 which the signalman can open to enable him to speak to the engine-drivers or others during shunting operations4 ,the lower story of the cabin can be utilized for trimming lamps and keeping a small supply of coals and other stores4 ,when working after dark the lamps in the cabins should be well protected by shades1 to prevent the lights being seen by engine-drivers1 and mistaken for signals4 ,interlocking4--,there are several systems of interlocking1 each of them varying considerably in the form and mode of application1 but all of them having the same general object of securing or releasing the necessary levers for each combination of signalling movements4 ,a brief description of one of the systems will explain the order in which the movements have to be made1 and the security which can be obtained by the locking4 ,figs4 #ejc1 #ejd1 and #eje1 are sketches illustrating one of the types of wedge and tappet interlocking4 ,each lever works on a fulcrum or pinion as at ,a1 and has a lower arm ,b for lifting the rods leading off to points or signals1 and an arm ,c to carry a counterweight when necessary4 ,cast-iron braces ,d are placed at convenient distances between the series of levers to carry the top frame ,e on which the lever floor casing ,f is bolted4 ,this casing is continuous from end to end of the locking frame1 with the exception of the narrow openings through which the levers travel when moving backwards or forwards4 ,the sleeve-block ,g1 resting in the depressed portions of the arc1 retains the lever in position4 ,when taking hold of the main lever ,l1 the signalman's hand draws the small side lever ,m1 close to the main lever1 and raises the sleeve-block ,g sufficiently high to pass over the top of arc ,f1 the lever ,l can then be pulled or pushed over1 and the block ,g will fall into the depression at the end of the stroke when the hand is removed4 ,n is a tappet or thin flat bar attached to the main lever1 and which works backwards or forwards between the wedges in the wedge frame ,o4 ,the wedges move horizontally between guide pieces1 and work either singly or are connected by the lower slide bars to other wedges some distance away on the frame according to the position of the levers which have to stand or move in unison for the releasing or locking4 ,a strong cover is placed over the wedge frame to keep out the dirt4 ,illustration3 ,fig4 #ejc1 #ejd1 #eje ,figs4 #ejd and #eje show plan views of four levers in a signal cabin #ccb taken just above the level of the tappets4 ,in ,fig4 #ejd1 all the levers are in their normal or forward position1 with the home and distant signals at danger1 and the facing points leading into loop or siding lying for main line4 ,previous to the approach of a train on the main line1 the home and distant signals have to be lowered1 and will require the pulling over of levers #a and #b2 but these levers cannot of themselves be moved1 as the wedges ,p and ,q are locked by the straight side of lever #c4 ,the operation would therefore be as follows3--points lever #d being set in its normal position for the main line would remain forward1 lever #c working the facing point bolt-lock would be pulled over1 and in doing so would move the wedge ,r to the right into the recess of tappet of lever #d1 locking that lever1 and presenting the recess of its own tappet ready to receive the wedge ,q4 ,lever #b can then be pulled over1 and will move the wedge ,q to the right into the recess of tappet of lever #c1 and present its own recess for wedge ,p4 ,the pulling over of lever #a completes the series1 by moving the wedge ,p over to the right into the recess of tappet of lever #b4 ,fig4 #eje shows the positions of the tappets and wedges with the levers #a1 #b1 and #c1 pulled over to make the combination described4 ,upon examination1 it will be seen that levers #b1 #c1 and #d1 are all securely locked1 the points cannot be moved1 nor the facing point bolt-lock withdrawn1 nor the home signal changed until the lever #a is pushed over again into its normal or danger position4 ,to restore the levers to their forward position1 they must be set back in the reverse order to which they were pulled over4 ,to simplify the explanation1 only four levers are shown in the above sketches1 but the principle is constantly extended out to a very large number of levers1 and in many cases necessitates the introduction of several rows of wedges as indicated by the dotted lines4 ,in some instances a combination is effected by pulling a certain lever only half over4 ,in some systems the preliminary action or spring handle locking is adopted1 in which the locking is actuated by the small side lever1 similar to the one marked ,m on ,fig4 #ejc4 ,the advocates of this arrangement claim increased security and precision in the interlocking1 while on the other hand it is alleged that the mechanism is rendered more complicated without any corresponding advantage4 ,detached ,lock4--,sometimes there is in the vicinity of a railway station1 #ccc a siding which is too far away to be worked direct from a signal cabin1 and not sufficiently used to warrant a separate cabin4 ,such sidings can be worked by a small ground frame opened or locked by a special key attached to the interlocking machinery in the adjoining signal cabin on a double-line railway1 or attached to the train staff on a single line4 ,fig4 #ejf shows the arrangement applied to a double line with the outlying siding turning out of the ,,up main line1 the points lying in a trailing direction for the running trains4 ,before the special and only key can be withdrawn from its seat in the interlocking frame of the signal cabin1 all the ,,up main line signals must be set to danger1 and cannot be moved from danger until the key is restored to its proper seat again4 ,when the key is removed from the signal cabin1 it can be taken to the ground frame at ,a1 inserted in the key opening1 and by turning it partly round1 will release the bar which locks the levers of the facing point bolt-lock and the points4 ,when these two levers are free the points can be opened1 and vehicles moved into or out of the siding ,b ,c1 but the special key cannot be withdrawn from the ground-frame ,a1 until the points and facing point bolt-lock are put back again into their normal position for main line working4 ,when the operations at the siding are completed1 the special key can be removed1 and taken back to its proper place in the signal-cabin1 and ordinary working be resumed4 ,fig4 #ejg shows the application of the detached locks on a single line1 and is a sketch of a portion of railway on which there is a small station ,b1 with a goods siding ,f ,g1 where the traffic is too small to require anything more than ground frames and detached locks4 ,an engine-driver before leaving the station ,a1 receives a train staff1 which gives him possession of the line as far as ,c1 including of course the intermediate station ,b1 and this staff he must carry with him and hand over to the signalman on his arrival at the end of the section at ,c4 ,at each of the points ,d and ,e is placed a two lever ground frame1 similar to the one shown in ,fig4 #ejf1 and attached to the train staff is a key1 which will operate either of the two ground frames1 but only one at a time1 as the key must be inserted before the levers can be moved4 ,when the train is proceeding in the direction from ,a to ,c1 it will be more convenient to shunt vehicles into or out of the siding ,f ,g1 by means of the points ,e1 but when proceeding from ,c to ,a1 the points ,d will be more convenient4 ,whichever of the points #ccd be used1 they must be set1 and bolt locked for the main line before the train staff and its key can be withdrawn from the ground frame and restored to the engine-driver4 ,as the siding is trapped at ,f and ,g1 it is impossible for any vehicles to be moved out on to the main line except through the medium of the train staff and key4 ,the same arrangement of detached lock is equally available for a single siding with only one set of points4 ,electric ,repeater4--,it will sometimes occur that on account of a curve or other obstacle1 the arms and back lights of a distant or other signal cannot be seen from the signal cabin1 and it is necessary to introduce an electric repeater4 ,this little instrument consists of a miniature semaphore signal fixed in a metallic box with a glass front1 and placed on a stand about a foot above the floor level immediately in front of the signal lever for which it is intended to serve as an indicator4 ,like the signal proper1 the normal position of the miniature semaphore is at danger1 but when the signal lever is pulled over in the cabin1 the rod that pulls down the arm on the signal post effects a contact with an electric circuit which lowers the arm of the miniature semaphore at the same moment that the signal arm proper is lowered1 and gives visible indication in the cabin that the signal is working4 ,fig4 #ejh is a sketch of one form of electric repeater4 ,detonators or fog signals are largely used in foggy weather and snowstorms1 when the out-door signals cannot be seen from an approaching train4 ,at such times the atmosphere is so dense1 and the surrounding objects so obscured1 that an engine-driver is totally unable to distinguish the usual landmarks which guide him on the approach to a station or semaphore1 and he might easily pass by a signal unless he received an audible signal to indicate the position of the one that is invisible4 ,detonators are usually made in the form of a circular tin or metallic case about two inches in diameter1 and three eighths of an inch thick1 with soft metal clips on opposite sides for bending over and securing to the rails4 ,the case is filled with detonating powder1 which is crushed by the first wheel passing over it1 and explodes with a loud report4 ,it is customary to use these detonators in pairs placed a short distance apart in case one of them should fail to explode4 ,fog-signalling regulations vary on different railways1 but the #cce arrangements are generally carried out somewhat in the following manner4 ,during the prevalence of a fog or snowstorm1 a fog signalman is placed near each of the signal-posts to be protected1 and is supplied with a hand signal-lamp1 hand-flags1 and a packet of detonators4 ,so long as the arm of the signal-post at which he is alongside stands at danger1 he must keep two detonators on the rail of that line which the signal controls1 and also show a ,,red hand-signal 7hand-flag by day1 and hand-lamp after dark7 to the approaching train4 ,when the signal arm is lowered to show that the line is clear for the passage of the train1 the fog signalman must remove the two detonators1 and show a ,,green hand-signal 7flag1 or lamp7 to the approaching train4 ,when an engine driver hears the report of a detonator crushed by his engine1 it is his duty to shut off steam immediately1 and bring his engine to a stand1 after which he must proceed very cautiously1 until he receives further signals by hand or otherwise1 or receives the line-clear signal to continue on his journey4 ,detonators are also of great service both in fine or bad weather1 in cases of a wash away1 a failure of works1 or obstruction on the line1 when a hand-signal may not be seen1 but a detonator must be heard4 ,mechanical ,gates4--,mechanical gates1 worked and controlled from the inside of a signal-cabin1 are now very largely adopted for public road level-crossings instead of ordinary hand-gates1 opened and closed by a gateman walking from side to side of the line across the rails4 ,being worked from inside the cabin1 they remove all possibility of the gateman being struck by a passing train2 they move simultaneously1 and can be opened or closed in very much less time than hand-worked gates1 which have to be moved one by one1 and being interlocked with the signals1 the mechanical gates cannot be placed across the lines of rails until the train-signals in each direction are set at danger4 ,when set for either train traffic or public road traffic1 the gates are held firmly in position by metal stops1 rising out of cast-iron boxes lying flush with the ground1 and worked by a separate lever in the signal-cabin4 ,assuming the gates to be set for train traffic1 and it is desired to open them for the public road traffic1 the first operation will be to pull over the levers1 and raise the signals in each direction to danger1 and thus release the stop-lever1 which can then be pulled over1 to lower the gate-stops and allow the gate-winch to be turned1 and the gates moved round into correct position4 ,the stop-lever must #ccf then be set back to raise the stops and hold the gates secure4 ,the train-signals will be retained at danger by the interlocking gearing1 and cannot be lowered until the gates are set back again across the public road1 and the gate-stops raised4 ,it is frequently urged that the celerity with which mechanical gates can be swung round and closed across the public road1 is in itself a source of danger1 and that persons preparing to cross the line might be struck by a moving gate1 unless they received a distinct warning that such closing was about to take place4 ,there is no doubt persons have been struck by such gates when closing across the road1 and heavy claims for injuries have been decreed against railway companies1 who were unable to prove that the man in charge had called out or given warning before moving the gates4 ,to ensure that due and undeniable warning shall always be given1 a firm of signal-makers have patented an appliance by which a powerful electric gong1 fixed on the top of a tall post close to the gates1 is sounded automatically by the gate machinery itself1 and before the gates actually commence to move4 ,as previously described1 the pulling over of the lever to lower the gate-stops is the first operation to be performed whenever it is necessary to change the position of the gates1 and it is the pulling over of this lever which actuates the apparatus1 by bringing two electric points into contact1 and thus starting the ringing of the gong or alarm4 ,the gong continues to sound until the gates are moved over1 the gate-stops raised1 and the stop-lever put forward again into its normal position4 ,the arrangement is very simple and very effective1 and being purely automatic must work as regularly as the stop-lever4 ,the tone and volume of the gong can be varied to suit circumstances4 ,the public soon become familiar with its sound1 and recognize its meaning4 ,illustration3 ,fig4 #eji1 #eaj ,figs4 #eji and #eaj give sketch plan and elevation of a set of mechanical gates for a public road level crossing on a double line of railway4 ,the signal-cabin should be placed within a few yards of the gates1 to enable the man in charge to have a good view of the persons and vehicles passing over the roadway4 ,the underground gearing for working the gates and stops1 must be protected by iron or wooden casing4 ,the swinging portion of the wicket gates is closed1 and held by a separate lever4 ,the gates shown on the sketch are for a crossing on the square1 but they can be equally well arranged for an oblique #cch crossing1 and of widths to suit the locality4 ,block-,telegraph ,signalling4--,however complete the outdoor signals and interlocking at any station1 they can only control the movement of trains within their range1 and something more is requisite to ensure the safe working of the traffic over the long lengths of line between stations4 ,for some years a time-interval was allowed for the working of trains following one another on the ,,up and ,,down lines of a double line railway1 no train being allowed to leave a station sooner than a fixed number of minutes after a previous train had started in the same direction4 ,with this system there was always the risk that the first train might be overtaken and ran into by the second1 and especially in the night time1 or when the atmosphere was at all foggy4 ,the electric telegraph was then called in to assist in the train-working1 and brief telegrams were passed between the stations announcing the departure and arrival of trains4 ,the increased security and convenience thus obtained led to the introduction of special electric telegraph instruments1 devoted to the exclusive duty of train-working4 ,these instruments1 termed block telegraph instruments1 are now almost universally used on all double lines of railway1 and have largely contributed to the safe and efficient working of an ever increasing traffic4 ,they are made in various forms1 but the object of each is to ensure that before any train is allowed to start from1 or pass any station1 the signalman at that station shall receive from the signalman in the cabin in advance a distinct visible signal that the line is clear1 and free of any train up to the cabin in advance2 and also that after the train has been despatched1 the signalman in the rear shall be at once advised when the train has arrived at the signal-cabin in advance4 ,fig4 #eaa is a sketch of one type of block-telegraph instrument1 in which the leading feature is the miniature signal-post with its two arms1 an arrangement which readily appeals to the eye of the signalman as being so similar in form and action to the fixed signals in the station4 ,each instrument is supplied with a bell or gong1 by which the adjacent signalmen can communicate with each other1 in accordance with a fixed code of signals which defines the relative numbers of strokes of the bell or gong1 to represent certain regulation calls and answers4 ,in the signal-cabins of the intermediate stations1 two block-telegraph #cci instruments are required1 one for the section of the line to the left hand of the cabin1 and the other for the section to the right4 ,at the terminal stations only one instrument is required4 ,in the instrument shown in ,fig4 #eaa1 the upper arm of the miniature signal-post is coloured ,,red1 and is moved by electricity through the medium of the block telegraph instrument in the signal-cabin in advance2 and until this ,,red signal be lowered to the line clear position by the signalman in the cabin in advance1 no train must be allowed to start from or pass the cabin in the rear4 ,the lower signal-arm coloured ,,white is lowered by the plunger ,a on its own instrument by the signalman in charge1 and at the same moment lowers by electricity the upper or ,,red arm of the block-telegraph instrument in the signal-cabin at the other end of the section4 ,the lower or ,,white arm is thus restricted to the signals sent away from the signal-cabin1 while the upper or ,,red arm is restricted to signals received in the signal-cabin4 ,in the centre there is a round handle ,b1 which rotates a circular disc inside the instrument1 and on this disc are painted three distinct train inscriptions1 only one of which can be seen at a time through the glazed opening4 ,one inscription has the words ,,all ,,clear painted in black letters on a ,,white ground2 another has the words ,,train ,,on ,,line painted in white letters on a ,,red ground2 and the third has the words ,,train ,,off1 ,,but ,,section ,,blocked painted in black letters on a ,,green ground4 ,the instrument is considered to be in its normal position when the ,,green inscription is in view1 and both the miniature signal-arms raised to danger4 ,fig4 #eab represents a portion of double line divided out into sections1 or working blocks1 between the stations ,b1 ,c1 and ,d4 ,each station is provided with the necessary block-telegraph instruments1 and the usual distant1 home1 and starting semaphore signals4 ,illustration3 ,fig4 #eaa1 #eab1 #eac ,fig4 #eac is a diagram sketch showing the pair of instruments as they stand on the instrument-tables in the signal-cabins ,b and ,c1 where ,b#b and ,c#a are the instruments which work together for the block section ,,bc4 ,supposing a ,,down train proceeding from ,a in the direction of ,f1 and approaching the signal-cabin of the block station at ,b1 the ,,down starting signal standing at danger2 then by the code of signals on the bell or gong the signalman at cabin ,b would communicate with the signalman at cabin ,c1 to obtain line clear1 so as to allow the #cda approaching train to proceed on to ,c4 ,if the previous train in the same direction had already passed ,c1 and there was not any obstruction on the line1 the signalman at ,c would give line clear for the ,,down train1 and to do so he would turn his circular disc to show the ,,white inscription ,,all ,,clear1 and then push in the plunger of his ,c#a instrument1 lowering the ,,down or white arm1 ,k1 of his own instrument to the position shown by the dotted lines1 which operation would at the same moment lower by electricity the ,,down or red arm1 ,g1 of the instrument ,b#b in cabin ,b to the position of the dotted lines4 ,the signalman at ,b would then lower his starting signal1 to allow the ,,down train to proceed on towards ,c1 and immediately the train had passed the starting signal he would1 by means of his bell or gong advise the signalman at ,c that the train had entered the section1 or block ,,bc1 and the signalman at ,c would at once turn his circular disc to show the ,,red inscription ,,train ,,on ,,line1 and use his plunger to raise to danger the ,,down or white arm1 ,k1 of his own instrument1 and at the same time raise by electricity the ,,down or red arm1 ,g1 to danger in the instrument ,b#b in cabin ,b4 ,the section ,,bc would then remain blocked until the ,,down train had arrived1 or passed the station ,c1 when the signalman there would1 by means of his bell or gong advise the signalman at ,b that the ,,down train had passed out of the section1 and would turn his circular disc to show the ,,green inscription ,,train ,,off1 ,,but ,,section ,,blocked4 ,both instruments would then be in their normal positions1 with the arms raised to danger1 and ready for further train operations4 ,in a similar manner for the ,,up-line trains on the section or block between ,c and ,b1 the signalman in ,b cabin would turn his circular disc1 and use his plunger to lower the ,,up or white arm1 ,h1 in his own instrument1 ,b#b1 and at the same moment lower by electricity the ,,up or red arm1 ,i1 of the instrument ,c#a in cabin ,c1 the other operation for train on line and train off being carried out for the ,,up train in the same routine as for the ,,down train4 ,the outdoor fixed signals1 or distant home and starting semaphore signals1 have all to be worked to correspond to the block telegraph signals1 and as the latter are always received well in advance of an approaching train1 it follows that when the line is clear1 the outdoor signals can be lowered so as to allow a through or non-stopping train to pass a block-telegraph station at full speed4 ,where the traffic is moderate1 it may be sufficient to have #cdb block-telegraph instruments at each of the stations1 but with a very frequent train service it will be found necessary to divide the line into shorter sections1 and erect signal-cabins and block-telegraph instruments at intermediate points between stations4 ,the code of bell or gong signals is extended to include various matters in connection with the train-working4 ,for example1 when a ,,down train is passing cabin ,b at full speed1 the signalman may observe that there is something wrong--a carriage or waggon on fire1 a tail-lamp missing1 or other irregularity4 ,it is too late to stop the train with his own signals1 but by means of his bell or gong he can call upon the signalman in cabin ,c to stop and examine the train1 and the ,,down distant and home signals at ,c can be raised to danger before the train reaches the cabin at ,c4 ,in every block-telegraph signal-cabin there is a train-book in which the signalman has to write down the time and description of every arriving or passing train1 and1 as this book lies before him1 he has a complete record of the train-working1 with the particulars of the exact times when the line clear signals were given1 and also when the train arrived or passed his signal-cabin4 ,to guard against the possibility of a signalman inadvertently giving line clear1 or allowing another train to pass his cabin before the previous train had reached the signal-cabin in advance1 some railways have adopted the lock and block system4 ,by this arrangement the starting signal at any cabin is electrically and mechanically locked from the cabin in advance1 and can only be released or lowered by the action of the outgoing train itself when passing over a treadle or other appliance connected with the rails of the running-line at the signal-cabin in advance4 ,this method practically gives the train the complete control of the section2 and any signalman attempting1 in error1 to lower his starting signal would find it to remain fixed to danger and immovable1 until released by the arrival of the train at the advance cabin4 ,train-staff for ,single ,line4--,when there is only a single line of railway for both an ,,up and ,,down train-service1 very definite precautions must be adopted to prevent the meeting or collision of trains travelling in opposite directions4 ,where the piece of single #cdc line is short1 and can be worked by one engine in steam1 or two coupled together1 no collision can take place1 as the train-service will be limited to the one train moving backwards and forwards over the section2 but with a long length of single line1 including a large number of stations1 necessitating several trains1 some clear and comprehensive regulations must be introduced4 ,for a long time the simple train-staff was found to give the desired security2 there was only one staff for each pair of adjoining staff-stations1 and no train was authorized to run without the staff1 and as the staff could only be on one train at a time1 the precaution against collisions was looked upon as complete4 ,these staffs1 which were generally made of brass1 or other metal1 were sufficiently large to be conspicuous when placed in the stand prepared for them on the engine4 ,they were lettered to correspond to the stations to which they belonged1 and were made in different patterns to distinguish them for their respective sections4 ,no train was allowed to start from a station until the engine-driver received from the station-master the proper staff to authorize him to proceed to the next station1 and on his arrival there it was the duty of the engine-driver to hand over the train-staff to the stationmaster of that place1 and wait for another train-staff to authorize him to proceed over the next section4 ,so long as the train service could be evenly arranged1 and that there was always an ,,up train to take back a train-staff which has been carried out by a ,,down train1 the simple staff worked most efficiently2 but as the traffic increased1 and two or more trains had to be despatched in the ,,down direction before one had to run in the ,,up direction1 some auxiliary arrangement had to be introduced4 ,this was effected by issuing train tickets1 kept in a locked-up box1 which could only be opened by the key attached to the train-staff4 ,a properly dated train-ticket was handed to the engine-driver of the first ,,down train1 and1 if necessary1 a second train-ticket to the engine-driver of a second ,,down train1 and then the train-staff itself was handed to the engine-driver of the third ,,down train4 ,there were one or two serious drawbacks to this train-staff and ticket-working4 ,as there was only a time interval between the starting of the trains1 the one train might overtake and run into the other with disastrous results4 ,again1 a second or third train1 which was put down in the schedule1 might be withdrawn at the last moment1 and the staff left behind at a station when it was required at the opposite end of the section1 thus causing #cdd much confusion and delay4 ,the ordinary electric telegraph could have been utilized to assist in regulating these train movements1 but it was felt that a mere telegraph message was not sufficient to ensure positive safety1 and that something more tangible was required in the shape of a staff1 or token1 without which no train should be allowed to travel on a single line of railway4 ,to meet this requirement1 the electric train-tablet1 and the electric train-staff instruments have been invented1 each of them being so arranged that upon any one section1 or pair of instruments1 a tablet or train-staff may be taken out from the instrument at either end of the section1 but when once taken out1 no other tablet or train-staff can be withdrawn from either instrument until the first has been delivered and placed again in one or other of the two instruments4 ,figs4 #ead1 #eae1 and #eaf are sketches of an electric train-staff instrument which has been very largely adopted on single lines1 both at home and abroad4 ,in a similar manner to the block-telegraph instruments for double line1 the electric train-staff instruments have each a bell or gong by which the adjacent signalmen can communicate their calls and answers in accordance with a regulation code4 ,in the signal-cabins of the intermediate stations two instruments are required1 one for the staffs belonging to the section to the left of the cabin1 and the other for the staffs of the section to the right4 ,at a terminal station only one instrument is required4 ,illustration3 ,fig4 #ead1 #eaf1 #eae1 #eag ,the head of the instrument contains the electrical and mechanical locking apparatus which controls the withdrawal of a train-staff1 or is acted upon by its insertion4 ,the circular name-plates and pointers1 together with the galvanometer in the centre1 serve as indicators to guide the signalmen in carrying out the various operations4 ,the staffs usually consist of thin steel tubes1 solid at the ends1 with metal rings fixed upon them1 as shown in the sketch1 the number and position of the rings varying according to the section or pair of staff stations to which they belong2 this difference in the rings effectually preventing the possibility of one set of staffs being used or inserted in either of the instruments of the adjoining sections4 ,the staffs rest normally in the long vertical slot ,a1 with the rings fitting in vertical grooves1 which prevent the removal of any staff except by passing it along the curved slot ,,bc1 and out by the opening #cdf ,d1 of large diameter4 ,the electrical and mechanical locking apparatus is placed at the curved slot1 and until the locking-bolt1 which stands across the passage of the curved slot1 be lifted by the joint operations of the signalmen and their instruments at both ends of the section1 no staff can be withdrawn4 ,when the instruments are standing in their normal position of 8staffs in10 the signalmen can arrange between them to withdraw a staff--say either from the ,,north cabin instrument or from the ,,south cabin instrument of the section1 but only from one of them2 and the act of taking out that staff automatically locks both instruments1 and prevents the possibility of taking out any other staff from either instrument until the staff already removed is restored and inserted in one or other of the instruments4 ,from the above description it will be seen that the electric train-staff instrument provides for the safe working of two or more trains proceeding1 one at a time1 in the same direction over a section of single line1 each one being supplied with a train-staff1 which must be handed over at the end of a section before another staff can be issued for a following train4 ,should the train-staffs accumulate in one instrument1 in consequence of more trains running in one direction than another1 a re-distribution of staffs is effected by the authorized persons according to fixed regulations4 ,in the diagram sketch1 ,fig4 #eag1 a piece of single line is shown divided into sections or blocks1 with loops or passing-places at the stations4 ,at the station ,e a train-staff taken out of the instrument ,f serves for the section up to the instrument ,l at the station ,h2 and on the train-staff is a key which will open the detached locks on the points of the small intermediate station1 ,g1 as described in ,fig4 #ejg1 in connection with the working of detached locks4 ,at the station ,h the engine-driver receives another staff from the instrument ,m1 which takes him to the instrument ,n at station ,k1 and in like manner on this staff is a key which will open the detached lock on the colliery siding points at ,i4 ,at stations ,h and ,k are shown loops1 or short pieces of double line1 with platform to enable an ,,up train to cross or pass a ,,down train4 ,the distance apart of the electric train-staff stations will depend greatly upon the number of the trains1 and for a frequent train-service it may be necessary to have the instruments at every station1 whether large or small4 ,the electric train-staff is of great advantage in the working of ballast or construction trains1 as #cdg a staff may be taken out of the instrument ,f at station ,e1 which will give possession of the section as far as station ,h1 and when the ballasting operations--which may be very near to ,e--are completed1 the train can return to ,e1 and deliver the staff again to the instrument ,f1 instead of having to run the entire distance to station ,h4 ,although carrying a train-staff1 the engine-driver must approach stations cautiously1 and obey the fixed signals in the usual manner4 ,,chapter ,,viii4 #cdh ,railways of different ranks--,progressive improvements--,growing tendency for increased speeds1 with corresponding increase in weight of permanent way and rolling-stock--,electricity as a motive-power4 ,looking at railways in their present stage of development1 they appear to be divided into three ranks1 each one distinct from the other as regards its importance1 capability1 and prospects4 ,in the first rank are the great trunk lines1 which1 at home or abroad1 pass through thickly populated districts1 rich in manufactures1 minerals1 or shipping industries1 with their enormous movement of materials and people1 and consequently requiring the most ample works1 equipment1 and appliances for security4 ,in the second rank may be classed those railways which run through ranges of country where the population is moderate1 or where the manufacturing industries are few in number and of minor importance4 ,although of the utmost value to the community of the long series of small towns and agricultural districts through which they pass1 and forming the only great commercial highway1 or connecting link1 with some distant seaport1 or leading business centre1 the traffic returns upon such lines are too small to permit of the introduction of the more complete appliances and luxuries to be met with on the richer railways4 ,in newly opened-out countries1 and in distant colonies1 such lines have often to struggle on for years against financial returns so small as to barely enable them to maintain a condition of efficiency2 but where there are natural advantages in soil and climate1 combined with a judicious development of all the available resources1 the result will be the raising of the standard of the railway itself1 and the enrichment of the entire district through which it passes4 ,when laying out lines of this description1 it may be necessary to curtail as much as possible the expenditure on works and equipment1 but there should be no hesitation in obtaining liberal quantities of land for future enlargement of stations1 or for constructing additional #cdi stations on promising sites4 ,the value of the land may be small in the outset1 but will be enhanced enormously as the benefits of the undertaking become appreciated4 ,in the third rank may be grouped those branch lines which1 starting from a main passenger or goods line1 are laid down to some outlying town1 seaport1 or mining centre1 which1 although small1 is considered of sufficient importance to be brought into railway communication4 ,in general1 these lines are laid to the same gauge as the line with which they connect1 and the transfer of merchandise waggons is readily effected at the point of junction4 ,others1 from motives of economy1 have been laid down to a narrow gauge1 involving the transhipment of all goods and cattle at the station where the break of gauge takes place4 ,most of these branch lines are laid out through the open country1 like an ordinary standard railway1 but with a minimum of works and appliances4 ,others are laid down partly on level public roads1 and partly through the fields1 and are in consequence subject to a statutory low rate of speed when travelling over those portions on the public roads4 ,in many cases the construction of second and third rank railways1 both at home and abroad1 has been largely assisted by state or provincial aid4 ,such assistance must always be valuable to poor or undeveloped districts1 but judgment should be exercised so as not to encourage the introduction of any scheme which would interfere or become competitive with any existing undertaking constructed by public enterprise4 ,so long as capitalists invest their money more from commercial motives than from feelings of philanthropy1 it would1 to say the least1 be unjust and impolitic for any country to adopt a course of competition by national funds1 and so check the flow of public money into public undertakings4 ,ordinary public commercial competition may be business1 as each party can value and compare their own prospects2 but the competition of a scheme enjoying national aid and free money grants is very apt to become one-sided4 ,there is every indication that even what may be termed a fourth-rank type of railway is destined to play a very important part in the industrial enterprises of many countries1 and that in the form of little lines1 made to any convenient gauge1 and laid either along public roads or open country1 or both1 the produce from isolated manufactories1 forests1 quarries1 and large farms will be conveyed to #cej the nearest railway stations with greater facility and at much less expense than by carting along the public highway4 ,such little lines are available in places where the most sanguine promoter would hesitate to suggest an ordinary railway1 and may be found to supply what is felt to be the missing link in the economical transport of a long list of materials of everyday use4 ,as they would be almost exclusively intended for merchandise purposes1 the statutory requirements would be on the most moderate scale1 and as they would be generally constructed at the cost of the parties who had to operate them1 the outlay would be restricted to the actual works necessary for convenience and efficiency4 ,similar little lines have been in use for many years in the busy yards of large ironworks1 shipbuilders1 and many other localities1 where weighty masses of materials have to be moved from place to place in the course of manufacture1 and it would be merely carrying out the same idea to a more extended range4 ,the principal inducement for their introduction is the great advantage1 both in convenience and cost1 that is obtained by hauling a ton of materials over a pair of rails as compared with carting the same weight along an ordinary road2 and as the fact becomes more and more proved by experience1 these little fourth-rank lines will become more general4 ,numbers of them are in use at the present time1 and some of them1 even of only #b-;feet gauge1 are doing good service1 the little trucks conveying manufactured goods to the nearest railway station and returning loaded with coals and other materials4 ,by making suitable arrangements for passing places and junctions1 the system could be carried out to considerable distances in thinly populated districts1 and be made available by means of local sidings1 to several places along the route4 ,with a narrow-gauge type there would1 of course1 always be the time and expense of transhipment to or from the ordinary railway trucks in the same way as with the road carts1 but the time and expense may be lessened by so constructing the little narrow-gauge trucks that the bodies may be readily lifted off the frames and wheels1 and be placed like packing-cases in the railway waggons4 ,it is natural to look to the railways of the first rank for the latest advances in construction1 appliances1 and equipment1 and it is generally there they are found4 ,great trunk lines1 crowded with traffic of all kinds1 have not only the opportunity and means1 but all the strong inducements to try or adopt any arrangement which promises #cea greater facilities for dealing with the ever-increasing demands made on their carrying powers4 ,passenger and goods traffic are so dissimilar in their requirements that when both of them are steadily increasing it becomes difficult1 if not impossible1 to work the two classes over an ordinary double line4 ,in some cases much assistance has been obtained by shortening the lengths of the working sections and introducing intermediate electric telegraph block stations between the ordinary stations4 ,long refuge-sidings have also been introduced at many of the signal-cabins or stations1 into which goods trains can be shunted out of the way to allow fast passenger trains to pass through without stopping4 ,up to a certain extent this arrangement works fairly well1 but where there is a very frequent service of fast and slow passenger trains1 combined with a heavy and constant service of goods and mineral trains1 the two lines of way are practically incapable of accommodating such a number of mixed trains without causing serious detentions4 ,the goods trains must shunt out of the way some time before a passenger train is due1 and this frequent shunting into sidings results in hours of delay in the transit of the goods and cattle traffic2 and when one of such trains is allowed to proceed again on its way up to another station1 dove-tailed as it may be between two fast passenger trains1 there is always the tendency to run at a much higher rate of speed than is prudent for the class of rolling-stock of which the goods train is composed4 ,to overcome this difficulty some railways have introduced additional ,,up and ,,down lines on the busiest part of their system1 making four lines of way in all1 two of these being reserved for the fast passenger and through trains1 and the other two for slow trains1 goods1 and mineral trains4 ,this arrangement of the four lines has afforded great relief to the traffic of all kinds1 and has enabled the service to be worked with much greater facility and punctuality4 ,the goods trains being restricted to their own separate lines1 can proceed regularly in their order1 at their uniform working speed1 without having to resort to the spasmodic fast running too often expected from them when passing over some parts of an ordinary double line4 ,doubtless this four-line system1 or rather the principle of laying down two additional lines of way1 will go on extending1 and will be accelerated in its accomplishment by the growing demand for still higher speed of our fast passenger trains1 and still longer distances to be traversed without stopping4 ,high-speed long-distance through #ceb trains can only perform their journeys with punctuality1 when the route is kept clear of all other trains or obstructions which might interfere with their free running4 ,any check or stoppage in their course would cause loss of time and prestige4 ,it is to be regretted that in so many of the cases where two additional lines of way have been laid down1 more space was not left between the sets of rails for the fast traffic and those for the slow4 ,in many instances the dividing space is not more than #g or #h feet4 ,it would have been better and safer if it could have been made #bj feet4 ,an ordinary goods train is made up of several kinds of trucks1 some empty1 some loaded1 many of them unequally loaded1 all of them subject to heavy work and rough handling1 and more likely to give trouble than the higher class vehicle1 the passenger carriage4 ,the breaking down or derailment of one or two goods trucks on a line of rails close alongside the fast passenger rails1 would in all probability so foul and obstruct the passenger line as to cause a very serious accident to an express train which could not be stopped in time4 ,the greater width would not only provide more clearance in case of breakdowns1 but would afford increased safety to the platelayers and other workmen engaged on the line4 ,the permanent-way men have to be very watchful to keep out of danger on an ordinary busy double line1 but they must be very much more on the alert where there are four lines of way close together side by side4 ,in the neighbourhood of large cities and important manufacturing centres1 railways have created a distinct traffic for themselves by providing means for a large portion of the population to reside in convenient suburbs4 ,local trains running at suitable business hours have induced people of all classes to select homes a few miles away from town1 and the gradual growth of this suburban traffic has produced its own advantages and requirements4 ,at the large terminal stations platform after platform has been added to accommodate the increased number of trains which arrive in the busy parts of the morning or depart in the evening4 ,every facility has to be provided to permit of the expeditious ingress and egress of the large crowds forming the respective trains--ample platforms1 over-line foot-bridges1 subways1 convenient booking-offices1 waiting-rooms1 and left-luggage rooms4 ,the enormous train service on some of these first-rank lines demands #cec the highest efficiency in the signalling and interlocking arrangements1 and the use of any devices which will ensure increased facility and safety in the working of the traffic4 ,with a crowd of trains passing a signal-cabin in both directions1 and often over four lines of way1 it is quite possible for a signalman to make a mistake which cannot be rectified in time to prevent an accident4 ,to obtain increased security many railways have adopted the lock and block system previously described1 or some adaptation of the same principle1 and this method of working will go on extending as the traffic increases4 ,these additional appliances entail additional care and inspection1 for although automatical machinery may be exempt from the human frailty of preoccupation of mind or forgetfulness1 it is somewhat delicate in its organization1 and requires constant supervision to maintain its efficiency4 ,on many of the large lines1 much has been done to give improved carriage accommodation4 ,carriages have been made longer1 easier on the road1 loftier1 better furnished1 and better lighted2 but there is still a very great deficiency in those conveniences so essentially necessary1 especially on trains running long distances without stopping4 ,drawing-room cars and dining-room cars are no doubt attractive1 and may contribute considerably to the popularity of certain routes2 but it is questionable whether many of the lines at home and abroad which have adopted such luxuries1 have not in doing so commenced at the wrong end1 and whether it would not have been more to the public satisfaction to have begun by first providing those conveniences which are found in every carriage on every line in the ,united ,states4 ,it is satisfactory to find that there is a steadily growing tendency to so construct passenger carriages that their occupants may1 by passages or corridors1 communicate with all parts of the same carriage or with the adjoining carriages2 and there is every reason to assume that the carriage of the future1 either by legislation or consent1 will combine both the items of conveniences and intercommunication1 and will confer not only greater comfort to the passengers1 but also increased protection against those outrages which1 unfortunately1 too frequently occur under the system of isolated compartments4 ,it will be instructive to watch the results of the passenger receipts #ced on those lines where only first and third-class carriages are used4 ,the elimination of the second class may at first sight appear an innovation2 but if there is not any pecuniary loss sustained1 there must be a gain in the reduction of unoccupied seats to be hauled4 ,it is customary to provide in every train a liberal number of spare seats of each class to meet contingencies2 and the omission of one class may mean the saving of two or three carriages--a very important item in locomotive power4 ,on important through lines high-speed running has become a leading feature1 and compels a very efficient standard of perfection in works and rolling-stock to effect its attainment4 ,there is no indication of remaining contented with what has been already accomplished2 on the contrary1 the spirit of restlessness is always urging to do something more4 ,the travelling public speak as calmly now of a speed of seventy miles an hour as they did of thirty-five a few years ago2 they thoroughly recognize the value of railways1 and they merely desire to travel still faster4 ,the incentives of emulation and competition are ever present to encourage further and further reduction of the running time1 and the railway that offers a special fast through service for some of its passenger and mail trains1 reasonably expects its popularity and patronage to be in the ascendant4 ,much has been done in permanent way and equipment to make the present high speeds possible1 but more will be required if the speeds are to go on increasing4 ,the passenger carriages for such work must be very substantial1 and naturally heavy4 ,the locomotives to haul a long train must have increased power and weight1 and will necessitate stronger rails to carry the greater rolling loads4 ,with the present system of motive-power1 the heaviest item is the locomotive1 and its weight must always determine and regulate the character of the works and permanent way4 ,rails weighing #ij pounds per yard are becoming common1 and there is clear indication that before very long sections weighing from #ajj to #abj pounds1 or more1 per yard will be brought into use on many lines4 ,there will be no difficulty in making a permanent way strong enough for rolling loads very far in excess of anything in the present practice2 but it will be costly1 and the extra expense per mile1 extended over a few hundred miles1 will represent a sum so large as to raise the question in many cases whether the probable advantages and additional remuneration to be obtained will warrant the outlay4 ,to some extent the increased speed may be attained by dividing the #cee present long trains into two shorter trains1 with a fair interval of time between them4 ,there are many splendid locomotives now running1 which on a fairly level line can reach a speed of considerably over seventy miles an hour with a short train1 but would be quite incapable of doing so with a long train4 ,at the same time it is possible that if passengers increase in the same proportion as the inducements provided1 the short train might not be sufficient for the numbers presented1 and there would be no other alternative but to resort to still greater rolling loads and stronger hauling power4 ,perhaps electricity1 which has already achieved so many marvels1 is destined to take a still more prominent part as a motive-power in the working of ordinary railways1 and may help out of the difficulty by inaugurating still higher speeds without the necessity of incurring stronger works or heavier permanent way4 ,in addition to its success in the telegraph1 in the telephone1 and in its brilliant light1 electricity is every day coming more and more to the front as a motive-power4 ,at present many tramways and short lines1 some of them in tunnel1 some above ground1 and many of them with very steep gradients1 are successfully worked by electricity2 but these1 being of modern construction1 were specially designed and equipped for that method of working1 and none of them as yet resort to high speeds4 ,such rapid strides have1 however1 been already made in the progress of this system of haulage1 as to promise that both increased power and speed will be forthcoming when the demand for them is made manifest4 ,various modes of application are being tried3 overhead wires1 underground wires1 conductors on the level with the rails1 storage batteries or accumulators1 and self-contained electric motors1 each and all of them being carefully tested to ascertain the comparative cost and efficiency4 ,much will depend upon the localities and advantages to be obtained for the respective generating stations4 ,in places where a large1 constant1 and unutilized water supply is available1 a great saving may be effected in the most expensive item of electric working1 but in the greater number of cases steam-power will have to be adopted for driving the generating machinery4 ,the main question will be whether electricity in its most approved form of application can haul a ton of paying load for one mile at a less average cost1 and at as great or greater speed than the ordinary locomotive4 ,until there is #cef very clear evidence that electricity is cheaper1 there will not be any great inducement for its general use as a motive-power on ordinary railways4 ,experiments have been made on some existing railways to ascertain how far this new motive-power can be made serviceable under special circumstances4 ,in one case1 a powerful electric motor-car has been introduced for working frequent and heavy trains through a long tunnel1 where the atmosphere with ordinary steam locomotives became foul almost to suffocation1 and the result has shown that the traffic can be hauled efficiently by electricity1 and the air in the tunnel maintained pure and clear4 ,in this instance1 the question of cost was of secondary importance1 the primary object being to avoid the asphyxiating gases emitted from the ordinary locomotives4 ,in other cases1 specially designed electric motor-cars have been constructed with a view to obtain a higher speed for passenger trains than is at present attained with the locomotives1 and the trials made have proved that these cars could reach a high speed1 but so far only with limited loads4 ,experiments are still going on with larger and improved machines1 from which it is expected to obtain both high speed and much increased hauling power4 ,it is more than probable that amongst the earliest practical applications of electric motive-power on existing railways will be its introduction as an auxiliary on the steep gradients of some of the mountain railways abroad4 ,in many of these regions there are millions of gallons of water running to waste down the ravines1 a portion of which could be utilized in working powerful generating plant1 to drive strong electric motor-cars for assisting the ordinary locomotives up the steep inclines4 ,in such localities1 with free water-power1 the cost of the electricity would be at a minimum1 while the cost of the ordinary locomotive would be at a maximum4 ,in whatever form the electric motor-car may be designed1 we are brought face to face with the old axiom1 that there must be a certain amount of weight to obtain a certain amount of adhesion2 but there will be one important point in favour of the motor-car1 that whereas in the ordinary locomotive the weight for traction can only be distributed over a few working wheels1 the electric arrangement may distribute it over a much greater number1 and so diminish the insistent weight of each wheel upon the rails4 ,there would also be the #ceg saving of the dead weight of the tender1 the fuel1 water1 and other minor accessories1 as well as the advantage that the active power would be applied in a rotary form instead of reciprocating4 ,there are important interests at stake in the perfecting of this new system of haulage1 and day by day new developments are being made to add to its efficiency and reduce its cost4 ,existing railways will1 however1 naturally require some very convincing proof of the all-round superiority of electricity before adopting that power generally in place of their present locomotives4 ,the latter1 with their corresponding workshops and appliances1 represent so large an amount of invested capital1 as to demand most thorough trials and investigation of the new power before they are superseded2 nevertheless1 if further experience proves that electrical power is better and cheaper than the ordinary steam locomotives1 then the change will undoubtedly be made4 ,under whatever system of haulage the acceleration of trains be obtained1 the increased speed will call for increased precautions in the selection and proving of the materials to be used in such service4 ,rails must be made more uniform in quality1 and must be free from the imputation of fracture under regular wear4 ,notwithstanding the great improvements made in the preparation of the steel1 and in the rolling1 there are still far too many steel rails which break under traffic to allow rail-makers to rest satisfied with their work4 ,something is still wanting in the manufacture to effectually remove this disposition to fracture4 ,the safe rail1 the rail of the future1 must be one that may bend and may wear1 but will never break under ordinary use in the road4 ,axles must be stronger and tougher1 as they will have to bear greater torsional strains than are now imposed upon them2 and the wheels1 of whatever type they are made1 must be incapable of collapsing or falling to pieces upon the sudden and severe application of the brake-blocks4 ,a train1 rushing along at a speed of #gj or #hj miles an hour1 may on an emergency have to be brought to a stand in the shortest distance possible1 and the failure of either axles or wheels in the endeavour to avert one form of accident would inevitably initiate another4 ,to permit of unchecked high-speed running1 many sharp curves will have to be flattened1 bridges will have to be built at busy level crossings2 and points1 crossings1 and junctions on the main lines will #ceh have to be reduced to the smallest possible number4 ,it would be difficult to form an opinion as to how far passenger traffic will go on expanding1 but if it continues to increase at the same rate as at present1 some railways may find it expedient1 and even absolutely necessary1 to construct new lines altogether separate and apart from the existing routes1 and for the sole use of their fast through traffic4 ,as roadside or intermediate traffic would not form any part of the scheme1 such lines could be laid out so as to keep away from the populous districts1 where property would be costly1 and pass instead through those parts of the open country where the most direct course and easiest gradients could be obtained4 ,stations would only be required at the very large and important places1 and at long distances from each other4 ,lines of this description1 reserved for through traffic only1 taken alone1 might not pay1 but taken in conjunction with the existing lines1 of which they would form a part1 they might prove to be the best solution of the problem of dealing with a crowded train service1 the remunerative earnings of which1 placed together1 might yield a rich return over the entire system4 ,a project for a separate through line might at first appear a little startling1 but we have well-known precedents in the vast expenditure already incurred in the constructing of enormous viaducts and connecting lines to avoid long detours on certain through routes4 ,the widening out of an ordinary double line into a four-line road was at first considered as a rather venturesome departure2 and it must always be costly because1 in addition to the earthworks and permanent way1 there is the doubling of all the over and under bridges and waterways1 besides the great and expensive alterations at stations4 ,practically it is almost like making a second railway1 and yet the constant extension of the principle is an admission that the working results have proved satisfactory1 in spite of the large outlay4 ,a little later the question will force itself more prominently into notice1 whether the four-line track or the separate fast through traffic lines1 will best answer the purpose4 ,the former possesses certain advantages1 but the latter would give more freedom for high-speed running4 ,engineers have brought railways to their present stage of perfection1 and the public will expect them to devise and carry out still further improvements as the march of development moves onward4 ,it is a simple #cei matter to arrange the traffic on a railway when all the works and appliances are appropriate for the service to be performed2 but the advances which are made follow one another so rapidly as to necessitate constant study and organization to effect the structural alterations and additions requisite to maintain an up-to-date standard of efficiency4 ,the traffic manager on a railway receives his instructions from the directors or controllers of the company as to the working out of the train service1 rates1 charges1 and other items of his department1 but the engineer has to stand alone1 and his technical knowledge and professional skill must enable him not only to design and construct works suitable in character1 extent1 and strength to the duty for which they are intended1 but also to decide when structures are no longer capable of properly sustaining the increasing loads brought upon them1 and must be taken down and replaced with others of a stronger description4 ,for this reason the engineer must carefully consider every circumstance and local feature which may influence the design to be prepared2 he must thoroughly investigate the nature of the ground for foundations1 as the description when ascertained will frequently determine the class of work to be erected1 whether in viaducts1 bridges1 or buildings2 and in his selection of materials and calculations for strength1 he must allow ample margin to meet further increased weights1 as well as for natural deterioration4 ,he should1 indeed1 go a little further1 and as his perceptive ability and training will always enable him the more readily to foreshadow the direction in which improvements or changes are tending1 he should study out and be prepared with his schemes to meet the new departures as the requirements gradually arise4 ,strength and efficiency are the leading points which must be always kept in view1 and the engineer must never forget that he is solely responsible for the safety of the line and works1 and of the public passing over the same4 ,,index #cfa ,a ,accommodation works1 #ab ,air-lock1 #aai ,air-pump1 #abj ,allowances for sinkage on embankments1 #gj ,alteration of gradients1 #ab ---- of roads1 #f1 #aj ,american hand-brake1 #df ,analysis of steel rails1 #aic ,approach roads to stations1 #bdi ,arch culverts1 #gf ,automatical gate-alarm1 #ccf ,b ,ballast1 #bbe ,bascule bridge1 #he ,battering-rule1 #gb ,bearing-weights of various materials1 #abi ,beater1 #bci ,bench marks1 #ff ,bissell truck1 #eh ,block crossing1 cast steel1 #bce ---- telegraph signalling1 #ah1 #cch ,board of ,trade requirements1 #ah ,bog-cutting1 #fe ,bogie carriage1 #ed ---- engine1 #ef1 #cjf ,booking-hall1 #bdi1 #bfj ,book of reference1 #h ,borings for foundations1 #abi ---- for tunnel work1 #afd ,borrowed earthwork1 #fa ,bottom-pitching1 #bbe ,bracket signals1 #bj1 #cbb ,brake-power on gradients1 #de ,brakes for goods waggons1 #df ,brick-well foundations1 #abc ,bridges1 #gi ---- over public roads1 #aj ,broken stone ballast1 #bbe ,buffer-stops1 #bhb ,bull-head rail1 #aia ,c ,cab-rank1 #bea ,caisson foundations1 #aba ,cant of rail1 #bcj ,carriage accommodation1 #cec ---- bogie1 #ed ---- dock1 #bhb ---- traverser1 #bib ,cast-iron column piers1 #ig ---- in bridges1 #bg ---- saddles1 #bbd ---- sleepers1 #bad ---- tram-plates1 #ahd ---- tube tunnels1 #agi ---- water-tanks1 #bii ,catch-siding1 #bf ,centre line of railway1 #cb ,chairs1 #bjf ,channelling ballast1 #bca ,check-rails on sharp curves1 #bi1 #ea ,cinder ballast1 #bbg ,circular running-shed1 #bhi ,clay puddle1 #abg ,clocks at stations1 #bf ,coal-drops1 #bhb ,coffer-dams1 #abg ,comparison of bull-head and flange rails1 #aii ,compound rails1 #aij ,concrete foundations1 #aad ,continuous brakes1 #cj ,cost of permanent way1 #bda1 #bdb #cfb ,covered-way tunnels1 #agh ,crab bolts1 #bbc ,cranes1 #bhj1 #bid ,creosoted sleepers1 #baa ,cross-over road1 #bcc ,crossings made of rails1 #bcg ,cross-sections1 #cc ,culverts and drains1 #gd ,curve alterations1 #ab ,curves1 #di ,cutting rails on curves1 #bbi ,cylinder foundations1 #aaf ,d ,datum line1 #h ,deck or floor of girder bridges1 #acc ,deposited plans1 #d1 #f ,depths of cuttings1 #aj ,derrick crane1 #bii ,detached lock1 #ccb ,detonator or fog signals1 #ccd ,detours on mountain-sides1 #c ,deviation1 limits of1 #f ---- of centre line1 #ab ---- of levels1 #ab ,diagram sketches of bridges1 #adi ,diamond crossing1 #bcg ,disc or ground signals1 #cbb ---- wheels1 #dh ,distant signal1 #ah1 #cad1 #cbb ,diversion of roads1 etc41 #f ,dobbin-cart1 #fg ,dock platforms1 #bea ,double-line junction1 #bca ---- slip points1 #bcc ,dry stone backing1 #afb ,e ,earthworks1 #fj ,edge rails1 #ahe ,electric motive-power1 #cee ---- repeater1 #bb1 #ccd ---- train-staff instrument1 #cdd ,embankment on bog1 #ga ,engine bogie1 #ec1 #ef1 #cjd ---- triangle1 #bij ,engine turntables1 #bg1 #bhi ,enlargements on parliamentary plans1 #af ,entrances to tunnels1 #agf ,estimate1 #ad ,expansion of rails1 #bbh ,extract from ,government ,standing ,orders and ,regulations1 #f ,f ,facing-bolt lock1 #cae ---- points1 #bj ---- ---- distance1 #bj ---- point locks1 #bb ,fang clips1 #bbd ,fastenings1 #bah ,fences enclosing line1 #ad1 #gc ---- on bridges1 #aj ---- on road approaches1 #aj ,fish bolts1 #bjc1 #bbj ---- plates1 #ahh1 #bjc ---- plate liners1 #bjf ,flag signals1 #cac ,flag-top culverts1 #gf ,flange rail1 #aia ,floor or deck of girder bridges1 #acc ,floors for goods-sheds1 #bhj ,flying junction1 #bca ,fog or detonator signals1 #ccd ,footbridges1 #bf1 #adg1 #adi ,footings of foundations1 #aaa ,foundations1 #aaa ,four-line system1 #cea ,g ,gantry crane1 #bid ,gate-alarm1 #ccf ,gates for level crossings1 #gd ,gauge of railways1 #cg1 #ch ,girder bridges1 #aaj ,glazed roofs over platforms1 #bgb ,goliath crane1 #big ,goods-sheds1 #bgc ,government grants to railways1 #cdi ---- ,standing ,orders1 #d1 #f ,gradient alterations1 #ab ,gradients1 #db ---- influencing loads1 #dc ---- in tunnels1 #aff ,gravel ballast1 #bbe ---- foundations1 #aac ,guard-rails1 #ea ,guide-piles1 #abg ,h #cfc ,half-round sleepers1 #baa ,hand-brakes on trucks1 #df ,headings in tunnels1 #afi ,headway and span of public-road bridges1 #aj ,height of platforms1 #bd ,heights of embankments1 #aj ,high-level viaduct1 #ha1 #hc ,high-speed running1 #ced ,home signals1 #ah1 #cad ,houses of labouring classes1 #aj ,i ,inclination of ramps1 #bf ,inside keys for chairs1 #bjg ,inspection of new line1 #ah ---- of tunnel work1 #agf ,interlocking of signals1 #bb1 #cad1 #ccj ,iron-tube tunnels1 #agi ,island-platform station1 #beh ,j ,jack-arches of brickwork1 #ade ---- of concrete1 #aci ,jib crane1 #bif ,jim ,crow1 #bci ,junction signals1 #bj1 #cbc ---- with existing line1 #f ,k ,keys for chairs1 #bjg ,kinsua ,viaduct1 #ig ,l ,lavatories and conveniences1 #bfj ,laying permanent way1 #bbe ,level crossings1 #aj ,life of steel rails1 #aic ,lift-bridge1 #hg ,light railways standard gauge1 #da ,limits of deviation1 #f1 #af ,loa ,viaduct1 #ajb ,loads of locomotive engines1 #dd ,location of railway1 #a ,lock and block signals1 #cdb1 #cec ,longitudinal sleepers1 #baj ,low viaduct arching1 #abi ,low-level viaduct1 #ha1 #hc ,m ,made ground1 #aaa ,marking steel rails1 #aie ,mechanical drills1 #agb ---- gates1 #cce ,mile-posts1 #cj ,n ,names of stations1 #bd ,narrow-gauge railways1 #dj ,natural features of country1 #a ---- ground1 #aaa ,navigable rivers1 #ha ,o ,occupation bridges1 #aaj ,ordinary crossing1 #bce ,ordnance maps1 #c ,outside guard-rails1 #ec ---- keys for chairs1 #bjg ,over-line arch bridges1 #ajc ,p ,parapets on viaducts1 #bh ,parliamentary estimate1 #ad ---- plan and section1 #f1 #h ,pedestal water-tanks1 #cjb ,piers of cast iron1 #ig ---- of masonry1 #ie ---- of timber1 #ajb ---- of wrought-iron and steel1 #ig ,pile foundations1 #aad ,plate-iron troughing1 #adc ,platform roofs1 #bfd ,platforms 7requirements of71 #bd ,plenum system of sinking1 #aai ,pneumatic process of sinking1 #abi ,points1 or switches1 #bce ,portage viaduct1 #ajb ,power to purchase land1 #f ,preservation of timber1 #baa ,private-road bridges1 #aaj ,provincial grants to railways1 #cdi ,public-road bridges1 #aj1 #ajc ---- level crossing1 #h ,r #cfd ,radial axle-boxes1 #eh ,rails1 #ahb ,railway bills1 #af ---- ,clauses ,act1 #f ---- fences1 #ad ---- slope1 #fa1 #ff1 #gb ,railways of different ranks1 #cdh ,ramps to platforms1 #bd ,recommendations as to working of railways1 #cj ,rectangular running-sheds1 #bhi ,reduced speed on curves1 #ej ,refuge sidings1 #ca1 #cea ,relative costs of narrow-gauge and light railways1 #da ,renewal of under-line bridges1 #aea ,repeater signal1 #bb1 #ccd ,requirements of ,board of ,trade1 #ah ,retaining walls1 #aei ,reverse curves1 #ea ,roadside station1 #bec ,rock foundations1 #aac ,rocking-bar1 #caf ,roof-principals1 #bfd ,roofs over roadside platforms1 #bgb ,rope-haulage1 #di ,route of railway1 #a ,royal assent1 #af ,runaway points1 #bcc ,s ,safety-points1 #bd1 #cai ,sandy foundations1 #aac ,scales for ,parliamentary plans1 #f1 #af ,scissors cross-over1 #bcc ,screw piles1 #aad ,semaphore signals1 #cac ,semi-circular running-sheds1 #bhi ,separate lines for through traffic1 #ceh ,service roads1 #fi ,shafts in tunnels1 #afg ,sheeting-piles1 #abg ,side-cutting1 #fa ,side recesses in tunnels1 #agf ,sidings1 #bd ,signal-cabins1 #cbh ,signal-detector1 #cae1 #cah ,signals1 #cac ---- at junctions1 #bj1 #cbc ,signals 7requirements of71 #bj ,six-wheeled carriage1 #ed ,sleepers1 #bji ,slip-points1 #bcc ,slope of cutting1 #fa ---- of embankment1 #ff ,slotted signals1 #cbf ,snake-heads1 #ahd ,soft deep bog1 #gj ,soiling earthwork1 #ff ,sorting-sidings1 #bhe ,span and headway of ,p4 ,r4 bridges1 #aj ,spans of large railway bridges1 #aeh ,spikes1 #bbb ,spirals1 #ce ,spoil-bank1 #fj ,sprags1 #df ,square crossing1 #bcc ,standing orders1 #d1 #f ,starting-signal1 #ah1 #cad ,station buildings1 #bfj ---- roofs1 #bfd ,stations1 #bdh ---- near viaducts1 #bd ---- on gradients1 #bf ,steel and wrought-iron sleepers1 #bag ---- rails1 #aij ,steps for side-lying ground1 #gj ---- of staircases1 #bf ,stone sleepers1 #baj ,strain on steel1 #bg ---- on wrought-iron1 #bg ,suburban traffic1 #ceb ,subways1 #bf ,super-elevation of rail1 #bcj ,supervision of tunnel-work1 #agf ,swing-bridges1 #hc1 #hg ,switches or points1 #bce ,syphon culverts1 #gi ,t ,tamping-bar1 #bci ,terminal station1 #bec ,tests for steel rails1 #aid ,three-throw switches1 #bcc ,thrust-girders for retaining walls1 #afa ,tie-bars1 #bbd ,timber bridges1 #ie ,timbering of tunnels1 #agj ,timber-pile foundations1 #aad ,time for construction1 #ah ,tip head1 #fg #cfe ,tip-waggon1 #fi ,tools for permanent way1 #bci ---- for tunnel-work1 #agb ,trailing-points1 #bj ,train-staff on single line1 #cdb ,train-tickets1 #cdc ,tramplates of cast-iron1 #ahd ,tramway rails1 #aii ,trap-points1 #cai ,travelling-crane1 #bif ,traversing bridge1 #he ,trimming slopes1 #gb ,trough girders1 #ace ,tunnel faces1 or entrance1 #agf ---- headings1 #afi ---- sections1 #agf ---- shafts1 #afg ,tunnels1 #f1 #aj1 #afb ---- composed of cast-iron segments1 #agi ---- drainage of1 #aff ---- through cities1 #agh ---- under rivers1 #aha ,turn-out1 #bcc ,turntables1 #bhg ,u ,under-line arch bridges1 #ajc1 #abi ,v ,vacuum system of sinking1 #aai ,verandah on platform1 #bfa ,viaduct parapets1 #bh ,viaducts of timber1 #ie ---- over rivers1 #hc ,viaducts over valleys1 #ia ---- to be shown on section1 #aj ,w ,waggon turn-table1 #bib ,waiting-rooms1 #bea ,warehouse crane1 #bid ,water-column1 #cjb ,water-jet piles1 #aaf ,water-tables1 #bbg ,water-tanks1 #bii ,wear of fish-plates1 #bje ,wear of steel rails1 #aic ,weeping-holes1 #afa1 #agd ,weights of locomotive engines1 #cjd ,well foundations1 #abc ,wheel-base of engine bogie1 #ei ,wheel-guards on viaducts1 #bh ,widths of public-road bridges1 #aj ,winding engines1 #ahe ,wind-pressure1 #bh ,wooden-centre wheels1 #dh ,wooden culverts1 #gf ---- screws1 #bbc ---- tramway1 #ahb ---- water-tanks1 #cja ,working plans and sections1 #cb ,wrought-iron column piers1 #ig ---- and steel sleepers1 #bag ---- piles1 #aaf ---- rails1 #ahf ---- water-tanks1 #cja ,z ,zigzags1 #ce ,,printed ,,by ,,william ,,clowes ,,and ,,sons1 ,,limited1 ,,london ,,and ,,beccles4 ,,engineering1 ,,strength ,,of ,,materials1 ,,etc4 ,,the ,,strength ,,of ,,materials ,,and ,,structures3 the ,strength of ,materials as depending on their ,quality and as ascertained by ,testing ,apparatus4 ,by ,sir ,j4 ,,anderson1 ,c4,e41 ,,ll4,d41 ,f4,r4,s4,e4 ,with #ff ,illustrations4 ,crown #hvo1 #cs4 #f;d4 ,,railway ,,appliances3 a ,description of ,details of ,railway ,construction subsequent to the completion of the ,earthworks and ,structures4 ,by ,sir ,,john ,,wolfe ,,barry1 ,k4,c4,b41 ,f4,r4,s4 ,with #bah ,illustrations4 ,crown #hvo1 #ds4 #f;d4 ,,mechanics ,,applied ,,to ,,engineering4 ,by ,,john ,,goodman1 ,wh4,sch41 ,m4,i4,c4,e41 ,m4,i4,m4,e41 ,professor of ,engineering in the ,university of ,leeds4 ,with #gad ,illustrations and numerous ,examples4 ,crown #hvo1 #is4 net4 ,,railway ,,appliances ,,and ,,operations4 ,for the ,use of ,railway ,employs4 ,by ,,edward ,s4 ,,hadley1 the ,great ,western ,railway's ,divisional ,superintendent's ,office1 ,newport1 ,monmouth4 ,in the press4 ,,engineer',s ,,valuing ,,assistant3 being a ,practical ,treatise on the ,valuation of ,colleries and ,other ,mines1 etc4 ,by ,h4 ,d4 ,,hoskold4 ,with an ,introductory ,note by ,,peter ,,gray4 #hvo1 #gs4 #f;d4 net4 ,,practical ,,hydraulic 7,,water ,,supply ,,and ,,drainage7 ,,tables ,,and ,,diagrams4 ,by ,c4 ,e4 ,,housden4 ,with #f ,plates and #g ,diagrams in the ,text4 ,crown #hvo1 #cs4 #f;d4 ,,practical ,,earthwork ,,tables4 ,by ,c4 ,e4 ,,housden4 ,with #i ,plates4 ,crown #hvo1 #bs4 #f;d4 ,a ,,pocket-,,book ,,for ,,mechanical ,,engineers4 ,by ,,david ,,allan ,,low 7,whitworth ,scholar71 ,m4,i4,mech4,e41 ,professor of ,engineering1 ,east ,london ,technical ,college4 ,with over #a1jjj specially prepared ,illustrations4 ,fcp4 #hvo1 gilt edges1 rounded corners4 #gs4 #f;d4 ,,mechanics ,,for ,,engineers3 a ,text-book of ,intermediate ,standard4 ,with #bjj ,diagrams and numerous ,examples4 ,by ,,arthur ,,morley1 ,m4,sc41 ,professor of ,mechanical ,engineering in ,university ,college1 ,nottingham4 ,crown #hvo1 #ds4 net4 ,,strength ,,of ,,materials4 ,by ,,arthur ,,morley1 ,m4,sc41 ,professor of ,mechanical ,engineering in ,university ,college1 ,nottingham4 ,with #bdh ,diagrams and numerous ,examples4 #hvo1 #gs4 #f;d4 net4 ,,light ,,railway ,,construction4 ,by ,,richard ,,marion ,,parkinson1 ,assoc4 ,m4,inst4,c4,e4 ,with #he ,diagrams4 #hvo1 #ajs4 #f;d4 net4 ,,graphics2 or1 the ,art of ,calculation by ,drawing ,lines1 applied especially to ,mechanical ,engineering4 ,by ,,robert ,h4 ,,smith1 formerly ,professor of ,engineering1 ,mason ,college1 ,birmingham4 ,part ,i4 ,with separate ,atlas of #bi ,plates containing #ig ,diagrams4 #hvo1 #aes4 6--#che4png-- ,,the ,,theory ,,of ,,stresses ,,in ,,girders ,,and ,,similar ,,structures2 with ,practical ,observations on the ,strength and other ,properties of ,materials4 ,by ,,bindon ,b4 ,,stoney1 ,,ll4,d41 ,f4,r4,s41 ,m4,i4,c4,e4 ,with #e ,plates and #adc ,illustrations in the ,text4 ,royal #hvo1 #cfs4 ,,the ,,testing ,,of ,,materials ,,of ,,construction4 ,a ,textbook for the ,engineering ,laboratory and a ,collection of the ,results of ,experiment4 ,by ,w4 ,,cawthorne ,,unwin1 ,f4,r4,s41 ,b4,sc4 ,with #e ,plates and #ahh ,illustrations and ,diagrams4 #hvo1 #afs4 net4 ,,engineering ,,construction ,,in ,,iron1 ,,steel1 ,,and ,,timber4 ,by ,,william ,,henry ,,warren4 ,with #ac ,folding ,plates and #cge ,diagrams4 ,medium #hvo1 #afs4 net4 ,,the ,,sea ,,coast3 ,destruction1 ,littoral ,drift1 ,protection4 ,by ,w4 ,h4 ,,wheeler1 ,m4,inst4 ,c4,e4 ,with #ch ,illustrations and ,diagram4 ,medium #hvo1 #ajs4 #f;d4 net4 ,a ,,practical ,,manual ,,of ,,tides ,,and ,,waves4 ,by ,w4 ,h4 ,,wheeler1 ,m4,inst4 ,c4,e4 ,with #ai ,illustrations4 #hvo1 #gs4 #f;d4 net4 ,,machine ,,drawing ,,and ,,design4 ,,an ,,introduction ,,to ,,machine ,,drawing ,,and ,,design4 ,by ,,david ,,allan ,,low1 ,m4,i4,mech4,e4 ,with #aec ,illustrations and ,diagrams4 ,crown #hvo1 #bs4 #f;d4 ,a ,,pocket-,,book ,,for ,,mechanical ,,engineers4 ,by ,,david ,,allan ,,low1 ,m4,i4,mech4,e4 ,fcp4 #hvo1 #gs4 #f;d4 ,,the ,,diagram ,,measurer4 ,an ,instrument for ,measuring the ,areas of ,irregular ,figures1 and specially useful for determining the ,mean ,effective ,pressure from ,indicator ,diagrams from ,steam1 ,gas and other ,engines4 ,by ,,david ,,allan ,,low1 ,m4,i4,mech4,e4 ,with full instructions1 #as4 ,a ,,manual ,,of ,,machine ,,drawing ,,and ,,design4 ,by ,,david ,,allan ,,low and ,,alfred ,,william ,,bevis4 ,with over #gjj ,illustrations4 #hvo1 #gs4 #f;d4 ,,machine ,,design1 ,,construction ,,and ,,drawing3 a ,textbook for the ,use of ,young ,engineers4 ,by ,,henry ,j4 ,,spooner1 ,c4,e41 ,m4,i4,mech4,e41 ,f4,g4,s41 etc41 ,director and ,professor in the ,polytechnic ,school of ,engineering4 ,with #hf ,tables and numerous ,exercises4 ,illustrated by over #a1djj ,drawings and ,figures4 #hvo1 #ajs4 #f;d4 net4 ,,machine ,,drawing ,,and ,,design ,,for ,,beginners3 an ,introductory ,work for the ,use of ,technical ,students4 ,by ,,henry ,j4 ,,spooner1 ,c4,e41 ,m4,i4,mech4,e41 ,f4,g4,s41 etc41 ,director and ,professor in the ,polytechnic ,school of ,engineering4 ,crown #dto1 price #cs4 #f;d4 ,,the ,,elements ,,of ,,machine ,,design4 ,,part ,i4 ,general ,principles2 ,strength of ,materials2 ,rivets1 ,bolts1 and other ,fastenings2 ,journals and ,shafting2 ,couplings2 ,pedestals2 ,transmission of ,power by ,gearing1 ,belting1 ,ropes1 and ,chains4 ,by ,w4 ,,cawthorne ,,unwin1 ,,ll4,d41 ,f4,r4,s41 ,b4,sc41 ,m4,i4,c4,e41 ,hon4 ,mem4 ,inst4 ,mech4 ,e41 ,hon4 ,mem4 ,am4 ,soc4 ,mech4 ,e41 ,foreign ,hon4 ,mem4 ,am4 ,academy of ,arts and ,sciences4 ,with #chg ,figures4 #hvo1 #gs4 #f;d4 net4 ,,part ,,ii4 ,chiefly on ,engine ,details4 ,with #bei ,diagrams1 etc4 ,crown #hvo1 #fs4 ,,longmans1 ,,green1 ,,co4 ,,london1 ,,new ,,york1 ,,bombay1 ,,and ,,calcutta4 ,transcriber's ,note3 ,unprinted punctuation was added1 where appropriate4 ,the illustrations identified as numbered figures are all full-page without captions4 ,when illustrations interrupt the text of a paragraph1 they were moved to precede that paragraph4 ,for ease of use of the index1 page numbers are displayed in the right margin for only pages that contain text4 ,words and phrases in italics are surrounded by underscores1 like this4 ,superscripted letters and numbers are preceded by a carat1 e4g4 ,co4 ,use of hyphens was made consistent4 ,obsolete and alternative spellings were left unchanged4 ,spelling corrections are noted below3 #8transhipment' to #8transshipment' 444 delay in transshipment444 pg #da #8steepier' to #8steeper' 444 introduce steeper gradients 444 pg #de #8guage' to #8gauge' 444 #h inch gauge1444 pg #dh #8guage' to #8gauge' 444 on #c-;foot narrow-gauge railways 444 pg #aic #8breaks' to #8brakes' 444 the working of the brakes4444 pg #aic #8petition' to #8partition' 444 plate partition across 444 pg #cja #8close' to #8closed' 444 is kept closed by the pressure 444 pg #cjb