,illustration ,,scientific ,,american ,,supplement ,,no4 #fdg ,,new ,,york1 ,,may #bf1 #ahhh ,scientific ,american ,supplement4 ,vol4 ,,xxv41 ,no4 #fdg4 ,scientific ,american established #ahde ,scientific ,american ,supplement1 #e a year4 ,scientific ,american and ,supplement1 #g a year4 99 99 99 99 99 ,,table ,,of ,,contents4 ,,page4 ,i4 ,,architecture4--,elements of ,architectural ,design4--,by ,h4 ,h4 ,statham4--,continuation of this important contribution to building art1 ,gothic1 ,roman1 ,romanesque1 and ,medival architecture compared4--#bf illustrations4 #ajcci ,the ,evolution of the ,modern ,mill4--,by ,c4 ,j4 ,h4 ,woodbury4--,sibley ,college lecture treating of the buildings for mills4 #ajcbi ,,ii4 ,,chemistry4--,an ,automatic ,still4--,by ,t4 ,maben4--,an improved apparatus for making distilled water4--#a illustration4 #ajcce ,testing ,indigo ,dyes4--,simple and practical chemical tests of indigo products4 #ajcdb ,,iii4 ,,civil ,,engineering4--,railway ,bridge at ,lachine4--,great steel bridge across the ,st4 ,lawrence near ,montreal4--#b illustrations4 #ajccc ,,iv4 ,,electricity4--,influence ,machines4--,by ,mr4 ,james ,wimshurst4--,a ,london ,royal ,institution lecture1 of great value as giving a full account of the recent forms of generators of static electricity4--#ad illustrations4 #ajcbg ,v4 ,,hygiene4--,the ,care of the ,eyes4--,by ,prof4 ,david ,webster1 ,m4,d4--,a short and thoroughly practical paper on the all important subject of preservation of sight4 #ajcda ,,vi4 ,,mechanical ,,engineering4--,economy ,trials of a ,non-condensing ,steam ,engine4--,by ,mr4 ,p4 ,w4 ,winans1 ,m4,i4,c4,e4--,interesting notes on testing steam engines4 #ajcca ,the ,mechanical ,equivalent of ,heat4--,by ,prof4 ,de ,volson ,wood4--,a review of ,mr4 ,hanssen's recent paper1 with interesting discussion of the problem4 #ajcca ,,vii4 ,,meteorology4--,the ,meteorological ,station on ,mt4 ,santis4--,a new observatory recently erected in ,switzerland1 at an elevation of #h1bjb feet above the sea4--#a illustration4 #ajcda ,,viii4 ,,naval ,,engineering4--,improved ,screw ,propeller4--,mr4 ,b4 ,dickinson's new propeller4--,its form and peculiarities and results4--#d illustrations4 #ajccc ,,ix4 ,,photography4--,manufacture of ,photographic ,sensitive ,plates4--,description of a factory recently erected for manufacturing dry plates4--,the arrangement of rooms1 machinery1 and process4--#aj illustrations4 #ajccf ,x4 ,,technology4--,cotton ,seed ,oil4--,how cotton seed oil is made1 and the cost and profits of the operation4 #ajcce ,improved ,dobby4--,an improved weaving apparatus described and illustrated4--#a ,illustration4 #ajccc ,sulphur ,mines in ,sicily4--,by ,philip ,carroll1 ,u4 ,s4 ,consul1 ,florence4--,how sulphur is made in ,sicily1 percentage1 composition of the ore1 and full details4 #ajccd ,the ,use of ,ammonia as a ,refrigerating ,agent4--,by ,mr4 ,t4 ,b4 ,lightfoot1 ,m4,i4,c4,e4--,an elaborate discussion of the theory and practice of ammonia refrigerating1 including the hydrous and anhydrous systems1 with conditions of economy4 #ajccg 99 99 99 99 99 ,,influence ,,machines4#a ,footnote #a3 ,lecture delivered at the ,royal ,institution1 ,april #bg1 #ahhh4 ,for the above and for our illustrations we are indebted to ,engineering4 ,,by ,,mr4 ,,james ,,wimshurst4 ,i have the honor this evening of addressing a few remarks to you upon the subject of influence machines1 and the manner in which ,i propose to treat the subject is to state as shortly as possible1 first1 the historical portion1 and afterward to point out the prominent characteristics of the later and the more commonly known machines4 ,the diagrams upon the screen will assist the eye to the general form of the typical machines1 but ,i fear that want of time will prevent me from explaining each of them4 ,in #agfb ,wilcke described a simple apparatus which produced electrical charges by influence1 or induction1 and following this the great ,italian scientist ,alexander ,volta in #agge gave the electrophorus the form which it retains to the present day4 ,this apparatus may be viewed as containing the germ of the principle of all influence machines yet constructed4 ,another step in the development was the invention of the doubler by ,bennet in #aghf4 ,he constructed metal plates which were thickly varnished1 and were supported by insulating handles1 and which were manipulated so as to increase a small initial charge4 ,it may be better for me to here explain the process of building up an increased charge by electrical influence1 for the same principle holds in all of the many forms of influence machines4 ,this ,volta electrophorus1 and these three blackboards1 will serve for the purpose4 ,i first excite the electrophorus in the usual manner1 and you see that it then influences a charge in its top plate2 the charge in the resinous compound is known as negative1 while the charge induced in its top plate is known as positive4 ,i now show you by this electroscope that these charges are unlike in character4 ,both charges are1 however1 small1 and ,bennet used the following system to increase them4 ,let these three boards represent ,bennet's three plates4 ,to plate ,no4 #a he imparted a positive charge1 and with it he induced a negative charge in plate ,no4 #b4 ,then with plate ,no4 #b he induced a positive charge in plate ,no4 #c4 ,he then placed the plates ,nos4 #a and #c together1 by which combination he had two positive charges within practically the same space1 and with these two charges he induced a double charge in plate ,no4 #b4 ,this process was continued until the desired degree of increase was obtained4 ,i will not go through the process of actually building up a charge by such means1 for it would take more time than ,i can spare4 ,in #aghg ,carvallo discovered the very important fact that metal plates when insulated always acquire slight charges of electricity2 following up those two important discoveries of ,bennet and ,carvallo1 ,nicholson in #aghh constructed an apparatus having two disks of metal insulated and fixed in the same plane4 ,then by means of a spindle and handle1 a third disk1 also insulated1 was made to revolve near to the two fixed disks1 metallic touches being fixed in suitable positions4 ,with this apparatus be found that small residual charges might readily be increased4 ,it is in this simple apparatus that we have the parent of influence machines 7see ,fig4 #a71 and as it is now a hundred years since ,nicholson described this machine in the ,phil4 ,trans41 ,i think it well worth showing a large sized ,nicholson machine at work to-night 7see ,fig4 #aa1 above74 ,illustration3 ,figs4 #a-i4 ,in #ahbc ,ronalds described a machine in which the moving disk was attached to and worked by the pendulum of a clock4 ,it was a modification of ,nicholson's doubler1 and he used it to supply electricity for telegraph working4 ,for some years after these machines were invented no important advance appears to have been made1 and ,i think this may be attributed to the great discoveries in galvanic electricity which were made about the commencement of this century by ,galvani and ,volta1 followed in #ahca to #aheg by the magnificent discoveries of ,faraday in electro-magnetism1 electro-chemistry1 and electro-optics1 and no real improvement was made in influence machines till #ahfj1 in which year ,varley patented a form of machine shown in ,fig4 #b4 ,it also was designed for telegraph working4 ,in #ahfe the subject was taken up with vigor in ,germany by ,toepler1 ,holtz1 and other eminent men4 ,the most prominent of the machines made by them are figured in the diagrams 7,figs4 #c to #f71 but time will not admit of my giving an explanation of the many points of interest in them2 it being my wish to show you at work such of the machines as ,i may be able1 and to make some observations upon them4 ,in #ahff ,bertsch invented a machine1 but not of the multiplying type2 and in #ahfg ,sir ,william ,thomson invented the form of machine shown in ,fig4 #g1 which1 for the purpose of maintaining a constant potential in a ,leyden jar1 is exceedingly useful4 ,the ,carre machine was invented in #ahfh1 and in #ahhj the ,voss machine was introduced1 since which time the latter has found a place in many laboratories4 ,it closely resembles the ,varley machine in appearance1 and the ,toepler machine in construction4 ,in condensing this part of my subject1 ,i have had to omit many prominent names and much interesting subject matter1 but ,i must state that in placing what ,i have before you1 many of my scientific friends have been ready to help and to contribute1 and1 as an instance of this1 ,i may mention that ,prof4 ,sylvanus ,p4 ,thompson at once placed all his literature and even his private notes of reference at my service4 ,i will now endeavor to point out the more prominent features of the influence machines which ,i have present1 and1 in doing so1 ,i must ask a moment's leave from the subject of my lecture to show you a small machine made by that eminent worker ,faraday1 which1 apart from its value as his handiwork1 so closely brings us face to face with the imperfect apparatus with which he and others of his day made their valuable researches4 ,the next machine which ,i take is a ,holtz4 ,it has one plate revolving1 the second plate being fixed4 ,the fixed plate1 as you see1 is so much cut away that it is very liable to breakage4 ,paper inductors are fixed upon the back of it1 while opposite the inductors1 and in front of the revolving plate1 are combs4 ,to work the machine 7#a7 a specially dry atmosphere is required2 7#b7 an initial charge is necessary2 7#c7 when at work the amount of electricity passing through the terminals is great2 7#d7 the direction of the current is apt to reverse2 7#e7 when the terminals are opened beyond the sparking distance1 the excitement rapidly dies away2 7#f7 it does not part with free electricity from either of the terminals singly4 ,it has no metal on the revolving plates1 nor any metal contacts2 the electricity is collected by combs which take the place of brushes1 and it is the break in the connection of this circuit which supplies a current for external use4 ,on this point ,i cannot do better than quote an extract from page #cci of ,sir ,william ,thomson's ,papers on ,electrostatics and ,magnetism1 which runs3 ,holtz's now celebrated electric machine1 which is closely analogous in principle to ,varley's of #ahfj1 is1 ,i believe1 a descendant of ,nicholson's4 ,its great power depends upon the abolition by ,holtz of metallic carriers and metallic make-and-break-contacts4 ,it differs from ,varley's and mine by leaving the inductors to themselves1 and using the current in the connecting arc4 ,in respect to the second form of ,holtz machine 7,fig4 #d7 ,i have very little information1 for since it was brought to my notice nearly six years ago ,i have not been able to find either one of the machines or any person who had seen one4 ,as will be seen by the diagram1 it has two disks revolving in opposite directions1 it has no metal sectors and no metal contacts4 ,the connecting arc circuit is used for the terminal circuit4 ,altogether ,i can very well understand and fully appreciate the statement made by ,professor ,holtz in ,uppenborn's ,journal of ,may1 #ahha1 wherein he writes that for the purpose of demonstration ,i would rather be without such machines4 ,the first type of ,holtz machine has now in many instances been made up in multiple form1 within suitably constructed glass cases1 but when so made up1 great difficulty has been found in keeping each of the many plates to a like excitement4 ,when differently excited1 the one set of plates furnished positive electricity to the comb1 while the next set of plates gave negative electricity2 as a consequence1 no electricity passed the terminal4 ,to overcome this objection1 to dispense with the dangerously cut plates1 and also to better neutralize the revolving plate1 throughout its whole diameter1 ,i made a large machine having twelve disks #b ft4 #g in4 in diameter1 and in it ,i inserted plain rectangular slips of glass between the disks1 which might readily be removed2 these slips carried the paper inductors4 ,to keep all the paper inductors on one side of the machine to a like excitement1 ,i connected them together by a metal wire4 ,the machine so made worked splendidly1 and your late president1 ,mr4 ,spottiswoode1 sent on two occasions to take note of my successful modifications4 ,the machine is now ten years old1 but still works perfectly4 ,i will show you a smaller sized one at work4 ,the next machine for observations is the ,carre 7,fig4 #h74 ,it consists essentially or a disk of glass which is free to revolve without touch or friction4 ,at one end of a diameter it moves near to the excited plate of a frictional machine1 while at the opposite end of the diameter is a strip of insulting material1 opposite which1 and also opposite the excited amalgam plate1 are combs for conducting the induced charges1 and to which the terminals are metallically connected2 the machine works well in ordinary atmosphere1 and certainly is in many ways to be preferred to the simple frictional machine4 ,in my experiments with it ,i found that the quantity of electricity might be more than doubled by adding a segment of glass between the amalgam cushions and the revolving plate4 ,the current in this type of machine is constant4 ,the ,voss machine has one fixed plate and one revolving plate4 ,upon the fixed plate are two inductors1 while on the revolving plate are six circular carriers4 ,two brushes receive the first portions of the induced charges from the carriers1 which portions are conveyed to the inductors4 ,the combs collect the remaining portion of the induced charge for use as an outer circuit1 while the metal rod with its two brushes neutralizes the plate surface in a line of its diagonal diameter4 ,when at work it supplies a considerable amount of electricity4 ,it is self-exciting in ordinary dry atmosphere4 ,it freely parts with its electricity from either terminal1 but when so used the current frequently changes its direction1 hence there is no certainty that a full charge has been obtained1 nor whether the charge is of positive or negative electricity4 ,i next come to the type of machine with which ,i am more closely associated1 and ,i may preface my remarks by adding that the invention sprang solely from my experience gained by constantly using and experimenting with the many electrical machines which ,i possessed4 ,it was from these ,i formed a working hypothesis which led me to make my first small machine4 ,it excited itself when new with the first revolution4 ,it so fully satisfied me with its performance that ,i had four others made1 the first of which ,i presented to this ,institution4 ,its construction is of a simple character4 ,the two disks of glass revolve near to each other and in opposite directions4 ,each disk carries metallic sectors2 each disk has its two brushes supported by metal rods1 the rods to the two plates forming an angle of #ij deg4 with each other4 ,the external circuit is independent of the brushes1 and is formed by the combs and terminals4 ,illustration3 ,fig4 #aj4 ,the machine is self-exciting under all conditions of atmosphere1 owing probably to each plate being influenced by and influencing in turn its neighbor1 hence there is the minimum surface for leakage4 ,when excited1 the direction of the current never changes2 this circumstance is due1 probably1 to the circuit of the metallic sectors and the make and break contacts always being closed1 while the combs and the external circuit are supplemental1 and for external use only4 ,the quantity of electricity is very large and the potential high4 ,when suitably arranged1 the length of spark produced is equal to nearly the radius of the disk4 ,i have made them from #b in4 to #g ft4 in diameter1 with equally satisfactory results4 ,the diagram1 ,fig4 #i1 shows the distribution of the electricity upon the plate surfaces when the machine is fully excited4 ,the inner circle of signs corresponds with the electricity upon the front surface of the disk4 ,the two circles of signs between the two black rings refer to the electricity between the disks1 while the outer circle of signs corresponds with the electricity upon the outer surface of the back disk4 ,the diagram is the result of experiments which ,i cannot very well repeat here this evening1 but in support of the distribution shown on the diagram1 ,i will show you two disks at work made of a flexible material1 which when driven in one direction close together at the top and the bottom1 while in the horizontal diameter they are repelled4 ,when driven in the reverse direction1 the opposite action takes place4 ,i have also experimented with the cylindrical form of the machine 7see ,fig4 #aj74 ,the first of these ,i made in #ahhb1 and it is before you4 ,the cylinder gives inferior results to the simple disks1 and is more complicated to adjust4 ,you notice ,i neither use nor recommend vulcanite1 and it is perhaps well to caution my hearers against the use of that material for the purpose1 for it warps with age1 and when left in the daylight it changes and becomes useless4 ,illustration3 ,figs4 #aa #ab4 ,i have now only to speak of the larger machines4 ,they are in all respects made up with the same plates1 sectors1 and brushes as were used by me in the first experimental machines1 but for convenience sake they are fitted in numbers within a glass case4 ,one machine has eight plates of #b ft4 #d in4 diameter2 it has been in the possession of the ,institution for about three years4 ,a second1 which has been made for this lecture1 has twelve disks1 each #b ft4 #f in4 in diameter4 ,the length of spark from it is #ac-e_/h in4 7see ,fig4 #ab74 ,during the construction of the machine every care was taken to avoid electrical excitement in any of its parts1 and after its completion several friends were present to witness the fitting of the brushes and the first start4 ,when all was ready the terminals were connected to an electroscope1 and the handle was moved so slowly that it occupied thirty seconds in moving one-half revolution1 and at that point violent excitement appeared4 ,the machine has now been standing with its handle secured for about eight hours4 ,no excitement is apparent1 but still it may not be absolutely inert4 ,of this each one present must judge1 but ,i will connect it with this electroscope 7,figs4 #ac and #ad71 and then move the handle slowly1 so that you may see when the excitement commences and judge of its absolutely reliable behavior as an instrument for public demonstration4 ,i may say that ,i have never1 under any condition1 found this type of machine to fail in its performance4 ,illustration3 ,fig4 #ac4 ,illustration3 ,fig4 #ad4 ,i now propose to show you the beautiful appearances of the discharge1 and then1 in order that you may judge of the relative capabilities of each of these three machines1 we will work them all at the same time4 ,the large frictional machine which is in use for this comparison is so well known by you that a better standard could not be desired4 ,in conclusion1 ,i may be permitted to say that it is fortunate ,i had not read the opinions of ,sir ,william ,thomson and ,professor ,holtz1 as quoted in the earlier part of my lecture1 previous to my own practical experiments4 ,for had ,i read such opinions from such authorities1 ,i should probably have accepted them without putting them to practical test4 ,as the matter stands1 ,i have done those things which they said ,i ought not to have done1 and ,i have left undone those which they said ,i ought to have done1 and by so doing ,i think you must freely admit that ,i have produced an electric generating machine of great power1 and have placed in the hands of the physicist1 for the purposes of public demonstration or original research1 an instrument more reliable than anything hitherto produced4 99 99 99 99 99 ,,violet ,,copying ,,ink4--,dissolve #dj parts of extract of logwood1 #e of oxalic acid and #cj parts of sulphate of aluminium1 without heat1 in #hjj parts of distilled water and #aj parts of glycerine2 let stand twenty-four hours1 then add a solution of #e parts of bichromate of potassium in #ajj parts of distilled water1 and again set aside for twenty-four hours4 ,now raise the mixture once to boiling in a bright copper boiler1 mix with it1 while hot1 #ej parts of wood vinegar1 and when cold put into bottles4 ,after a fortnight decant it from the sediment4 ,in thin layers this ink is reddish violet2 it writes dark violet and furnishes bluish violet copies4 99 99 99 99 99 ,,sibley ,,college ,,lectures4--#ahhg-hh4 ,,by ,,the ,,cornell ,,university ,,non-,,resident ,,lecturers ,,in ,,mechanical ,,engineering4 ,,the ,,evolution ,,of ,,the ,,modern ,,mill4#a ,footnote #a3 ,the lecture was illustrated by about fifty views on the screen1 which cannot be reproduced here1 showing photographs of mills and mechanical drawings of the methods of construction alluded to in the lecture4 ,,by ,c4 ,j4 ,h4 ,,woodbury1 ,,boston1 ,,mass4 ,the great factories of the textile industries in this country are fashioned after methods peculiarly adapted to the purposes for which they are designed1 particularly as regards the most convenient placing of machinery1 the distribution of power1 the relation of the several processes to each other in the natural sequence of manufacture1 and the arrangement of windows securing the most favorable lighting4 ,the floors and roofs embody the most economical distribution of material1 and the walls furnish examples of well known forms of masonry originating with this class of buildings4 ,these features of construction have not been produced by a stroke of genius on the part of any one man4 ,there has been no ,michael ,angelo1 no ,sir ,christopher ,wren1 whose epitaph bids the reader to look around for a monument2 but the whole has been a matter of slow1 steady growth1 advancing by hair's breadth2 and1 as the result of continual efforts to adapt means to ends1 an inorganic evolution has been effected1 resulting in the survival of the fittest1 and literally pushing the weaker to the wall4 ,this advance in methods has1 like all inventions1 resulted in the impairment of invested capital4 ,there are hundreds of mill buildings1 the wonder of their day1 now used for storage because they cannot be employed to sufficient advantage in manufacturing purposes to compete with the facilities furnished by mills of later design4 ,thus their owners have been compelled to erect new buildings1 and1 as far as the original purpose of manufacturing is concerned1 to abandon their old mills4 ,in the case of a certain cotton mill built about thirty years ago1 and used for the manufacture of colored goods of fancy weave1 the owners added to the plant by constructing a one story mill1 which proved to be peculiarly adapted to this kind of manufacture1 by reason of added stability1 better light1 and increased facilities for transferring the stock in process of manufacture2 and they soon learned not only that the old mill could not compete with the new one1 but that they could not afford to run it at any price2 the annual saving in the cost of gas1 as measured by the identical meter used to measure the supply to the old mill1 being six per cent4 on the cost of the new mill4 ,in another instance1 one of two cordage mills burned1 and a new mill of one story construction was erected in its place4 ,the advantage of manufacture therein was so great that the owners of the property changed the remaining old mill into a storehouse2 and now1 as they wish to increase their business1 it is to be torn down as a cumberer of the ground1 to make room for a building of similar construction to the new mill4 ,it is true that such instances pertain more particularly to industries and lines of manufacture where competition is close and conditions are exacting4 ,still they apply in a greater or less degree to nearly every industrial process in which a considerable portion of the expense of manufacture consists in the application of organized labor to machines of a high degree of perfection4 ,these changes have been solely due to the differences in the conditions imposed by improvement in the methods of manufacture4 ,the early mills of this country were driven by water power1 and situated where that could be developed in the easiest manner4 ,they were therefore placed in the narrow valleys of rapid watercourses4 ,the method of applying water power in that day being strictly limited to placing the overshot or breast wheel in the race leading from the canal to the river1 the mill was necessarily placed on a narrow strip of land between these two bodies of water1 with the race-way running under the mill4 ,to meet these conditions of location1 which was limited to this strip of land1 the mill must be narrow and short1 and the requisite floor area must be obtained by adding to the number of stories4 ,it was essential that the roof of such a mill should be strong and well braced in order to sustain the excessive stress brought to bear upon it4 ,the old factory roof was a curious structure1 with eaves springing out of the edge of hollow cornices1 the roof rising sharply until about six feet above the attic floor1 with an upright course of about three feet1 filled with sashes reaching to a second roof1 which1 at a more moderate pitch than the first slope1 trended to the ridge4 ,the attic was reduced to an approximately square room1 by placing sheathing between the columns underneath the sashes1 and ceiling underneath the collar beams above2 thus forming a cock-loft above and concealed spaces at the sides which diminished the practically available floor space in the attic4 ,this cock-loft and these concealed spaces became receptacles for rubbish and harbors for vermin1 both of which were frequent causes of fire4 ,the floors of such a mill were similar in their arrangement to those of a dwelling4 ,joists connecting the beams supported the floor2 and the under side was covered over by sheathing or lath and plaster1 thus forming1 as in the case of the roof1 hollow spaces which were a source of danger4 ,this method caused at the same time an extravagant distribution of material1 by the prodigal use of lumber and the unnecessary thickness of such floors1 and entailed an excessive amount of masonry in the walls4 ,mills built after this manner were frequently in odd dimensions2 and the machinery was necessarily placed in diversified arrangement1 calling forth a similar degree of wasted skill as that used in making a ,chinese puzzle conform to its given boundaries4 ,their area depended upon the topography of the site1 and their height upon the owner's pocket book4 ,there was in ,massachusetts a mill with ten floors1 built on land worth at that time ten cents or less per square foot1 which has been torn down and a new mill rebuilt in its place1 because1 since the advent of modern mills1 it has failed every owner by reason of the excessive expenditure necessary for the distribution of power1 for supervision1 and for the transfer of stock in process1 in comparison with the mills of their competitors1 built with greater ground area and less number of stories4 ,with the advent of the steam engine as prime mover in mills1 and the introduction of the turbine wheel with its trunk1 affording greater facilities in the application of water power1 the character of these buildings changed very materially1 though still retaining many of their old features4 ,one of the first of these changes may be noticed in the consideration which millwrights gave to the problem of fixing upon the dimensions of a mill so as to arrange the machinery in the most convenient manner4 ,although the floors were still hollow1 there was a better distribution of material1 the joists being deeper1 of longer span1 and resting upon the beams1 thus avoiding the pernicious method of wasting lumber1 and guarding against fracture by tenoning joists into the upper side of beams4 ,but this secondary type of mills was not honest in the matter of design4 ,the influence of architects who attempted effects not accordant with or subservient to the practical use of the property is apparent in such mills4 ,the most frequent of these wooden efforts at classic architecture was the common practice of representing a diminutive ,grecian temple surrounding a factory bell perched in mid air4 ,there were also windows with ,romanesque arches copied from churches1 and ,mansard roofs1 exiled from their true function of decorating the home1 covering a factory without an answering line anywhere on its flat walls4 ,i do not mean to criticise any of these elements of design in their proper place and environment2 but utility is the fundamental element in design1 and should be especially noticeable in a building constructed for industrial purposes1 and used solely as a source of commercial profit in such applications4 ,its lines therefore fulfill their true function in design in such measure as they suggest stability and convenience2 and this can be obtained in such structures without the adoption of bad proportions offensive to the taste4 ,in fact1 certain decorative effects have been made with good results2 but these have been wholly subordinate to the fundamental idea of utility4 ,the endurance with which brick will withstand frost and fires1 and the disintegrating forces of nature1 in addition to its resistance to crushing and the facility of construction1 constitute very important reasons for its value for building purposes4 ,but the use of this has been too often limited to plain brick in plain walls1 whose monotony portrayed no artistic effect beyond that furnished by a few geometrical designs of the most primitive form of ornament1 and falling far short of what the practice of recent years has shown to be possible with this material4 ,additions of cast iron serve as ornaments only in the phraseology of trade catalogues2 and the mixture of stone with brick shows results in flaring contrasts1 producing harsh dissonance in the effect4 ,the facades of such buildings show that this is brick1 this is stone1 or this is cast iron2 but they always fail to impress the beholder with the idea of harmonious design4 ,the use of finer varieties of clay in terra cotta figures laid among the brickwork furnishes a field of architectural design hardly appreciated4 ,the heavy mass of brick1 divided by regular lines of demarkation1 serves as the groundwork of such ornamentation1 while the suitable introduction in the proper places of the same material in terra cotta imparts the most appropriate elements of beauty in design2 for clay in both forms shows alike its capacity for utility and decoration4 ,the absorption of light by both forms of this material abates reflection1 and renders its proportions more clearly visible than any other substance used in building construction4 ,the modern mill has been evolved out of the various exacting conditions developed in the effort to reduce the cost of production to the lowest terms4 ,these conditions comprise in a great measure questions of stability1 repairs1 insurance1 distribution of power1 and arrangement of machinery4 ,in presenting to your attention some of the salient features of modern mill construction1 ,i do not assume to offer a general treatise upon the subject2 but propose to confine myself to a consideration of some topics which may not have been brought to your notice1 as they are still largely matters of personal experience which have not yet found their way into the books on the subject4 ,much of this1 especially the drawings thrown on the screen1 is obtained from the experience of the manufacturers' mutual insurance companies1 with which ,i am connected4 ,by way of explanation1 ,i will say that these companies confine their work to writing upon industrial property2 and there is not a mechanical process1 or method of building1 or use of raw material1 which does not have its relation to the question of hazard by fire1 by reason of the elements of relative danger which it embodies4 ,it is indeed fortunate that it has been found by experience that those methods of building which are most desirable for the underwriter are also equally advantageous for the manufacturer4 ,there is no pretense made at demands to compass the erection of fireproof buildings4 ,in fact1 as ,i have once remarked1 a fireproof mill is commercially impossible1 whatever effort may be made to overcome the constructive difficulties in the way of erecting and operating a mill which shall be all that the name implies4 ,the present practice is to build a mill of slow burning construction4 ,,foundations4 ,in considering the elements of such buildings1 ,i wish to devote a few words to the question of foundations1 because in the excessive loads imposed by this class of buildings1 and in the frequent necessity of constructing them upon sites where alluvial drift or quicksands form compressible foundations1 there is afforded an opportunity for the widest range of engineering skill in dealing with the problem4 ,in such instances1 a settling of the building must be foreseen and provided for1 in order that it may be uniform under the whole structure4 ,this is generally accomplished by means of independent foundations under the various points of pressure1 arranged so as to give a uniform intensity of pressure upon all parts of the foundation4 ,it is considered important to limit the load upon such foundations to two tons a square foot1 although loads frequently exceed this amount4 ,there is a large building in ,new ,york ,city which has recently been reconstructed1 and the foundations rearranged1 where the load reached to the enormous amount of six to ten tons per square foot4 ,it was a frequent occurrence in the class of high mills spoken of to impose loads of so much greater intensity upon the wall foundation than upon the piers under the columns of the mill1 that the floors became much lower at the walls than at the middle4 ,the stone for such foundations should be laid in cement rather than in mortar1 not merely because cement offers so much greater resistance to crushing1 but because its setting is due to chemical changes occurring simultaneously throughout the mass4 ,the hardening of mortar1 on the other hand1 is due to the drying out of the water mechanically contained with it1 and its final setting is caused by the action of the carbonic acid gas in the air4 ,although quicksands are never to be desired1 yet they will sustain heavy loads if suitably confined4 ,when inclined rock strata are met with1 all horizontal components of stress should be removed by cutting steps so that the foundation stones shall lie upon horizontal beds4 ,foundations are frequently impaired by the slow1 insidious action of springs or of water percolating from the canal which supplies the water power for the mill2 and the proper diversion of such streams should be carefully provided for4 ,in the question of foundations1 there is much of a general nature which is applicable to all structures2 but1 at the same time1 each case requires independent consideration of the circumstances involved4 ,,walls4 ,in addition to what has been said1 there is but little for me to offer on the subject of walls beyond the general question of stability4 ,in mill construction1 walls of uniform thickness have been displaced by pilastered walls1 about sixteen inches thick at the upper story1 and increasing four inches in thickness with each story below4 ,the remainder of the walls is from four to six inches less in thickness than at the pilasters4 ,frequently the outside dimensions of these pilasters are somewhat increased1 giving greater stability and artistic effect4 ,by leaving hollow flues within them1 and using these flues as conductors for heated air which may be forced in by a blower1 such pilasters afford a means for the most efficient method of warming the building4 ,consideration must be given to the contraction of brick masonry1 especially when an extension or addition is to be made to an older building4 ,this shrinkage amounts to about three-sixteenths of an inch to the rod1 an item which is of considerable importance in the floors of high buildings1 where the aggregate difference is very appreciable4 ,some degree of annoyance is caused by neglect to consider this element of shrinkage in reference to the window and door frames1 which should have a slight space above them allowing for such contraction4 ,this contraction is often the source of serious trouble in brick buildings with stone faces1 the shrinkage of the brick imposing excessive stress on the stone4 ,instances of this are quite frequent1 especially in large public buildings1 notably the capitol at ,hartford and the public building at ,philadelphia1 where the shivering of the joints of the stone work gave undue alarm1 on the general assumption that it indicated a dangerous structural weakness4 ,the difficulty has1 ,i believe1 been entirely remedied in both cases4 ,the limit of good practice on loads upon brickwork is eight to ten tons per square foot1 although it is true that these loads are largely exceeded at times4 ,it is not to be shown1 however1 that the limits of safety in regard to desirable construction should be confined to the use of masonry for any low buildings4 ,structures which may be said to be equal to those of brickwork1 as far as commercial risk is concerned1 can be built wholly or in part of wood so as to conform to all practical conditions of safety4 ,this statement does not apply except to low buildings of one or possibly two stories in height1 where the timber cannot be subjected to the intense blast of flame occurring when a high building is on fire4 ,mr4 ,george ,h4 ,corliss1 the eminent engine builder1 of ,providence1 first built a one-story machine shop1 with brick walls extending only to the base of the windows1 above this the windows being very close together1 with solid timber construction between them4 ,another method is to place upright posts reaching from the sill to the roof timbers1 and to lay three-inch plank on the outside of such posts up to the line of the windows4 ,a sheathing on the outside plank between the timbers is laid vertically and fastened to horizontal furring strips4 ,in some instances a small amount of mortar is placed over each of the furring strips4 ,the reason for this arrangement is to prevent the formation of vertical flues1 which are such a potent factor in the extension of fires4 ,,windows4 ,light is often limited or misapplied on account of faulty position or size of windows4 ,the use of pilastered walls permits the introduction of larger windows1 which are in most instances virtually double windows1 the two pairs of sashes being set in one frame separated by a mullion4 ,a more recent arrangement1 widely adopted in ,english practice1 is to place a swinging sash at the top of the window1 which can be opened1 when necessary1 to assist in the ventilation1 while the main sashes of the window are permanently fixed4 ,rough plate glass is used in such windows1 because it gives a softer and more diffused light1 which is preferred to that from ordinary clear glass4 ,white glass may be rendered translucent by a coat of white zinc and turpentine4 ,the top of a window should be as near the ceiling as practicable1 because light entering the upper portion of a room illuminates it more evenly1 and with less sharply marked shadows1 than where the windows are lower down4 ,the walls below the windows should be sloped1 in order that there may be no opportunity to use them as a resting place for material which should be placed elsewhere4 ,,fire ,,walls4 ,brick division walls should be built so as to constitute a fire wall wherever it is practicable to do so4 ,such walls should project at least three feet above the roof1 and should be capped by stone1 terra cotta1 or sheet metal4 ,they must form a complete cut-off of all combustible material1 especially at the cornices4 ,,fire ,,doors4 ,all openings in such walls must be provided with such fireproof doors as will prove reliable in time of need4 ,experience with iron doors of various forms of construction show that they have been utterly unreliable in resisting the heat of even a small fire4 ,they will warp and buckle so as to open the passageway and allow the fire to pass through the doorway into the next room4 ,a door made of wood1 completely enveloped by sheets of tinned iron1 and strongly fastened to the wall1 has proved to resist fire better than any door which can be applied to general use4 ,i have seen such doors in division walls where they had successfully resisted the flame which destroyed four stories of a building filled with combustible material1 without imposing any injury upon the door except the removal of the tin on the sheet iron2 and the doors were kept in further service without any repairs other than a coat of paint4 ,the reason for this resistance to fire is that the wood1 being a poor conductor of heat1 will not warp and buckle under heat1 and cannot burn for lack of air to support combustion4 ,a removal of the sheet metal on such a door after a fire in a mill shows that the surface of the wood is carbonized1 not burned1 reduced to charcoal1 but not to ashes4 ,many fire doors are constructed and hung in such a manner that it is doubtful whether they could withstand a fire serious enough to require their services4 ,the door should be made of two thicknesses of matched pine boards of well dried stock1 and thoroughly fastened with clinched nails4 ,it should be covered with heavy tin1 secured by hanging strips1 and the sheets lock-jointed to each other1 with the edge sheets wrapping around1 so that no seam will be left on the edge4 ,sliding doors are preferable to swinging doors for many reasons1 especially because they cannot be interfered with by objects on the floor4 ,but1 if swinging doors are used1 care should be taken that the hinges and latches are very strong1 and securely fastened directly to the walls1 and not to furring or anything in turn attached to the walls4 ,the portion of the fixtures attached to the doors must be fastened by carriage bolts1 and not by wood screws4 ,sliding on trucks is the preferable method of hanging sliding doors1 inclined two and one half inches to the foot1 and bolted to the wall4 ,the trucks should be heavy barn door hangers1 bolted to the door2 and a grooved door jamb1 of wood1 covered with tin similar to the door1 should receive it when shut4 ,a step of wood will hold the door against the wall when closed4 ,a threshold in the doorway retards fire from passing under the door1 and also prevents the flow of water from one room to another4 ,these doors are usually placed in pairs1 and sometimes an automatic sprinkler is placed between them4 ,fire doors should always be closed at night4 ,in some well ordered establishments there is a printed notice over each door directing the night watchmen to close such doors after them4 ,in a storage warehouse in ,boston1 the fire doors are connected with the watchman's electric clock system1 so that all openings of fire doors are matters of record on the dial sheet4 ,fire doors should certainly be closed at times of fire2 yet1 that such doors are open at night fires1 or left open by fleeing help at day fires1 is an old story with underwriters4 ,a simple automatic device can be used to shut such doors4 ,it consists of two round pieces of wood with a scarfed joint held by a ferrule1 forming a strut which is placed on two pins1 keeping the door open1 as other sticks have long since served like purposes4 ,the peculiarity of this arrangement is that the ferrule is not homogeneous1 but is made up of four segments of brass soldered together with the alloy fusible at #afc degrees ,fahr41 which is widely known for its use in automatic sprinklers4 ,when the solder yields1 the rod cripples1 and the door rolls down the inclined rail and shuts4 ,at any time the door can be closed by removing one end of the rod from one of the pins and allowing it to hang from the other pin4 ,,mill ,,towers4 ,because of economic reasons for preserving the space within the walls of the mill so that it may be to the greatest extent available for the best arrangement of machinery1 the stairways should be placed outside of the building4 ,such stairways should not be spiral stairways1 but should be made in short straight runs with square landings1 because in the spiral stairway the portion of the stairs near the center is of so much steeper pitch that it renders them dangerous when the help are crowding out of the mill4 ,the wear of stairs from the tread of many feet presents a difficult problem4 ,a very common practice consists in covering each tread with a thin piece of cast iron marked with diagonal scores1 and generally showing the name of the mill4 ,these treads wear out in the course of time1 but for this use they answer very well1 although somewhat slippery4 ,a wood tread gives a more secure foothold upon the stairway2 and in some instances stairs have been protected by covering the treads with boards of hard wood1 containing grooves about three-eighths of an inch deep1 and of similar width1 with a space of half an inch between them4 ,these boards are grooved on both sides and placed on the stairs4 ,after the front edge is worn1 they are turned around so as to present the other edge to the front1 and1 in course of time1 turned from the exposed side to do service in two positions on the other side4 ,in this manner these tread covers are exposed to wear in four different positions4 ,mill towers1 besides containing the stairways1 also serve other purposes1 as for cloak rooms for the help4 ,they often contain a part of the fire protective apparatus1 carrying standpipes with hydrants at each floor4 ,for this use they are easily available1 and furnish a line of retreat in case a fire spreads to an extent beyond the ability of the apparatus to cope with it4 ,these towers also furnish an excellent foundation for the elevated tank necessary for the supply of water for the fire apparatus in places unprovided with an elevated reservoir4 ,in view of the terrible and deplorable accidents which have occurred by reason of lack of proper stairway facilities at panics caused in time of fire1 ,i would repeat the words of the late ,amos ,d4 ,lockwood1 the most eminent mill engineer which this country has yet produced1 when he said to the ,new ,england ,cotton ,manufacturers' ,association1 ,you have no moral right to build a mill employing a large number of help1 with only one tower containing the stairways for exit4 ,the statute laws of several of the ,states require fire escapes2 but it is a matter of fact that they are rarely used1 because people are not often cool enough to avail themselves of that opportunity of escape4 ,i know of one instance where a number of girls jumped out of a fourth story window1 because they did not think of the stairways1 and did not dare to use the fire escape4 ,in that instance1 none of the group referred to tried to go down the stairs1 which did furnish a perfectly safe means of exit to a number of others4 ,most of the fire escapes are put up so as to conform to the letter of the law2 and in such manner that no one but a sailor or an acrobat would be likely to trust himself to them4 ,in crowded city buildings1 and in other places where the ordinary means of escape are not in duplicate1 it is essential that fire escapes should be provided2 but it is a great deal better to make a mill building so that they shall not be necessary as a matter of fact1 even if they are put up to conform to the requirements of statute law4 ,,rear ,,towers4 ,in addition to stairways1 towers are placed at the rear of the mill1 for the purpose of accommodating the elevators and sanitary arrangements4 ,it is not desirable that elevators should be boxed or surrounded with anything that would result in the construction of a flue2 but it is preferable that they pass directly through the floors1 with the openings protected by automatic hatchways which close whenever the elevator car is absent4 ,in the washroom1 etc41 in these towers1 it is desirable to protect the wood floors by means of a thin layer of asphalt4 ,,basement ,,floors4 ,there are difficulties connected with the floors on or near the ground1 by reason of the dry rot incident to such places4 ,dry rot consists in the development of fungus growth from spores existing in the wood1 and waiting only the proper conditions for their germination4 ,the best condition for this germination is the exposure to a slight degree of warmth and dampness4 ,there have been many methods of applying antiseptic processes for the preservation of wood2 but1 irrespective of their varying degrees of merit1 they have not come into general use on account of their cost1 odor1 and solubility in water4 ,it is necessary that wood should be freely exposed to circulation of air1 in order to preserve it under the ordinary conditions met with in buildings4 ,whenever wood is sealed up in any way by paint or varnish1 unless absolutely seasoned1 and in a condition not found in heavy merchantable timber1 dry rot is almost sure to ensue4 ,whitewash is better4 ,there has recently been an instance of a very large building in ,new ,york proving unsafe by reason of the dry rot generated in timbers which have been completely sealed up by application of plaster of ,paris outside of the wire lath and plaster originally adopted as a protection against fire4 ,wire lath and plaster is one of the best methods of protecting timber against fire2 and1 if the outside is not sealed by a plaster of stucco or some other impermeable substance1 the mortar will afford sufficient facilities for ventilation to prevent the deposition of moisture1 which will in turn generate dry rot4 ,where beams pass into walls1 ventilation should be assured by placing a board each side of the beam while the walls are being built up1 and afterward withdrawing it4 ,in the form of hollow walls referred to1 it is a common practice to run the end of the beam into the flue thus formed1 in order to secure ventilation4 ,i am well acquainted with a large mill property1 one building of which was erected a short time before the failure of the corporation1 which resulted in the whole plant remaining idle several years4 ,after the lapse of about five years this establishment was again put into operation2 but before the new mill could be safely filled with machinery1 it was necessary to remove all the beams which entered walls and to substitute for them new ones1 because the ends were so thoroughly rotted that it would have been dangerous to impose any further loads upon the floors4 ,when floors are within a few feet of the ground1 unless the site be remarkably dry1 it is essential to provide for a circulation of air1 which can be done very feasibly in a textile mill by laying drain pipe through the upper part of the underpinning1 forming a number of holes leading into this space1 and then making a flue from this space to the picker room or any other place requiring a large amount of air4 ,the fans of the picker room1 drawing their supply from underneath the building1 produce a circulation of air which keeps the timber in good condition4 ,it is supposed by some that there is a difference in the quality of timber according to the season in which it is felled1 preference being given to winter timber1 on account of the greater amount of potash and phosphoric acid which it is said to contain at that time4 ,in some parts of ,europe it is a custom to specify that the lumber should have been made from rafted timber1 on account of the action of the water in killing certain species of germs4 ,whatever may be the merits of either of these two theories1 the commercial lumber of the northern part of this country is generally felled in winter and afterward rafted4 ,the action of lime in the preservation of wood has always been attended with the most excellent results2 although not suited to places subject to the action of water1 which dissolves the lime1 leaving the timber practically in its original condition4 ,the preservative action of lime upon wood is readily shown by the admirable condition in which laths are always found4 ,i doubt if any one ever found a decayed lath in connection with plaster4 ,as an example of the action of lime as a preservative of lumber4 ,i can cite an instance of a mill in ,new ,hampshire where the basement floor was placed in #ahef1 the ledge in the cellar having been blasted out for the purpose4 ,the rock was very seamy1 and abounded in water issuing from springs or percolating from the canal supplying water to the mill4 ,the rock was blasted away to a grade two feet below the floor1 and most of the space filled up again by replacing the small pieces of stone1 so arranged as to form blind drains for the removal of any water which might find its way under the floor4 ,toward the top of this filling1 finer stones were used1 then about three inches of gravel1 which was covered with two inches of sand and lime4 ,two years ago ,i was at this mill when some alterations requiring the removal of the floor were in progress1 and found that the lumber was still in good1 sound condition1 except for a superficial decay on the under side of the floor plank4 ,but there are frequent instances where it is necessary to place the floor directly upon the earth1 without any space or loose filling underneath it1 in order to save room1 or to secure a firm support for machinery4 ,by way of information upon what has actually been accomplished in this direction1 ,i will cite instances of three floors in such positions1 all of which have to my knowledge fulfilled the purpose for which they were designed4 ,the first instance is that of a basement floor laid twenty-one years ago1 a portion of which was made by excavating one foot below the floor1 six inches of coarse stone being filled in1 then five inches of coal tar concrete made up with coarse gravel1 and finally about one inch of fine gravel concrete4 ,before the concrete was laid1 heavy stakes were driven through the floor about three feet apart1 to which the floor timbers were nailed and leveled up4 ,the concrete was then filled in upon the floor timbers1 and thoroughly tamped and rolled out to the level of the top of the floor timbers4 ,the under side of the floor timbers was covered with hot coal tar4 ,this floor is still in good condition1 and has not needed repairs caused by the decay of the timber4 ,another portion of the floor laid at the same time and in the same manner1 with the exception that cement concrete was used in the place of the coal tar1 was entirely rotted out in ten years4 ,another floor was made in quite a similar manner4 ,all soil and loam was removed from the interior of the building2 the whole surface was brought up to the grade with a puddle of gravel and ashes2 stakes two and a half by four inches1 and thirty inches in length1 were driven down2 and nailing strips were secured to them4 ,over this puddled surface a coat of concrete eight inches thick was laid1 the top being flush with the upper surface of the nailing strips4 ,this concrete was made of pebbles about two inches in diameter1 well coated with coal tar1 and laid in place when hot4 ,it was then packed together by being tamped and rolled1 and a thin covering of the tarred sand placed upon the top1 forming a smooth1 hard surface4 ,the first floor consisted of two inches of matched spruce1 grooved on both sides1 and fitted with hard pine splines1 five-eighths by one and one-fourth inches4 ,on the top of this a hard pine #a inch floor was laid over a course of building paper4 ,another method1 which is certainly more novel than either of the others1 consists in supporting a floor upon a bed of resin4 ,the underlying earth was removed1 and replaced with spent moulding sand1 leaving trenches for the floor timbers1 which were placed upon bricks laid without mortar4 ,melted resin was poured into the space alongside and underneath the timbers4 ,the floor planks were then laid upon the timbers1 the tops of which were about half an inch above the level of the sand4 ,holes were bored into the floor plank about four feet apart1 and melted resin then poured into the holes1 so as to interpose a layer of resin underneath the floor plank and beams4 ,upon this floor a top floor of hard wood was laid in the usual manner4 ,this floor has been used for a number of years to support a large quantity of heavy machine tools1 principally planers1 without yielding or depreciation due to decay1 and has proved to be most satisfactory4 ,in some instances asphaltum or coal tar concrete floors are not covered with wood1 although it is much more agreeable for the help to stand upon wooden floors4 ,it should be remembered that all these compounds are readily softened by means of oil1 and they should be protected from oil by a coat of paint when not covered with wood2 the preferable method being to first apply a priming containing very little oil1 or a coat of shellac1 and follow with some paint mixed up with boiled linseed oil4 7,to be continued47 99 99 99 99 99 ,,the ,,mechanical ,,equivalent ,,of ,,heat4 ,,by ,,de ,,volson ,,wood1 ,,professor ,,of ,,engineering ,,in ,,stevens ,,institute ,,of ,,technology4 ,it is clearly intimated by ,mr4 ,hanssen1 in his determination of the mechanical equivalent of heat1 published in the ,scientific ,american ,supplement1 ,no4 #fdb1 ,april #ba1 #ahhh1 that his object is to determine the absolute value of this constant4 ,with his data he finds it to be #gga4hi foot pounds4 ,but the determination by direct experiment gives a larger value4 ,thus1 the most reliable experiments--those of ,joule and ,rowland--give values exceeding by several units that found by ,hanssen4 ,a committee of the ,british ,association1 appointed for this purpose1 reported in #ahgf that sixty of the most reliable of ,joule's experiments gave the mean value #ggd4a4 ,the experiments were made with water at a temperature of about #fj ,f41 according to the mercurial thermometer1 and reduced to its value at the temperature of melting ice1 according to the formula given by ,regnault for the variation of the specific heat of water at varying temperature under the constant pressure of one atmosphere4 ,according to this formula the specific heat of water increases with the temperature above the melting point of ice1 so that the equivalent would be somewhat less at #cb ,f4 than at #fj ,f4 ,it will be found in ,regnault's ,relation des ,experiences that he experimented on water at high temperatures1 but more recently ,professor ,rowland has found that the specific heat of water is greater at #dj ,f4 than at #fj ,f41 thus reversing between these limits the law given by ,regnault2 the increase1 as given by the most probable values1 being1 roughly1 about #a_/bej of its value at #fj ,f4 ,the proper correction due to this cause would make the equivalent over #ggg foot pounds1 instead of #ggd4a4 ,professor ,rowland's experiments1 when reduced to the same thermometer1 same temperature1 and same latitude as ,joule's1 agreed very nearly with those of the latter1 being about #a_/ajjj part larger2 so that the chief difference in the ultimate values consists in the reductions for temperature and latitude4 ,the force of gravity being less for the lower latitudes1 the number representing the mechanical equivalent will be greater for the latter1 since the unit pound mass must fall through a greater number of feet to equal the same work2 so that the equivalent will be greater at ,paris than at ,manchester4 ,professor ,rowland also found that the degrees on the air thermometer from #dj ,f4 upward to above #fj ,f4 exceeded those on the mercurial thermometer throughout the corresponding range1 and that from #dj to #da the degree was between #a_/aej and #a_/bjj of a degree larger on the air thermometer than on the mercurial4 ,although this fraction is too small to be observed by ordinary means1 yet1 if it exists1 it cannot be ignored if absolute values are sought4 ,regnault employed the air thermometer in his experiments1 while ,joule used the mercurial thermometer1 and if ,joule's value #ggd4a be increased by #a_/bjj of itself in order to reduce it from the equivalent of the degree on the mercurial thermometer to that on the air thermometer1 we get #ggh foot pounds1 nearly4 ,rowland found from his experiments that when reduced to the air thermometer and to the latitude of ,baltimore1 the equivalent was nearly #ghc1 subject to small residual errors4 ,nearly all writers upon this subject--except ,rankine--have considered that the mechanical equivalent of heat1 in ,british units1 was the energy necessary to raise the temperature of one pound of water from #cb ,f4 to #cc ,f41 but ,rankine defines it as the heat necessary to increase the temperature of one pound of water one degree ,fahrenheit from that of maximum density1 or from #ci ,f4 to #dj ,f4 ,for ordinary practice it is immaterial which of these definitions is used1 for the errors resulting therefrom are much less than those resulting from ordinary observations4 ,but when the value is to be determined by direct experiment at the standard temperature1 ,rankine's limits are much to be preferred2 for it is so very difficult to determine exact values by observation when the substance is near the state bordering on a change of state of aggregation1 as that of changing from water to ice4 ,observations made at about #fj ,f4 were reduced by means of ,regnault's law for the specific heat of water1 as has been stated1 which is expressed by the formula #d #i c #a ------ t ------ t#b #aje #ajg in which t denotes the temperature according to the ,centigrade scale4 ,according to this law1 the mechanical equivalent would not be #j4b of a foot pound greater at #e ,c4 7#da ,f47 than at #j ,c4 7#cb ,f472 hence1 if this law were correct1 it would make no practical difference whether the temperature were at #j ,c4 or #e ,c4 ,this law makes the computed value at #cb ,f4 about #j4ie of a foot pound less than that determined by experiment at #fj ,f42 whereas ,rowland's experiments make it greater at #dj ,f4 by more than four foot pounds1 for the air thermometer4 ,in determining a fixed value to be used for scientific purposes1 it is necessary to fix the place1 the thermometer1 and the particular degree on the thermometer4 ,the place may be known by its latitude if reduced to the level of the sea4 ,the air thermometer agrees most nearly with that of the ideally perfect gas thermometer1 while the mercurial thermometer differs very much from it in some cases4 ,thus1 ,regnault found that when the air thermometer indicated #fcj ,f4 above the melting point of ice 7or #ffb ,f471 the mercurial thermometer indicated #fea4i above the same point 7#fhc4i ,f471 a difference of #bb ,f4 ,it is apparent that the air thermometer furnishes the best standard4 ,as for the particular degree on the scale to be used for the standard1 it is apparent1 from the observations above made1 that the temperature corresponding to that at or near the maximum density of water is more desirable than that at the melting point of ice4 ,the fact1 also1 that the specific heats at constant pressure and at constant volume are the same at the point of maximum density1 as shown by theory1 is an additional argument in favor of selecting this point for the standard4 ,it thus appears that the solution of this problem1 which appears simple and very definite by ,mr4 ,hanssen's method1 becomes intricate and1 to a limited degree1 indeterminate when subjected to the refinements of direct experiment4 ,if the constants used by ,hanssen are absolutely correct1 then his result must be unquestioned2 but since physical constants are subject to certain residual errors1 one would as soon think of finding the specific heat of air at constant volume1 by using the value of the mechanical equivalent as one of the elements1 and trusting the result1 as he would to trust to the computed value of the mechanical equivalent without subjecting it to the test of a direct experiment4 ,we will1 therefore1 examine the constants used to see if they are the exact values of the quantities they represent4 ,he says they are universally accepted as correct2 and this may be true1 when used for general purposes1 and yet not be scientifically exact4 ,he uses #j4bcgg as the specific heat of air4 ,this is the value1 to four decimals1 found by ,regnault4 ,thus1 ,regnault gives for the mean value of the specific heat of air ,between -#cj ,c and #aj ,c4 #j4bcgga #j ,c #ajj ,c4 #j4bcgda #j ,c #bjj ,c4 #j4bcgea ,and we know of no reason why one of these values should be used rather than another1 except that the mean of a large range of temperatures may be more nearly correct than that of any other2 and if this reason determines our choice1 the number #j4bcge would be used instead of #j4bcgg4 ,although this difference is small1 yet the former value would have reduced his result about #j4g of a foot pound4 ,again1 he uses #j4afhf for the specific heat of air at constant volume4 ,the value of this constant has never been found to any degree of accuracy by direct experiment1 and we are still dependent upon the method established by ,la ,place and ,poisson1 according to which the constant ratio of the specific heat of a gas at constant pressure to that at constant volume is found by means of the velocity of sound in the gas4 ,the value of the ratio for air1 as found in the days of ,la ,place1 was #a4da1 and we have #j4bcgg #a4da #j4afhf1 the value used by ,clausius1 ,hanssen1 and many others4 ,but this ratio is not definitely known4 ,rankine in his later writings used #a4djh1 and ,tait in a recent work gives #a4djd1 while some experiments give less than #a4d1 and others more than #a4da4 ,an error of one foot in a thousand in determining the velocity of sound will affect the third decimal figure one or two units4 ,a small difference in the assumed weight of a cubic foot of air also affects the result4 ,m4 ,hanssen gives #j4jhjgdc pound as the weight at #cb ,f4 under the pressure of one atmosphere2 while ,rankine gives #j4jhjgbh pound4 ,in my own computations ,i use #a4djf as a more probable value of the constant sought4 ,this will give for the specific heat of air at constant pressure #j4bcge #a4djf #j4afhi ,this is only #j4jjjc of a unit greater than the value used by ,hanssen1 but it would have given him nearly #gge1 instead of #gga4hi4 ,again1 he uses #dia4d ,f4 for the absolute temperature of melting ice4 ,the exact value of this constant is unknown2 but the mean value as determined by ,joule and ,thomson1 in their celebrated experiments with porous plugs1 was #dib4ff ,f4 ,this value would slightly change his result4 ,it will be seen from the above that a small change in the constants used may affect by several units the computed value of the mechanical equivalent4 ,i have computed it1 using #a4djf for the ratio of the specific heat of air at constant pressure to that at constant volume1 #dia4ac ,f4 as the temperature of melting ice above the zero of the air thermometer1 #bf1bad feet for the height of a homogeneous atmosphere1 and #j4bcge for the specific heat of air1 and ,i find1 by means of these constants1 #ggh4 ,if computed from the zero of the absolute scale1 #dib4ff ,f41 ,i find #ggg to the nearest integer4 ,recently ,i have used #ggh4 ,if the value given by ,rowland1 about #ghc according to the air thermometer at #ci ,f41 should prove to be correct1 it seems probable that the constant #a4djf used above would be reduced to about #a4djc1 or that the other constants must be changed by a small amount4 ,the height of the homogeneous atmosphere used above1 #bf1bad feet1 is the value used by ,rankine as deduced from ,regnault's figures1 and only one foot less than the value used by ,sir ,william ,thomson2 but the figures used by ,mr4 ,hanssen give #bf1baj feet4 ,the method above called ,hanssen's is really that of ,dr4 ,mayer 7the ,german professor71 who in #ahdb used it for determining the mechanical equivalent2 but on account of erroneous data1 the value found by him was much too small4 99 99 99 99 99 ,,economy ,,trials ,,of ,a ,,non-,,condensing ,,steam ,,engine--,,simple1 ,,compound1 ,,and ,,triple4#a ,footnote #a3 ,abstract of paper read before the ,institution of ,civil ,engineers1 ,march #ac4 ,,by ,,mr4 ,p4 ,w4 ,,willans1 ,m4,i4,c4,e4 ,the author described a series of economy trials1 non-condensing1 made with one of his central valve triple expansion engines1 with one crank1 having three cylinders in line4 ,by removing one or both of the upper pistons1 the engine could be easily changed into a compound or into a simple engine at pleasure4 ,distinct groups of trials were thus carried out under conditions very favorable to a satisfactory comparison of results4 ,no jackets were used1 and no addition had1 therefore1 to be made to the figures given for feed water consumption on that account4 ,most of the trials were conducted by the author1 but check trials were made by ,mr4 ,mac,farlane ,gray1 ,prof4 ,kennedy1 ,mr4 ,druitt ,halpin1 ,professor ,unwin1 and ,mr4 ,wilson ,hartnell4 ,the work theoretically due from a given quantity of steam at given pressure1 exhausting into the atmosphere1 was first considered4 ,by a formula deduced from the theta phi diagram of ,mr4 ,mac,farlane ,gray1 which agreed in results with the less simple formulas of ,rankine and ,clausius1 the pound weight of steam of various pressures required theoretically per indicated horse power were ascertained4 7,see annexed table47 ,a description was then given of the main series of trials1 all at four hundred revolutions per minute1 of the appliances used1 and of the means taken to insure accuracy4 ,a few of the results were embodied in the table4 ,the missing quantity of feed water at cut off1 which1 in the simple trials1 rose from #aa4g per cent4 at #dj lb4 absolute pressure to nearly #cj per cent4 at #aaj lb4 and at #ij lb4 was #bd4h per cent41 was at #ij lb4 only #e per cent4 in the compound trials4 ,in the latter1 at #afj lb41 it increased to #ag per cent41 but1 on repeating the trial with triple expansion1 it fell to #e4df per cent4 or to #d4dc per cent4 in another trial not included in the table4 ,on the other hand1 from the greater loss in passages1 etc41 the compound engine must always give a smaller diagram1 considered with reference to the steam present at cut-off1 than a simple engine1 and a triple a smaller diagram than a compound engine4 ,nevertheless1 even at #hj lb4 absolute pressure1 the compound engine had considerable advantage1 not only from lessened initial condensation1 but from smaller loss from clearances1 and from reducing both the amount of leakage and the loss resulting from it4 ,these gains became more apparent with increasing wear4 ,the greater surface in a compound engine had not the injurious effect sometimes attributed to it1 and the author showed how much less the theoretical diagram was reduced by the two small areas taken out of it in a compound engine than by the single large area abstracted in a simple engine4 ,the trials completely confirmed the view that the compound engine owed its superiority to reduced range of temperature4 ,at the unavoidably restricted pressures of the triple trials1 the losses due to the new set of passages1 etc41 almost neutralized the saving in initial condensation1 but with increased pressure--say to #bjj lb4 absolute--there would evidently be considerable economy4 ,the figures of these trials showed that the loss of pressure due to passages was far greater with high than with low pressure steam1 and that pipes and passages should be proportioned with reference to the weight of steam passing1 and not for a particular velocity merely4 ,the author described a series of calorimetric tests upon a large scale 7usually with over two tons of water71 the results of which were stated to be very consistent4 ,after comparing the dates of initial condensation in cases where the density of steam1 the area of exposed surface1 and the range of temperature were all variables1 with other cases 7#a7 where the density was constant and 7#b7 where the surface was constant1 the author concluded that1 at four hundred revolutions per minute1 the amount of initial condensation depended chiefly on the range of temperature in the cylinder1 and not upon the density of the steam or upon the extent of surface1 and that its cause was probably the alternate heating and cooling of a small body of water retained in the cylinder4 ,the effect of water1 intentionally introduced into the air cushion cylinder1 corroborated the author's views1 and he showed how small a quantity of water retained in the cylinder would account for the effects observed4 ,at lower speeds surface might have more influence4 ,the favorable economical effect of high rotative speed1 per se1 was very apparent4 ,in a trial with a compound engine1 with #acj lb4 absolute pressure1 the missing quantity at cut-off rose from #aa4g per cent4 at #dje revolutions to #bi4ff per cent4 at #acj revolutions1 the consumption of feed water increasing from #bj4ce lb4 to #bc4fg lb4 ,this saving of #ad per cent4 was due solely to increase of speed4 ,similar trials had been made with a simple engine4 ,in one simple trial at slow speed the missing quantity rose to #dd4e per cent4 of the whole feed water4 ---------------------------------------- ---------------------------------------- ------------------ ,intended mean admission pressure ,lb4 #dj #ij #aaj #acj #aej #afj #agj ---------------------------------------- ---------------------------------------- -------------- ,simple1 ,compound1 or ,triple4 ,s4 ,s4 ,c4 ,s4 ,c4 ,c4 ,c4 ,t4 ,c4 ,t4 ,t4 ,actual mean admission pressure ,lb4#dj4hh #ib4fehg4edajf4c #aji4c #acj4f #adi4i #aea4i #aeh4e #aeh4a #agb4e ,percentage ratio of actual mean pressure1 referred to low pressure piston1 to theoretical mean pressure #ih4b #ajj #ia4c #ajj4g #id4h #id4b #id4f #hd4ed #ie4i #he4c #he4b ,indicated horse power #af4ea #ca4fabh4ad #cc4e #cc #cf4ca #ch4ei #ce4fi #ci4ee #ce4ef #ch4de ---------------------------------------- ---------------------------------------- -------------- ,feed water actually used per indicated ,h4,p4,h4-- ,simple ,lb4#db4gf #bf4hi 444 #bf 444 444 444 444 444 444 444 ,compound ,lb4 444 444 #cd4af 444 #ba4cg #bj4ce #ai4de 444 #ai4ai 444 444 ,triple ,lb4 444 444 444 444 444 444 444 #ai4fh 444 #ai4ai #ah4de ,steam required theoretically per #a ,h4,p4,h4 ,lb4#cd4fg #ai4bdai4hf #ag4i #ag4fe #af4be #ae4bc #ae4af #ad4hg #ad4i #ad4cf ,percentage efficiency #ha4a #ga4e #hb4b #fh4h #hb4e #hj #gh4c #gg #gg4d #gg4f #gg4h ---------------------------------------- ---------------------------------------- -------------- ,percentage of feed water missing at cut off in high pressure cylinder 444 444 444 444 444 444 444 #e4cc 444 #f4hd #e4ja ,ditto high pressure cylinder 444 444 #e 444 #i4e #aa4g #ae4a #ad4hd #ag #ab4jf #ae4cc ,ditto low pressure cylinder #aa4g #bd4h #ae4b #bi4ef #af4be #ai4a #bj4f #bb4ab #ba4c #bb4aa #bd4ba ,percentage of feed water missing at end of stroke in low pressure cylinder #aj4d #ah4hcad4be #ba4ec #af4ei #ag4ee #bj4fi #ah4ja #ai4ee #ah4ha #ai4be ---------------------------------------- ---------------------------------------- -------------- ,the author compared a series of compound trials1 at different powers1 with #acj lb4 absolute pressure1 and various ratios of expansion1 with a series giving approximately the same powers at a constant ratio of expansion1 but with varying pressures1 being practically a trial of automatic expansion against throttling4 ,starting with #dj indicated horse power1 #acj lb4 absolute pressure1 four expansions1 and a consumption of #bj4ge lb4 of water1 the plan of varying the expansion1 as compared with throttling1 showed a gain of about #g per cent4 at #cj indicated horse power1 but of a very small percentage when below half power4 ,if the engine had an ordinary slide valve1 the greater friction1 added to irregular motion1 would probably neutralize the saving1 while if the engine were one in which initial condensation assumed more usual proportions1 the gain would be probably on the side of variable pressure4 ,even as it was1 the diagrams showed that the missing quantity became enormously large as the expansion increased4 ,judging only by the feed water accounted for by the indicator1 the automatic engine appeared greatly the more economical1 but actual measurement of the feed water disproved this4 ,the position of the automatic engine was1 however1 relatively more favorable when simple than when compound4 ,in conclusion1 the author referred to a trial with a condensing engine1 at #agj lb4 absolute pressure1 in which the feed water used was #ae4a lb41 a result evidently capable of further improvement1 and to an efficiency trial of a combined central valve engine and ,siemens' dynamo1 made for the ,admiralty1 at various powers4 ,at the highest power the ratio of external electrical horse power to indicated horse power in the engine was #hb4c per cent4 ,taking the thermo-dynamic efficiency of the engine at #hj per cent41 that of the combined apparatus would be nearly #ff per cent4 99 99 99 99 99 ,,railway ,,bridge ,,at ,,lachine4 ,the subject of our large illustration this week is a large steel bridge carrying the ,central ,pacific ,railway over the ,st4 ,lawrence ,river at ,lachine1 near ,montreal4 ,the main features of this really magnificent structure are the two great channel spans1 each #djh feet long4 ,it will be noticed that the design combines1 in a very ingenious manner1 an upper and a lower deck structure1 the railway track being laid on the top of the girders forming the side spans1 and on the lower flanges of the channel spans1 which are crossed by continuous girders1 #ge feet deep1 over the central pier1 and supported by brackets as shown4 ,the upper of our two engravings shows the method of constructing the principal spans1 which were built outward from the side piers1 while the work on the center pier was extended on each side to meet4 ,it was built at the works of the ,dominion ,bridge ,company1 ,montreal1 from the design of ,mr4 ,c4 ,shaler ,smith1 the well-known ,american bridge engineer4--,engineering4 ,illustration 99 99 99 99 99 ,,improved ,,screw ,,propeller4 ,while the last few years have seen great advances made in the designs of steamships and of their engines1 little or nothing has been done in the way of improving the screw propeller4 ,as a general rule it would appear to be taken for granted that no radical improvement could be made in the form of the propeller1 although various metals have been introduced in its manufacture with the view of increasing its efficiency4 ,for sea-going steamers1 however1 the shape remains the same1 the variation chiefly relating to the number of blades employed4 ,a striking departure from ordinary practice1 however1 has of late been made by ,mr4 ,b4 ,dickinson1 who has invented a screw propeller which1 on practical trial1 has given an efficiency far in advance of the ordinary screw4 ,this new propeller we illustrate here in ,figs4 ,c and ,d1 while ,fig4 ,a shows an ordinary propeller4 ,the ,dickinson propeller illustrated has six blades1 giving a surface of #cj square feet2 it is right handed1 and has pitch of #ae ft4 and a diameter of #aj ft4 #f in4 ,the ordinary screw propeller shown at ,fig4 ,a is right handed and two bladed1 with a pitch at the boss of #ac ft4 #f in4 and at the tip of #ae ft4 ,it has a diameter of #aj ft4 #i in4 and #cb square ft4 of surface4 ,the projected area looking forward is #bb square ft4 and the projected area looking athwartship #bb4hd square feet4 ,the most graphic way of illustrating the principle of ,mr4 ,dickinson's propeller is to take a two bladed propeller of the ordinary type as shown at ,fig4 ,a in the annexed cuts1 and divide into three sections as in ,fig4 ,b1 then move section ,no4 #a to the line position on the shaft of ,no4 #c1 and ,no4 #c to that of ,no4 #a1 ,no4 #b remaining stationary4 ,the effect of this interchange will be that 7having regard to the circle of rotation7 ,no4 #c1 the rearmost section1 will rotate in advance of ,no4 #b1 and ,no4 #b in advance of ,no4 #a 7see ,fig4 ,c74 ,by this arrangement the water operated on escapes freely astern from every blade--that from ,no4 #a passing in the wake of ,no4 #b1 while that from ,nos4 #b and #a passes in the wake of ,no4 #c4 ,fig4 ,d represents the blades with a wider spread as practically used4 ,the advantages claimed by ,mr4 ,dickinson for his propeller1 and which are sufficiently important to be given in detail1 are3 ,illustration3 ,figs4 ,a-,d4 #a4 ,that the blades of each section1 when the vessel is in motion1 necessarily cut solid1 undisturbed water1 each blade operating upon precisely the same quantity of water as an individual broad blade would do1 though1 of course1 it parts with it in one-third of the time4 #b4 ,that each sectional blade exerts the equivalent efficiency of the first or entering third portion of the breadth of an ordinary propeller blade1 and that consequently the combined sections have greater effective power4 ,it is now regarded by experts as an ascertained fact that the after or trailing portion of the broad blade is relatively non-effective as compared with the forward or entering portion4 #c4 ,when three blades are fitted1 the spent water from ,no4 #b being delivered immediately in the wake of ,no4 #c1 and that from ,no4 #a in the wake of ,no4 #b1 has the effect of destroying or reducing to a minimum the back draught of sections ,nos4 #b and #c1 ,no4 #a alone being subject to this drawback4 ,this is of greater importance than might at first thought appear1 as in cases where there are three or four blades revolving in one plane1 the water is drawn after the retreating blade1 lessening the resistance to the face of the advancing one4 #d4 ,that by the subdivision of the blades1 as arranged spirally1 the water passing through within the radius of the propeller has its resisting capacity more thoroughly worked out than is possible with any propeller whose blades are all on the same plane4 ,this view is confirmed by the visibly increased rotation of the water in the wake of the vessel4 #e4 ,that by broadening the blades or increasing the number of sections1 the diameter of the propeller may be proportionately diminished without the sacrifice of engine power4 ,this is often desirable with vessels of light draught1 the complete immersion of the screw being at all times necessary to avoid waste of power4 #f4 ,the propeller being made and fitted on the shaft in sections1 all that is necessary in case of accident is to replace the broken section4 ,this in many cases could be done afloat4 #g4 ,the blades being arranged to take their water at different planes1 there is the greater certainty of one or other of the sections operating upon what is termed the water of friction4 ,this is considered an advantage4 #h4 ,where it is desirable1 the blades of the different sections can be made of varying breadth or pitch4 #i4 ,the principle of division into two or more sections applies equally to two1 three1 or four bladed ordinary propellers4 #aj4 ,the adoption of this principle does not entail any alteration or enlargement of the screw space or bay as usually provided4 #aa4 ,as a consequence of the freedom and rapidity with which the water operated upon escapes from the narrow blades1 the depression at the stern of the vessel caused by the action of the ordinary propeller is greatly reduced4 #ab4 ,the vibration caused by this propeller is so slight as to be hardly noticeable1 thereby effecting a saving in the wear and tear of the engine and machinery4 ,this may also be a consideration in promoting the comfort of passengers4 ,from a practical and working point of view we take ,mr4 ,dickinson's chief claims to be1 in the first place1 the yielding of a greater speed per power employed1 or an economy in obtaining an equal speed2 in the second1 increased1 rapidity in maneuvering and stopping a vessel2 and in the third1 a reduction of vibration4 ,in order to put these claims to a practical and reliable comparative test1 ,messrs4 ,weatherley1 ,mead ,hussey1 of ,saint ,dunstan's ,hill1 ,london1 placed at the inventor's disposal two of their new steamers1 the ,herongate and the ,belle of ,dunkerque4 ,these are in every respect sister boats1 and were built in #ahhg by ,messrs4 ,short ,brothers1 and engined by ,mr4 ,john ,dickinson1 of ,sunderland4 ,the ,herongate was fitted about four months ago with the largest propeller yet made on ,mr4 ,b4 ,dickinson's principle1 the ,belle of ,dunkerque having an ordinary four-bladed propeller of the latest improved type4 ,every precaution was taken to place the two vessels on the same footing for the purpose of a comparative test1 which was recently carried out4 ,both vessels previously to the trial were placed on the gridiron1 cleaned and painted1 their boilers opened out and scaled1 their steam gauges independently tested1 and both vessels loaded with a similar cargo of pitch1 the only difference being that the ,herongate carried #aa tons more dead weight and had one inch more mean draught than the ,belle of ,dunkerque1 while the former had been running continuously for nine months against the latter's two and a half months4 ,on the day of the trial the vessels were lying in the ,lower ,hope reach1 and it was decided to run them over the measured mile there with equal pressure of steam4 ,the order of running having been arranged1 the ,herongate got under way first1 the ,belle of ,dunkerque following over the same course4 ,steaming down against tide1 the ,herongate is said to have come round with remarkable ease and rapidity1 and in turning on either helm1 whether with or against tide1 to have shown a decided advantage4 ,equally manifest1 it is stated1 was the superiority shown in bringing up the vessel by reversing1 when running at full speed1 thus confirming the very favorable reports previously received by the owners from their captains since the ,dickinson propeller was fitted to the ,herongate4 ,those who were on board her state that the vibration was scarcely noticeable4 ,from a statement submitted to us it is clear that the ,herongate had the turn of the scale against her in dead weight and draught1 vacuum1 and diagrams taken1 but notwithstanding 7making allowance for one faulty run due to the variations in tide7 she appears to have more than held her own in the matter of speed1 with a saving of #d and #c revolutions per minute at #adj lb4 and #afj lb4 steam pressure respectively4 ,this is further confirmed by the results of a run made after the experiments were concluded1 the two vessels being placed in line1 and fairly started for a half hour's run over the flood with #aej lb4 steam pressure4 ,at the expiration of that time the ,herongate was judged to be leading by at least half a length1 her revolutions being #gf1 as against #hj in the ,belle of ,dunkerque4 ,it was agreed by all present at these trials that the propeller had realized in full the three main working advantages claimed for it4 ,this being the first ,dickinson propeller fitted to a sea-going vessel of this size1 it is quite within the limits of possibility that the present results may be improved upon in further practice4 ,in any case we can but regard this propeller as a distinct and original departure in marine propulsion1 and we congratulate ,mr4 ,dickinson on his present success and promising future4 ,messrs4 ,weatherley1 ,mead ,hussey also deserve credit for their discernment1 and for the spirited manner in which they have taken up ,mr4 ,dickinson's ingenious invention4 ,we understand that they are so satisfied with the results that they intend having one of their larger ocean-going steamers fitted with the ,dickinson propeller4--,iron4 99 99 99 99 99 ,,improved ,,dobby4 ,illustration ,at the ,manchester ,royal ,jubilee ,exhibition1 ,messrs4 ,butterworth ,dickinson1 ,burnley1 showed ,catlow's patent dobby1 which is illustrated above1 as applied to a strong calico loom4 ,this dobby is a double lift one1 thus obtaining a wide shed1 and the use of two lattice barrels connected by gearing so that they both revolve in the same direction4 ,the jack lever is attached to the vertical levers1 the top and bottom catches being worked respectively by the two barrels1 and connected with the ends of the levers4 ,to each of these catches a light blade spring is attached1 which insures them being sprung upon the top of the knife1 and thereby obtaining a certain lift4 ,a series of wooden jacks or levers are employed1 so as to give a varying lift to the front and back healds1 in this way keeping the yarn in even tension1 and preventing slack sheds4 ,the healds are drawn down by means of a series of levers adjoining one another1 and worked by means of a rocking bar driven from the tappet shaft4 ,when the shed is being formed1 the jacks are pushed down until it is fully open1 and the warp is thus drawn down with the same certainty as the upward movement is made4--,industries4 99 99 99 99 99 ,,united ,,states ,,consular ,,reports4 ,,special ,,issue ,,no4 #aj4 ,,sulphur ,,mines ,,in ,,sicily4 ,,by ,,phillip ,,carroll1 ,u4 ,s4 ,,consul1 ,,palermo4 ,sulphur1 or brimstone1 is a hard1 brittle substance of various colors1 from brilliant yellow to dark brown1 without smell when cool1 of a mild taste1 and burns with a pale blue flame1 emitting pungent and suffocating fumes4 ,its specific gravity is from #a4i to #b4a4 ,sulphur exists more or less in all known countries1 but the island of ,sicily1 it is thought1 is the only place where it is produced on a large scale1 and consequently that island appears to command the market4 ,small quantities have been found in the north of ,italy1 the ,grecian ,archipelago1 ,russia1 ,austria1 ,poland1 ,france1 ,spain1 eastern shores of ,egypt1 ,tunis1 ,iceland1 ,brazil1 ,central ,america1 and the ,united ,states4 ,large quantities are said to exist in various countries of ,asia1 but it is understood to be impracticable to utilize the same1 consequent upon the distance from any commercial port and the absence of rail or other roads4 ,sulphur is of two kinds1 one of which is of volcanic emanation1 the other being closely allied to sedimentary rocks4 ,the latter is found in ,sicily1 on the southern and central portions of the island4 ,mount ,etna1 situated in the east1 seems to exert no influence in the formation of brimstone4 ,there are various hypotheses relative to its natural formation4 ,dr4 ,philip ,swarzenburg attributes it to the emanations of sulphur vapor expelled from metallic matter existing in the earth1 consequent upon the fire in the latter1 while ,professors ,hoffman and ,bischoff ascribe it to the decomposition of sulphureted hydrogen4 ,hoffman believes the sulphureted hydrogen must have passed through the fissures of stratified rocks1 but ,bischoff is of opinion that the sulphureted hydrogen must have been the result of the decomposition of sulphate of lime in the presence of organic matter4 ,the theory of others is that sulphur owes its origin to the combination of lacustrine deposits with vegetable matter1 and others again suppose that it is due to the action of the sea upon animal remains4 ,the huge banks of rock salt often met with in the vicinity of sulphur mines1 and which in some places stretch for a distance of several miles1 seem to indicate that the sea has worked its way into the subsoil4 ,fish and insects1 which are frequently found in strata of tripoli1 which lie under sulphur beds1 induce the belief that lakes formerly existed in ,sicily4 ,the following is a list of the various strata which form part of the crust of the earth in ,sicily1 according to ,professor ,mottura1 an ,italian geologist3 ,pliocene4--,sandstone2 coarse calcareous rock2 marl4 ,upper ,miocene4--,calcareous marl2 gypsum1 etc42 sulphur embedded in calcareous limestone2 silicious limestone2 tripoli1 containing fossils of fish1 insects' eggs1 etc4 ,middle ,miocene4--,sandstone containing quartz1 intercalated with marl of a saltish taste4 ,lower ,miocene4--,rock salt2 blue marl1 containing petroleum and bitumen2 flintstone2 ferruginous clay1 mixed with aragonite and bituminous schists2 ferruginous and silicious sandstone4 ,eocene4--,limestone1 containing diaspores and shells4 ,at times one or another of the strata disappears1 while the order of some is slightly reversed on account of the broken state of the crust4 ,upon the whole1 however1 the above has been generally observed in the various mines by the author referred to4 ,sulphur mines have been operated in ,sicily over three hundred years1 but until the year #ahbj its exportation was confined to narrow limits4 ,at present the number of mines existing in ,sicily is about three hundred1 nearly two hundred of which1 being operated on credit1 are1 it is understood1 destined to an early demise4 ,it is said that there are about #cj1jjj1jjj tons of sulphur in ,sicily at present1 and that the annual production amounts to about #djj1jjj tons4 ,if this should be true1 taking the foregoing as a basis1 the supply will become exhausted in about seventy-five years4 ,in #ahai a law was passed in ,italy1 which is still in force1 governing mining in ,sicily1 which provides that should a land owner discover ore in his property he would be the owner thereof1 and should have the right to mine1 operate1 or rent the property to others for that purpose1 but if he should decline to operate his mines or to rent them to others to be operated1 the state would rent them on its own account4 ,royalties vary from #ab to #de per cent4 ,they are paid according to the quality of the ore and the facilities for producing sulphur2 #be per cent4 may1 however1 be taken as an average4 ,there is a land tax of #cf per cent4 of the net income1 which is usually paid by the owners and lessees of the mines1 in proportion to the quantity of sulphur which they produce4 ,the export duty is #aj lire per ton4 ,all mines are inspected by government officials once a year1 and the owners are required to furnish the state with plans of the works and their progress1 with a view to insure the safety of the workmen and to ascertain the extent of the property4 ,those who rent their mines receive from #aj to #dj per cent4 of the sulphur produced4 ,leases are valid for such period as the contracting parties may stipulate therein4 ,the general limit1 however1 is nine years4 ,the average lease is #be per cent41 #dj per cent4 being paid only when the mines are very favorably situated and the production good4 ,some lessees prefer paying a considerable sum in cash in advance1 at the beginning of the term of the lease1 and giving #ae or #bj per cent4 in sulphur annually thereafter1 instead of a higher percentage4 ,the external indications of the presence of sulphur are the appearance of gypsum and sulphurous springs4 ,these are indubitable signs of the presence of sulphur1 and when discovered the process resorted to here1 in order to reach the sulphur1 is to bore a hole sufficiently large to admit a man1 after which steps are constructed in the passage in order to facilitate the workmen in going to and fro4 ,these steps extend across the passage1 and are about #be centimeters high and #ce broad4 ,the inclination of the holes or passages varies from #cj to #ej degrees4 ,upon attaining the depth of several meters water is often met with1 and in such considerable quantity that it is impossible to proceed4 ,hence it becomes necessary to either pump the water out or retreat in order to bore elsewhere4 ,it is often necessary to bore several passages in order to discover the ore or seam of sulphur4 ,when1 however1 it has been discovered the passages are made to follow its direction1 whether upward or downward4 ,as the direction of seams is in most cases irregular1 that of the passages or galleries is likewise4 ,where the ore is rich and the matrix yielding1 the miners break it by means of pick-axes and pikes1 but when such is not the case gunpowder is resorted to1 the ore in this case being carried to the surface by boys4 ,the miners detach the ore from the surrounding material1 and the cavities which ensue in consequence assume the appearance of vast caves1 which are here and there supported by pillars of rock and ore in order to keep them from falling or giving way4 ,in order to strengthen the galleries sterile rock is piled upon each side and cemented with gypsum4 ,in extensive mines1 however1 these supports and linings are too weak1 and not infrequently1 as a result1 the galleries and caverns give way1 occasionally causing considerable havoc among the miners4 ,sulphur is found from the surface to a depth of #aej meters4 ,the difficulties met with in operating mines are numerous1 and among the greatest in this category are water1 land slides1 irregularity of seam1 deleterious gases1 hardness of rocks and matrices4 ,of these difficulties1 water is the most frequently met with4 ,indeed1 it is always present1 and renders the constant use of pumps necessary4 ,at one time miners were allowed to dig where they pleased so long as sulphur was extracted1 the consequence being that in groups of mines1 the extent and direction of which being unknown to their respective owners1 one mine often fell into or upon another1 thus causing destruction to life and property4 ,it was largely for this reason1 it is understood1 that the government determined to require owners and lessees of mines to furnish plans thereof to proper authority1 and directed that official inspection of the mines should be made at stated periods4 ,in order to comply with the decree of the government it became necessary to employ mining engineers to draw the plans1 etc41 and those employed were generally foreigners4 ,in the system of excavation described no steam power is employed4 ,pumping is performed by means of primitive wooden hand pumps1 and when sufficient ore has been collected it is conveyed on the backs of boys to the surface--a slow1 costly1 and difficult procedure4 ,this system may1 however1 be suitable to small mines1 but in large mines there is no economy in hand labor2 indeed1 much is lost in time and expense by it4 ,for this reason steam has been introduced into the larger and more important mines4 ,the machinery employed is a hoisting apparatus1 with a drum1 around which a coil is wound1 with the object of hoisting and lowering trucks in vertical shafts4 ,steam pumps serve to extract the water4 ,the force of the hoisting apparatus varies from #ae to #ej horse power4 ,the fuel consumed is ,english and ,french coal1 the former being preferred1 as it engenders greater heat4 ,the cost of a ton of coal at the wharf is #d4dj1 whereas in the interior of the island it costs about #aj4 ,the shafts or pits are made in the ordinary way1 great care being taken in lining them with masonry in order to guard against land slides4 ,in level portions of the country vertical shafts are preferred1 but where the mine is situated upon a hill a debouch may often be found below the sulphur seam1 when an inclined plane is preferred1 the ore being placed in trucks and allowed to run down the plane on rails until it reaches the exterior of the mine1 where it suddenly and violently stops1 and as a result the trucks are emptied of their load1 when they are drawn up the plane to be refilled2 and thus the process goes on indefinitely4 ,in these mines a gutter is made in the inclined plane which carries off the water1 thus dispensing with the necessity of a pump and the requisites to operate it4 ,the galleries and inclined shafts are lined with beams of pine or larch1 which are brought hither from ,sardinia1 as ,sicily possesses very little timber4 ,the mines are illuminated by means of iron oil lamps1 the wicks of which are exposed4 ,the lamps are imported from ,germany4 ,in certain cases an earthenware lamp1 made on the island1 and said to be a facsimile of those used by the ,phoenicians1 is employed4 ,this lamp is made in the shape of a small bowl4 ,it is filled with oil and a wick inserted1 which hangs or extends outward1 and is thus ignited1 the flame being exposed to the air4 ,safety lamps are unknown1 and those described are generally secure4 ,few explosions take place--only when confined carbonic hydrogen is met with in considerable quantities1 and when the ventilation is not good4 ,in this case the mine is easily ignited1 and once on fire may burn for years4 ,the only practical expedient for extinguishing the fire is to close all inlets and outlets in order to shut off the air4 ,this1 however1 is difficult and takes time4 ,notwithstanding the closing of communications1 the gases escape through the fissures and openings which obtain everywhere1 and the ingress of air makes it next to impossible to extinguish the fire2 hence it burns indefinitely or until the mine is exhausted4 ,occasionally the burning of a mine results beneficially to its owners1 in that it dispenses with the necessity of smelting1 and produces natural1 refined sulphur4 ,galleries in extent are usually #a4bj by #a4hj meters1 and when ore is not found and it becomes necessary to extend the galleries1 laborers are paid in accordance with the progress they may make and the character of the rock1 earth1 etc41 through which it may be necessary to cut1 as follows3 ,silicious limestone1 #fj lire per meter2 daily progress1 #j4bj meter4 ,gypsum1 #ej lire per meter2 daily progress1 #j4cj meter4 ,marl1 #cj lire per meter2 daily progress1 #j4ej meter4 ,clay1 #ae lire per meter2 daily progress1 #a meter4 ,laborers working in the ore are paid #d4cj lire per ton4 ,this includes digging1 extracting1 and illumination4 ,in some mines1 however1 the laborers are paid when the sulphur is fused and ready for exportation4 ,one ton of sulphur1 or its equivalent 7say from #dj to #ej lire71 is the amount generally paid4 ,in mines where this system obtains the administration is only responsible for their maintenance4 ,each miner produces on an average about #a tons of ore daily1 and when the works are not more than #dj meters in depth he employs one boy to assist him1 two boys when they reach #fj meters1 and three when under #ajj meters4 ,these boys are from seven to sixteen years of age1 and are paid from #j4he to #a4ej lire per day by the miner who employs them4 ,they carry from #a1jjj to #a1ejj pounds of ore daily1 or in from six to eight hours4 ,the food consumed by miners is very meager1 and consists of bread1 oil1 wine1 or water2 occasionally cheese1 macaroni1 and vegetables are added to the above4 ,mining laborers generally can neither read nor write1 and when employed in mines distant from habitations or towns1 live and sleep therein1 or in the open air1 depending on the season or the weather4 ,in a few mines the laborers are1 however1 provided with suitable dwelling places1 and a relief fund is in existence for the succor of the families of those who die in the service4 ,this fund is greatly opposed by the miners1 from whose wages from #a to #b per cent4 is deducted for its maintenance4 ,in the absence of a fund of this character1 the sick or infirm are abandoned by their companions and left to die4 ,generally miners are inoffensive when fairly dealt with4 ,they are said to be indolent and dishonest as a rule4 ,the managers of mines receive from #c1jjj to #e1jjj lire per annum2 chief miners from #a1ejj to #b1ejj lire2 surveyors1 #gjj to #a1jjj lire2 and weighers and clerks1 from #a1jjj to #b1jjj lire per annum4 ,the total number of mining laborers in ,sicily is estimated at about #be1jjj4 ,the ore for fusion of the first grade as to yield contains from #bj to #be per cent4 of sulphur1 that of the second grade from #ae to #bj per cent41 and of the third grade #aj to #ae per cent4 ,the usual means adopted for extracting sulphur from the ore is heat1 which attains the height of #djj degrees ,centigrade1 smelting with the kiln1 which in ,sicilian dialect is called a calcarone4 ,the calcarone is capable of smelting several thousand tons of ore at a time and is operated in the open air4 ,part of the sulphur is burned in the process of smelting in order to liquefy the remainder4 ,calcaroni are situated as closely to the mouth of a shaft as possible1 and if practicable on the side of a hill1 in order that when the process of smelting is complete1 the sulphur may run down the hill in channels prepared for the purpose4 ,the shop of a calcarone is circular and the floor has an inclination of from #aj to #ae degrees4 ,a design of a calcarone is herewith inclosed4 ,the circular wall is made of rude stone work1 cemented together with gypsum4 ,the thickness of the wall at the back is #j4ej meter1 and from this it gradually becomes thicker until in front1 where it is #a meter1 when the diameter is to be #aj meters4 ,in front of the thickest part of the wall an opening is left1 measuring #a4bj meters high and #j4be meter broad4 ,through this opening the liquid sulphur flows4 ,upon each side of this opening two walls are built at right angles with the circular wall1 in order to strengthen the front of the kiln4 ,these walls are #hj centimeters thick each and are roofed4 ,a door is hinged to these walls1 thus forming a small room in front of each kiln in which the keeper thereof resides from the commencement to the termination of the flow of sulphur4 ,the inclined floor of the kiln is made of stone work and is covered with ginesi1 the name given to the refuse of a former process of smelting4 ,the stone work is #bj centimeters thick1 and the ginesi covering #be centimeters1 which gradually becomes thicker as it approaches its lowest extremity4 ,the front part of the circular wall is #c4ej meters high and the back #a4hj meters4 ,the interior of the wall is plastered with gypsum in order to render it impermeable4 ,the cost of a calcarone of about #ejj tons capacity is #hjj lire4 ,the capacity varies from #dj to #e1jjj tons1 or more1 depending upon circumstances4 ,if a mine is enabled to smelt the whole year round1 the smaller calcaroni1 being more easily managed1 are preferred2 the inverse is the case as to the larger calcaroni1 when this is impracticable4 ,when a calcarone is situated within #ajj meters of a cereal farm1 its operation is prohibited by law during the summer1 lest the fumes of the sulphur should destroy the crop4 ,when1 however1 the distance is greater from the farm or farms than #ajj meters1 smelting is permitted2 but should any damage ensue to the crops as a result of the fumes1 the owners of the calcaroni are required to liquidate it4 ,therefore the mines which are favorably situated smelt the entire year1 and employ calcaroni of from #dj to #ejj tons1 as there is less risk of a process failing1 which occasionally happens1 and for the reason that the ore can be smelted as soon as it is extracted2 whereas1 when kilns or calcaroni are situated within or adjacent to the limit adverted to1 they can only be operated five or six months in the year1 consequent upon which the ore is necessarily stacked up all through the summer or until such time as smelting may be commenced without endangering the crops1 when it becomes necessary to use calcaroni whose capacity amounts to several thousand tons4 ,as intimated1 these large calcaroni are not so manageable as those of smaller dimensions1 and as a result many thousands of tons of sulphur are lost in the process of smelting1 besides perhaps the loss of an entire year in labor4 ,again1 the ore deteriorates or depreciates when long exposed to the air and rain1 all of which1 when practicable1 render the kilns or calcaroni of the smaller capacity more advantageous and lucrative to those operating sulphur mines in ,sicily4 ,smelting with a calcarone of #bjj tons capacity consumes thirty days1 one of #hjj tons #fj days1 and with a calcarone of #b1jjj tons capacity from #ij to #abj days are consumed4 ,in loading or filling the calcaroni1 the larger blocks of ore are placed at the bottom as well as against the mouth1 in order to keep the lower part of the kiln as cool as possible with a view of preventing the liquid sulphur from becoming ignited as it passes down to where it makes its exit1 etc4 ,the blocks of ore thus first placed in position are1 for obvious reasons1 the most sterile4 ,after the foundation is thoroughly laid the building of the pile is proceeded with1 the larger blocks being placed in the center to form1 as it were1 the backbone of the pile2 the smaller blocks of ore are arranged on the outside of these and in the interstices4 ,the shape or form of the pile when completed is similar to a truncated cone1 and when burning the kiln looks like a small volcano4 ,when the kiln has been filled with ore1 the whole is covered with ginesi with a view of preventing the escape of the fumes4 ,the ore is then ignited by means of bundles of straw1 impregnated or saturated with sulphur1 being held above the thin portion of the top of the kiln1 which is at once closed with ginesi1 and the calcarone is left to itself for about a week4 ,during the burning process the flames gradually descend1 and the sulphur contained in the ore is melted by the heat from above4 ,in about seven or eight days sulphuric fumes and sublimed sulphur commence to escape1 when it becomes necessary to add a new coat of ginesi to the covering and thus prevent the destruction of vegetation by the sulphur fumes4 ,the mouth of the kiln1 which has been left open in order to create a draught1 is closed up about this time with gypsum plaster4 ,when the sulphur is all liquefied it finds its way to the most depressed part of the kiln1 and there1 upon encountering the large sterile blocks1 quite cold1 already referred to1 solidifies4 ,it is again liquefied by means of burning straw1 whereupon an iron trough is inserted into a mouth made in the kiln for the purpose1 and the reliquefied sulphur runs into it1 from which it is immediately collected into wooden moulds1 called gadite1 and which have been kept cool by being submerged in water4 ,upon its becoming thoroughly cool the sulphur is taken out of the moulds referred to1 and is now in solid blocks1 each weighing about #ajj weight4 ,two of these blocks constitute a load for a mule1 and cost from #d to #e francs4 ,the above is the result when the operation succeeds2 but this is not always the case4 ,at times the sulphur becomes solidified before it reaches the mouth of the kiln1 because of the heat not being sufficient to keep it liquid in its passage thereto1 and other misfortunes not within control1 and consequent upon the use of the larger kilns1 or calcaroni4 ,when the sulphur ceases to run from the kiln1 the process is complete4 ,the residue is left to cool1 which consumes from one to two months4 ,the cooling process could be accomplished in much less time by permitting the air to enter the kiln1 but this would be destructive to vegetation1 and even to life1 consequent upon the fumes of the sulphur4 ,the greatest heat at a given time in a kiln is calculated to be above #fej degrees ,centigrade--that is1 at the close of the process4 ,this enormous heat is generally allowed to waste1 whereas it is understood it could be utilized in many ways4 ,a gentleman of the name of ,gill is understood to have invented a recuperative kiln1 which will1 if generally adopted1 utilize the heat of former processes named4 ,a ton of ore containing about #be per cent4 of sulphur yields #cjj pounds of sulphur4 ,this is considered a good yield4 ,when it yields #bjj pounds it is considered medium1 and poor when only #ge pounds4 ,laborers are paid #j4dj lire per ton for loading and unloading kilns1 and from thirty to forty hands are employed at a time4 ,the keeper of a kiln receives from #b to #b4ej lire per day4 ,notwithstanding the calcarone has many defects1 it is the simplest and cheapest mode of smelting1 and is preferred here to any other system requiring machinery and skilled labor to operate it4 ,the following are the principal furnaces in use here3 ,durand's2 ,hirzel2 ,gill and ,kayser's system of fusion2 ,conby ,bollman process2 ,thomas steam process of smelting2 and ,robert ,gill's recuperative kilns4 ,there are seven qualities or grades of sulphur1 viz43 #a4 ,sulphur almost chemically pure1 of a very bright and yellow color4 ,second ,best4--,slightly inferior to the first quality2 bright and yellow4 ,second ,good4--,contains #d to #e per cent4 of earthy matter1 but is of a bright yellow4 ,second ,current4--,dirty yellow1 containing more earthy matter than that last named4 ,third ,best4--,brownish yellow2 this tint depends on the amount of bitumen which it contains4 ,third ,good4--,light brown1 containing much extraneous matter4 ,third ,current4--,brown and coarse4 ,these qualities are decided by color1 not by test4 ,the difference of price is from #c to #aj francs per ton4 ,manufacturers prefer the third best1 because of its containing more sulphuric acid and costing less than the sulphur of better quality4 ,sulphur is conveyed to the seaboard by rail1 in carts1 or on mules or donkeys4 ,conveyance by cart1 mule1 or donkey is only resorted to when the distance is short or from mines to railroad stations4 ,the tariff in the latter case is understood to be #a lire per ton per mile4 ,the railroad tariff is #j4ab per ton per kilometer2 but it is contemplated1 it is understood1 to reduce this to #g centimes in a short time4 ,the price per ton of sulphur is as follows3 ,at ,porto ,at ,at ,grade4 ,empedocle4 ,licata4 ,catania4 ,lire4 ,lire4 ,lire4 ,second best #hf4fj #hg4jj #ij4gj ,second good #hd4db #hd4ej #ij4cj ,second current #hc4ij #hc4ij #hh4dj ,third best #gi4jj #gi4ij #hf4ij ,third good #gg4hj #gg4hj #hc4jj ,third current #gf4hj #gf4gj ,sulphur free on board1 brokerage1 shipment1 export duty1 and all other expenses included1 costs #bj lire per ton in excess of the above prices4 ,nearly all the sulphur exported from ,palermo emanates from the ,lercara mines1 in the province of ,palermo1 the price per ton being as follows3 first quality1 #ia4fj lire2 second quality1 #hh4dj4 ,sulphur is usually conveyed in steamers to foreign countries from ,sicilian ports4 ,the average freight per ton to ,new ,york is about as follows3 ,from ,palermo1 #h4gj lire2 from ,catania1 #ac4ej lire2 from ,girgenti1 #af lire4 ,an additional charge of #b4ej lire is made when the sulphur may be destined for other ports in the ,united ,states4 ,liebig once said that the degree of civilization of a nation and its wealth could be seen in its consumption of sulphuric acid4 ,now1 although ,italy produces immense quantities of sulphur1 it cannot1 on account of the scarcity of fuel1 and other obvious reasons perhaps1 compete with certain other countries in the manufacture and consumption of sulphuric acid4 ,sulphur is employed in the manufacture of sulphuric acid1 and the latter serves in the manufacture of sulphate of soda1 chloridic acid1 carbonate of soda1 azodic acid1 ether1 stearine candles1 purification of oils in connection with precious metals and electric batteries4 ,nordhausen's sulphuric acid is employed in the manufacture of indigo4 ,sulphate of soda is employed in the manufacture of artificial soda1 glassware1 cold mixtures1 and medicines4 ,carbonate of soda is used in the manufacture of soap1 bleaching wool1 coloring and painting tissues1 and in the manufacture of fine crystal ware and the preparation of borax4 ,chloric acid is used in the preparation of chlorides with bioxide of manganese1 and with chlorides in the preparation of hypochlorides of lime1 known in commerce under the name of bleaching powder1 and improperly called chloride of lime1 which is used as a disinfectant in contagious diseases1 in bleaching stuffs1 and in the manufacture of paper from vegetable fibers1 and in the manufacture of gelatine extracted from bones1 as well as in fermenting molasses and in the manufacture of sugar from beet root4 ,sulphur is also used in the preparation of gunpowder and oil of vitriol1 and in the manufacture of matches and cultivation of the vine4 ,in the year #ahch the ,neapolitan government granted a monopoly to a ,french company for the trade in sulphur4 ,by the terms of the agreement the producers were required to sell their sulphur to the company at certain fixed prices1 and the latter paid the government the sum of #cej1jjj annually in consideration of this requirement4 ,this1 however1 was not a success1 and tended to curtail the sulphur industry1 and the government1 discovering the agreement to be against its interests1 annulled it1 and established a free system of production1 charging an export tax per ton only4 ,at that time sulphuric acid was derived exclusively from sulphur4 ,hence the demand from all countries was great1 and the prices paid for sulphur were high4 ,it was about this period that the sulphur industry was at its zenith4 ,the monopoly having been abolished1 every mine did its utmost to produce as much sulphur as possible1 and from the export duty exacted by the government there accrued to it a much larger revenue than that which it received during the period of the monopoly4 ,the progress of science has1 however1 modified the state of things since then1 as sulphur can now be obtained from pyrite or pyrite of iron4 ,this discovery immediately caused the price of sulphur to fall1 and the great demand therefore correspondingly ceased4 ,in ,england1 at the present time1 it is understood that two-thirds of the sulphuric acid used is manufactured from pyrites4 ,the decrease in prices caused many of the mines to suspend operations1 and as a result the sulphur remained idle in stock4 ,in #ahhd an association was formed at ,catania with a view to buying up sulphur thus stored away at the mines and various ports at low prices1 and store it away until a favorable opportunity should present itself for the sale thereof4 ,this had the effect of increasing the prices of sulphur in ,sicily for some time1 and the producers1 discovering that the methods of the association increased the foreign demand for their produce as well as its prices1 exported it directly themselves1 thus breaking up the association referred to1 as it was no longer a profitable concern4 ,the railroad system1 which in later years has placed the most important parts of ,sicily in communication with the seaboard1 has been most beneficial to the sulphur industry4 ,a great saving has been made in transporting it to the ports4 ,this was formerly 7as stated7 accomplished by carts drawn by mules at an enormous expense1 as the roads were wretched1 and unless some person of distinction contemplated passing over them1 repairs were unknown4 ,palermo1 ,march #bj1 #ahhh4 99 99 99 99 99 ,,an ,,automatic ,,still4 ,,by ,t4 ,,maben4 ,the arrangement here described is one that may readily be adapted to1 and is specially suited for1 the old fashioned stills which are in frequent use among pharmacists for the purpose of distilling water4 ,the idea is extremely simple1 but ,i can testify to its thorough efficiency in actual practice4 ,the still is of tinned copper1 two gallon capacity1 and the condenser is the usual worm surrounded with cold water4 ,the overflow of warm water from the condenser is not run into the waste pipe as in the ordinary course1 but carried by means of a bent tube1 ,a1 ,b1 ,c1 to the supply pipe of the still4 ,the bend at ,b acts as a trap1 which prevents the escape of steam4 ,illustration ,the advantages of this arrangement are obvious4 ,it is perfectly simple1 and can be adapted at no expense4 ,it permits of a continuous supply of hot water to the still1 so that the contents of the latter may always be kept boiling rapidly1 and as a consequence it condenses the maximum amount of water with the minimum of loss of heat4 ,if the supply of water at ,d be carefully regulated1 it will be found that a continuous current will be passing into the still at a temperature of about #ahj ,f41 or1 if practice suggest the desirability of running in the water at intervals1 this can be easily arranged4 ,it is necessary that the level at ,a should be two inches or thereabout higher than the level of the bend at ,c1 otherwise there may not be sufficient head to force a free current of water against the pressure of steam4 ,it will also be found that the still should only contain water to the extent of about one-fourth of its capacity when distillation is commenced1 as the water in the condenser becomes heated much more rapidly than the same volume is vaporized4 ,by this expedient a still of two gallons capacity will yield about half a dozen gallons per day1 a much greater quantity than could ever be obtained under the old system1 which required the still to be recharged with cold water every time one and a half gallons had been taken off4 ,the objection to all such continuous or automatic arrangements is1 of course1 that the condensed water contains all the free ammonia that may have existed in the water originally1 but it is only in cases where the water is exceptionally impure that this disadvantage will become really serious4 ,the method here outlined has1 no doubt1 occurred to many1 and may probably be in regular use1 but not having seen any previous mention of the idea1 ,i have thought that it might be useful to some pharmacists who prepare their own distilled water4--,phar4 ,jour4 99 99 99 99 99 ,,cotton ,,seed ,,oil4 ,cotton seed oil1 said ,mr4 ,a4,e4 ,thornton1 of the ,atlanta mills1 is one of the most valuable of oils because it is a neutral oil1 that is1 neither acid nor alkali1 and can be made to form the body of any other oil4 ,it assimilates the properties of the oil with which it is mixed4 ,for instance1 olive oil4 ,cotton seed oil is taken and a little extract of olives put in4 ,the cotton oil takes up the properties of the extract1 and for all practical purposes it is every bit as good as the pure olive oil4 ,then it is used in sweet oil1 hair oil1 and1 in fact1 in nearly all others4 ,a chemist cannot tell the prepared cotton oil from olive oil except by exposing a saucerful of each1 and the olive oil becomes rancid much quicker than the cotton oil4 ,the crude oil is worth thirty cents a gallon1 and even as it is makes the finest of cooking lard1 and enters into the composition of nearly all lard4 ,a visit to the mills showed how the oil is made4 ,from the platform where the seed is unloaded it is thrown into an elevator and carried by a conveyor--an endless screw in a trough--to the warehouse4 ,then it is distributed by the conveyor uniformly over the length of the building--about #bjj feet4 ,the warehouse is nearly half filled now1 and thousands and thousands of bushels are lying in store4 ,another elevator carries the seed up to the sand screen4 ,this is a revolving cylinder made of wire cloth1 the meshes being small enough to retain the seed1 which are inside the cylinder1 but the sand and dirt escape4 ,now the seeds start down an inclined trough4 ,there is something else to be taken out1 and that is the screws and nails and rocks that were too large to be sifted out with the sand and dirt4 ,there is a hole in the inclined trough1 and up through that hole is blown a current of air by a suction fan4 ,if it were not for the fan1 the cotton seed1 rocks1 nails1 and all would fall through4 ,the current keeps up the cotton seed1 and they go on over1 but it is not strong enough to keep up the nails and pebbles1 and they fall through4 ,now the seed1 free of all else1 is carried by another elevator and endless screw conveyor to the linter4 ,this is really nothing more than a cotton gin with an automatic feed4 ,,huller ,,and ,,heaters4 ,then the seed is carried to the huller1 where it is crushed or ground into a rough meal about as coarse as the ordinary corn grits4 ,the next step is to separate the hulls from the kernels1 all the oil being in the kernel1 so the crushed seed is carried to the separator4 ,this is very much on the style of a sand screen1 being a revolving cylinder of wire cloth4 ,the kernels1 being smaller than the broken hulls1 fall through the broken meshes1 and upon this principle the hull is separated and carried direct to the furnace to be used as fuel4 ,the kernels are ground as fine as meal1 very much as grist is ground1 between corrugated steel rollers1 and the damp1 reddish colored meal is carried to the heater4 ,the heater is one iron kettle within another1 the six inch steam space between the kettles being connected direct with the boilers4 ,there are four of these kettles side by side4 ,the meal is brought into this room by an elevator1 the first heater is filled1 and for twenty minutes the meal is subjected to a dry cook1 a steam cook1 the steam in the packet being under a pressure of forty-five pounds4 ,inside the inner kettle is a stirrer1 a revolving arm attached at right angles to a vertical shaft4 ,the stirrer makes the heating uniform1 and the high temperature drives off all the water in the meal1 while the involatile oil all remains4 ,in five minutes the next heater is filled1 in five minutes the next1 etc4 ,now there are four heaters1 and as the last heater is filled--at the end of twenty minutes--the first heater is emptied4 ,then at the end of five minutes the first heater is filled1 and the one next to it is emptied1 and the rotation is kept up1 each heater full of meal being dry-cooked for twenty minutes4 ,corresponding to the four heaters are four presses4 ,each press consists of six iron pans1 shaped like baking pans1 arranged one above the other1 and about five inches apart4 ,the pans are shallow1 and around the edge of each is a semicircular trough1 and at the lowest point of the trough is a funnel-shaped hole to enable the oil to run from one pan to the next lowest1 and from the lowest pan to the receiving tanks below4 ,,pressing ,,out ,,the ,,oil4 ,as soon as a heater is ready to be emptied1 the meal is taken out and put into six hair sacks1 corresponding to the six pans in the press4 ,there are six hair mats about one foot wide and six long1 one side of each being coated with leather4 ,the hair mat is about an inch thick4 ,now the hair sack1 containing ten and a half to eleven pounds of heated steaming meal1 is placed on one end of the mat1 and the meal distributed so as to make a pad or cushion of uniform thickness4 ,the pad of meal is not quite three feet long1 a foot wide1 and three inches thick1 and the hair mat is folded over1 sandwiching the pad and leaving the leather coating of the pad outside4 ,in this form the six loads are put into the six pans1 and by means of a powerful hydraulic press the pans are slowly pressed together4 ,the oil begins trickling out at the side1 slowly at first1 and then suddenly it begins running freely4 ,the pressure on the loads is #cej tons4 ,after being pressed about five minutes1 the pressure is eased off and the loads taken out4 ,what had been a mushy pad three inches thick is a hard1 compact cake about three-quarters of an inch thick1 and the sack is literally glued to the cake4 ,the crude oil has a reddish muddy color as it runs into the tanks4 ,to one side were lying great heaps of sacks of yellowish meal--the cakes which have been broken and ground up into meal4 ,that1 as explained above1 forms the body of all fertilizers4 ,the following is a summary of the work for the eight months' season at the ,atlanta mills3 ,fifteen thousand tons of seed used give3 ,fifteen million pounds of hull4 ,ten million three hundred and thirty-one thousand two hundred and fifty pounds of meal4 ,four million six hundred and sixty-eight thousand seven hundred and fifty pounds of oil4 ,three hundred thousand pounds of lint cotton4 ,the meal is worth at the rate of #f for #gjj pounds1 or #hh1fjc4eh4 ,the oil is worth thirty cents a gallon1 or seven and a half pounds1 or #ahf1gej4 ,the lint is worth #ah1jjj1 making a total of #bic1cec1 and that doesn't include the #ae1jjj1jjj pounds of hull4--,atlanta ,constitution4 99 99 99 99 99 ,,manufacture ,,of ,,photographic ,,sensitive ,,plates4 ,quite recently ,messrs4 ,marion ,company1 ,london1 began on their own account to manufacture sensitive photographic plates by machinery1 and the operations are exceedingly delicate1 for a single minute air bubble or speck of dust on a plate may mar the perfection of a picture4 ,their works for the purpose at ,southgate were erected in the summer of #ahhf1 and were designed throughout by ,mr4 ,alexander ,cowan4 ,illustration3 ,fig4 #a4 ,buildings of this kind have to be specially constructed1 because some of the operations have to be carried on in the absence of daylight1 and in that kind of non-actinic illumination which does not act upon the particular description of sensitive photographic compound manipulated4 ,glass and other materials have therefore to pass from light to dark rooms through double doors or double sliding cupboards made for the purpose1 and the workshops have to be so placed in relation to each other that the amount of lifting and the distance of carriage of material shall be reduced to a minimum4 ,moreover1 the final drying of sensitive photographic plates takes place in absolute darkness4 ,fig4 #a is a ground plan of the chief portion of the works4 ,in this cut1 ,a is the manager's private office1 ,b the counting house1 ,c the manager's laboratory1 and ,d his dark room for private experiment1 which can thus be conducted without interfering with the regular work of the establishment4 ,e is the carpenter's shop and packing room1 ,f the albumen preparation room1 ,g the engine room1 with its two doors2 the position of the engine is marked at ,h4 ,the main building is entered through the door1 ,k2 the passage1 ,l1 is used for the storage of glass1 and has openings in the wall on one side to permit the passage of glass into the cleaning room1 ,m2 this room is illuminated by daylight4 ,the plates1 after being cleaned1 pass into the coating rooms1 ,n and ,o1 into which daylight is never admitted2 the coating machine is in the room1 ,n1 and three hand coating tables in the room1 ,o2 both these rooms are illuminated by non-actinic light4 ,illustration3 ,fig4 #b4 ,illustration3 ,fig4 #c4 ,the walls of ,n and ,o are of brick1 to keep these interior rooms as cool as possible in hot weather1 for the making of photographic plates is more difficult in summer time1 because the high temperature tends to prevent the rapid setting of the gelatine emulsion upon them4 ,at the end of these rooms and communicating with both is the lift1 ,p1 by which the coated plates are carried to the drying rooms above1 which there cover the entire area of the main building2 they consist of two rooms measuring #fj ft4 by #cj ft41 and are each #cj ft4 high at the highest part in the center of the building2 these rooms are necessarily kept in absolute darkness1 except while the plates are being stored therein or removed therefrom1 and on such occasions non-actinic light is used4 ,after the plates are dry1 they come down the lift1 ,q1 into the cutting and packing room1 ,r1 which is illuminated by non-actinic light4 ,in the drying rooms the batches of plates are placed one after the other on tram lines at one end of the room1 and are gradually pushed to the other end of the building1 so that the first batches coated are the first to be ready to be taken off when dry1 and to be sent down the lift1 ,q4 ,the plates in ,r1 when sufficiently packed to be safe from the action of daylight1 are passed through specially constructed openings into the outside packing room1 ,s1 where they are labeled4 ,the chemicals are kept in the room1 ,u1 where they are weighed and measured ready for the making of the photographic emulsion in the room1 ,u4 ,the next room1 ,v1 is for washing small experimental batches of emulsion1 and ,w is the large washing room4 ,the emulsion is then taken into the passage1 ,x1 communicating with the two coating rooms4 ,a centrifugal machine in the room1 ,y1 is used for extracting silver residues from waste materials1 also for freeing the emulsion from all soluble salts4 ,washing and cleaning in general go on in the room1 ,z4 ,illustration3 ,fig4 #d4 ,the glass for machine coating is cut to standard sizes at the starting1 instead of being coated in large sheets and cut afterward--a practice somewhat common in this industry4 ,the disadvantage of the ordinary plan is that minute fragments of glass are liable to settle upon the sensitive film and to cause spots and scratches during the packing operations2 any defect of this kind renders a plate worthless to the photographer4 ,when any breakages take place in the cutting1 it is best that they should occur at the outset1 and not after the plate has been coated with emulsion4 ,the cutting when necessary is effected by the aid of a cutting board1 ,fig4 #b1 invented by ,mr4 ,cowan1 and now largely in use in the photographic world4 ,this appliance is used to divide into two equal parts1 with absolute exactness1 any plate within its capacity1 and it is especially useful in dimly lighted rooms4 ,it consists of four rods pivoted together at the corners and swinging on two centers1 so that in the first position it is truly square1 and in other positions of rhomboid form1 the two outer bars approaching each other like those of a parallel ruler4 ,the hinge flap comes down on the exact center of the plate1 minus the thickness of the block holding the diamond4 ,by this appliance plates can be cut in either direction4 ,fig4 #c represents a similar arrangement for cutting a number of very small plates out of one large one2 in this the hinge flap is made in the form of a gridiron1 and the bars are spaced at accurate distances1 according to the size of the plate to be cut1 so that a plate #aj in4 square1 receiving four cuts in each direction1 will be divided into twenty-five small plates4 ,illustration3 ,fig4 #e4 ,before being cleaned all sharp edges are roughly taken off those plates intended for machine coating by girls1 who rub the edges and corners of the plates upon a stone2 the plates are then cleaned by any suitable method in use among photographers4 ,the plates1 now ready for the coating room1 have to be warmed to the temperature of the emulsion1 say from #hj deg4 ,f4 to #ajj deg4 ,f41 before they pass to the coating machine1 the inventor of which1 ,mr4 ,cadett1 having come to the conclusion that1 if the plates are not of the proper temperature1 the coating given will be uneven over various parts of the surface4 ,the plate-warming machine is represented in ,fig4 #d2 it was designed by ,mr4 ,a4 ,cowan1 and made by his son1 ,mr4 ,a4 ,r4 ,cowan4 ,it consists of a trough #g ft4 long by #c in4 deep1 forming a flat tank1 through which hot water passes by means of the circulating system shown in the engraving4 ,to facilitate the traveling of the glass plates without friction the top of the tank is a sheet of plate glass bedded on a sand bath4 ,an assistant at one end places the glasses one after the other on the warm glass slab1 and by means of a movable slide pushes them one at a time under the cover1 which cover is represented raised in the engraving to show the interior of the machine4 ,after having put one glass plate on the slide1 another cannot be added until the man in the dark room at the other end of the slide has taken off the farthest warmed plate1 because the slide has a reciprocating movement4 ,this heating apparatus is built at right angles to the coating machine in the next room1 in order to be conveniently placed in the present building2 but it is intended in future to use it as a part of the coating machine itself1 and to drive it at the same speed and with the same gearing1 so that the cold plates will be put on by hand at one end1 get warmed as they pass into the dark room1 at the other end of which they will be delivered by the machine in coated condition4 ,underneath the heating table is a copper boiler1 with its ,bunsen's burner of three concentric rings to get up the temperature quickly and to give the power of keeping the water under the heating slab at a definite temperature1 as indicated by a thermometer4 ,the cold water tank of the system is represented against the wall in the cut4 ,illustration3 ,fig4 #f4 ,fig4 #e represents the hot water circulating system outside the coating rooms for keeping the gelatine emulsions in these dimly lighted regions at a given temperature1 without liberating the products of combustion where the emulsion is manipulated4 ,the temperature is regulated automatically4 ,it will be noticed where the pipes enter the two coating rooms1 and ,fig4 #f shows the copper inside one of them heated by the apparatus just described4 ,the emulsion vessel in the copper is surrounded by warm water1 and the copper itself is jacketed and connected with the hot water pipes1 so forming part of the circulating system4 ,illustration3 ,fig4 #g4 ,fig4 #g is a general view of the coating machine recently invented by ,mr4 ,cadett1 of the ,greville ,works1 ,ashtead1 ,surrey4 ,the plates warmed in the light room1 as already described1 are delivered near the end of the coating table1 where they are picked off a gridiron-like platform1 represented on the right hand side of the cut1 and are placed by an assistant one by one upon the parallel gauges shown at the beginning of the machine proper2 they are then carried on endless cords under the coating trough described farther on4 ,after they have been coated they are carried onward upon a series of four broad endless bands of absorbent cotton--,turkish toweling answers well--and this cotton is kept constantly soaked with cold water1 which flows over sheets of accurately leveled plate glass below and in contact with the toweling2 the backs of the plates being thus kept in contact with fresh cold water1 the emulsion upon them is soon cooled down and is firmly set by the time the plates have reached the end of the series of four wet tables4 ,they are then received upon one over which dry toweling travels1 which absorbs most of the moisture which may be clinging to the backs of the plates2 very little wet comes off the backs1 so that during a day's work it is not necessary to adopt special means to redry this last endless band4 ,what are technically known as whole plates1 which are #h in4 by #f in41 are placed touching each other end to end as they enter the machine1 and they travel through it at the rate of #gbj per hour2 smaller sizes are coated in proportion1 the smaller the plates the larger is the number coated in a given time4 ,the smaller plates pass through the machine in two parallel rows1 instead of in a single row1 so that quarter plates1 #d in4 by #c in41 are delivered at the end of the machine at the rate of #b1hjj per hour1 keeping two attendants well employed in picking them up and placing them in racks as quickly as they can do the work4 ,the double row of cords for carrying two lines of small plates through the machine is represented in the engraving4 ,although the plates touch each other at their edges on entering the machine1 they are separated from each other by short intervals after being coated2 this is effected by differential gearing4 ,the water flowing over the tables for cooling the plates is caught in receptacles below and carried away by pipes4 ,between each of the tables is a little roller to enable small plates to travel without tilting over the necessary gap between each pair of bands4 ,illustration3 ,fig4 #h4 ,the feeding trough of ,cadett's machine is represented in ,fig4 #h4 ,the plates1 cleaned as already described1 are carried upon the cords under a brass roller1 the weight of which causes sufficient friction to keep the plates from tilting2 they next pass under a soft camel's hair brush to remove anything in the shape of dust or grit1 and are then coated4 ,they afterward pass over a series of accurately leveled wheels running in a tank of water kept exact by an automatic regulator at a temperature of from #hj deg4 ,fah4 to #ajj deg4 ,fah41 by means of a small hot water circulating system4 ,the emulsion trough is jacketed with hot water at a constant temperature4 ,this trough is silver plated inside1 because most metals in common use would spoil the emulsion by chemical action4 ,the trough is #af in4 long2 it somewhat tapers toward the bottom1 and contains a series of silver pumps shown in the cut2 the whole of this series of pumps is connected with one long adjustable crank when plates of the largest size have to be coated2 when coating plates of smaller sizes some of the pumps are detached4 ,a chief object of the machine is to deliver a carefully measured quantity of emulsion upon each plate1 and this is done by means of pumps1 in order that the quantity of emulsion delivered shall not be affected by changes in the level of the emulsion in the trough2 the quantity delivered is thus independent of variations due to gravity or to the speed of the machine4 ,these pumps draw the emulsion from a sufficient depth in the trough to avoid danger from the presence of air bubbles1 and the bottom of the trough is so shaped that should by chance any sedimentary matter be present1 it has a tendency to travel downward1 away from the bottoms of the pumps4 ,there is a steady flow of emulsion from the pumps to the delivery pipes1 then it passes down a guide plate of the exact width of the plate to be coated4 ,immediately in front of the guide plate is a fixed silver cylinder1 kept out of contact with the plate by the thickness of a piece of fine and very hard hempen cord1 which can be renewed from time to time4 ,these cords keep the cylinder from scraping the emulsion off the plate1 and they help to distribute it in an even layer4 ,there would be two lines upon each plate where it is touched by the cords1 were not the emulsion so fluid as to flow over the cut-like lines made and close them up4 ,illustration3 ,fig4 #i4 ,the silver cylinder to a certain extent overcomes the effects of irregularities in the glass plates1 for the cylinder is jointed somewhat in the cup and ball fashion1 and is made in two or more parts1 which parts are held together by lengths of ,india rubber4 ,the arrangement is shown in section in ,fig4 #i1 in which ,a is the hot water jacket of the emulsion vessel2 ,b1 the crank driving the pumps2 ,c1 a pump with piston in position2 ,d1 delivery tube of the pump2 ,e1 the silver guide plate to conduct the emulsion down to the glass2 ,f1 the spreading cylinder2 ,g1 the cords regulating the distance of the cylinder from the glass plates2 ,h1 soft camel's hair brush2 ,k1 friction roller2 ,l ,l ,l1 three plates passing under the emulsion tank2 ,m1 knife edged wheels in the hot water tank1 ,n2 the plucking roller1 ,p1 has a hot water tank of its own1 and travels at slightly greater speed than the other rollers2 ,r is the beginning of the cooling bands2 ,t1 the driving cords2 and ,w1 a level of the emulsion in the trough4 ,y represents one of the bucket pistons of the pumps1 detached4 ,the construction of the crank itself is such that1 by adjustment of the connecting rods1 more or less emulsion may be put upon the plates4 ,mr4 ,cowan1 however1 intends to adjust the pumps once for all1 and to regulate the amount of emulsion delivered upon the plates by means of driving wheels of different diameters upon the cranks4 ,illustration3 ,fig4 #aj4 ,fig4 #aj is a section of the hollow spreading cylinder1 made of sheet silver as thin as paper1 so that its weight is light4 ,for coating large plates it is divided in the center1 so as to adapt itself somewhat to irregularities in the surface of each plate4 ,in this case it is supported by a third and central thread1 as represented in the cut4 ,otherwise the cylinder would touch the center of the plate4 ,its two halves are held together by a slip of ,india rubber4--,the ,engineer4 99 99 99 99 99 ,,the ,,use ,,of ,,ammonia ,,as ,a ,,refrigerating ,,agent4#a ,footnote #a3 ,paper lately read before the ,civil and ,mechanical ,engineers' ,society4 ,,by ,,mr4 ,t4,b4 ,,lightfoot1 ,m4,i4,c4,e4 ,within the last few years considerable progress has been made in the application of refrigerating processes to industrial purposes1 and the demand for refrigerating apparatus thus created has led to the production of machines employing various substances as the refrigerating agent4 ,in a paper read by the author before the ,institution of ,mechanical ,engineers1 in ,may1 #ahhf1 these systems were shortly described1 and general comparisons given as to their respective merits1 scope of application1 and cost of working4 ,in the present paper it is proposed to deal entirely with the use of ammonia as a refrigerating agent1 and to deal with it in a more full and comprehensive manner than was possible in a paper devoted to the consideration of a number of different systems and apparatus4 ,in the ,united ,states and in ,germany1 as well as to some extent elsewhere1 ammonia has been very generally employed for refrigerating purposes during the last ten years or so4 ,in this country1 however1 its application has been extremely limited2 and even at the present time there are but few ammonia machines successfully at work in ,great ,britain4 ,no doubt this is1 to a large extent1 due to the fact that in the ,united ,states and in ,germany there existed certain stimulating causes1 both as regards climate and manufactures1 while in this country1 on the other hand1 these causes were present only in a modified degree1 or were absent altogether4 ,the consequence was that up to a comparatively recent date the only machine manufactured on anything like a commercial scale was the original ,harrison's ether machine1 first produced by ,siebe1 about the year #aheg--;a machine which1 though answering its purpose as a refrigerator1 was both costly to make and costly to work4 ,in #ahgh the desirability of supplementing our then existing meat supply by means of the large stocks in our colonies and abroad led to the rapid development of the special class of refrigerating apparatus commonly known as the dry air refrigerator1 which1 in the first instance1 was specially designed for use on board ship1 where it was considered undesirable to employ chemical refrigerants4 ,owing to their simplicity1 and perhaps also to their novelty1 these cold air machines have very frequently been applied on land1 under circumstances in which the same result could have been obtained with much greater economy by the use of ammonia or some other chemical agent4 ,recently1 however1 more attention has been directed to the question of economy1 and consideration is now being given to the applicability of certain machines to certain special purposes1 with the result that ammonia--which is the agent that1 in our present state of knowledge1 gives as a rule the best results for large installations1 while on land at any rate its application for all refrigerating purposes presents no unusual difficulties--promises to become largely adopted4 ,it is hoped1 therefore1 that the following paper respecting its use will be of interest4 ,in all cases where a liquid is employed1 the refrigerating action is produced by the change in physical state from the liquid to the vaporous form4 ,it is1 of course1 well known that such a change can only be brought about by the acquirement of heat2 and for the purpose of refrigeration 7by which must be understood the abstraction of heat at temperatures below the normal7 it is obvious that1 other things being equal1 that liquid is the best which has the highest heat of vaporization1 because with it the least quantity has to be dealt with in order to produce a given result4 ,in fact1 however1 liquids vary1 not only in the amount of heat required to vaporize them 7this amount also varying according to the temperature or pressure at which vaporization occurs71 but also in the conditions under which such change can be effected4 ,for instance1 water has an extremely high latent heat1 but as its boiling point at atmospheric pressure is also high1 evaporation at such temperatures as would enable it to be used for refrigerating purposes can only be effected under an almost perfect vacuum4 ,the boiling point of anhydrous ammonia1 on the other hand1 is #cg below zero ,f4 at atmospheric pressure1 and therefore for all ordinary cooling purposes its evaporation can take place at pressures considerably above that of our atmosphere4 ,some other agents used for refrigerating purposes are methylic ether1 ,pictet's liquid1 sulphur dioxide1 and ether4 ,in this connection it should be stated that ,pictet's liquid is a compound of carbon dioxide and sulphur dioxide1 and is said to possess the property of having vapor tensions not only much below those of pure carbon dioxide at equal temperatures1 but even below those of pure sulphur dioxide at temperatures above #gh ,f4 ,the considerations1 therefore1 which chiefly influence the selection of a liquid refrigerating agent are3 #a4 ,the amount of heat required to effect the change from the liquid to the vaporous state1 commonly called the latent heat of vaporization4 #b4 ,the temperatures and pressures at which such change can be effected4 ,this latter attribute is of twofold importance2 for1 in order to avoid the renewal of the agent1 it is necessary to deprive it of the heat acquired during vaporization1 under such conditions as will cause it to assume the liquid form1 and thus become again available for refrigeration4 ,as this rejection of heat can only take place if the temperature of the vapor is somewhat above that of the cooling body which receives the heat1 and which1 for obvious reasons1 is in all cases water1 the liquefying pressure at the temperature of the cooling water1 and the facility with which this pressure can be reached and maintained1 is of great importance in the practical working of any refrigerating apparatus4 ,ammonia in its anhydrous form1 the use of which is specially dealt with in this paper1 is a liquid having at atmospheric pressure a latent heat of vaporization of #ijj1 and a boiling point at the same pressure of #cg below zero ,f4 ,water being unity1 the specific gravity of the liquid at a temperature of #dj ,f4 is #j4gf1 and the specific gravity of its vapor is #j4ei1 air being unity4 ,in the use of ammonia1 two distinct systems are employed4 ,so far1 however1 as the mere evaporating or refrigerating part of the process is concerned1 it is the same in both4 ,the object is to evaporate the liquid anhydrous ammonia at such tension and in such quantity as will produce the required cooling effect4 ,the actual tension under which this evaporation should be effected in any particular case depends entirely upon the temperature at which the acquirement of heat is to take place1 or1 in other words1 on the temperature of the material to be cooled4 ,the higher the temperature1 the higher may be the evaporating pressure1 and therefore the higher is the density of the vapor1 the greater the weight of liquid evaporated in a given time1 and the greater the amount of heat abstracted4 ,on the other hand1 it must be remembered that1 as in the case of water1 the lower the temperature of the evaporating liquid1 the higher is the heat of vaporization4 ,it is in the method of securing the rejection of heat during condensation of the vapor that the two systems diverge1 and it will be convenient to consider each of these separately4 ,the ,absorption ,process4--,the principle employed in this process is physical rather than mechanical4 ,ordinary ammonia liquor of commerce of #j4hhj specific gravity1 which contains about #ch per cent4 by weight of pure ammonia and #fb per cent4 of water1 is introduced into a vessel named the generator4 ,this vessel is heated by means of steam circulating through coils of iron piping1 and a mixed vapor of ammonia and water is driven off4 ,this mixed vapor is then passed into a second vessel1 in order to be subjected to the cooling action of water4 ,and here1 owing to the difference between the boiling points of water and ammonia1 fractional condensation takes place1 the bulk of the water1 which condenses first1 being caught and run back to the generator1 while the ammonia in a nearly anhydrous state is condensed and collected in the lower part of the vessel4 ,this process of fractional condensation is due to ,rees ,reece1 and forms an important feature in the modern absorption machine4 ,prior to the introduction of this invention1 the water evaporated in the generator was condensed with the ammonia1 and interfered very seriously with the efficiency of the process by reducing the power of the refrigerating agent by raising its boiling point4 ,in the improved form of apparatus1 ammonia is obtained in a nearly anhydrous condition1 and in this state passes on to the refrigerator4 ,in this vessel1 which is in communication with another vessel called the absorber1 containing cold water or very weak ammonia liquor1 evaporation takes place1 owing to the readiness with which cold water or weak liquor absorbs the ammonia1 water at #ei ,fahr4 absorbing #gbg times its volume of ammonia vapor4 ,the heat necessary to effect this vaporization is abstracted from brine or other liquid1 which is circulated through the refrigerator by means of a pump4 ,owing to the absorption of ammonia1 the weak liquor in the absorber becomes strengthened1 and it is then pumped back into the generating vessel to be again dealt with as above described4 ,the absorption apparatus1 as applied for cooling purposes1 consists of a generator1 which is a vessel of cast iron containing coils of iron piping to which steam at any convenient pressure is supplied2 an analyzer1 in which a portion of the water vapor is condensed1 and from which it flows back immediately into the generator2 a rectifier and condenser1 in the upper portion of which a further condensation of water vapor and a little ammonia takes place1 the liquid thus formed passing back by a pipe to the analyzer and thence to the generator1 while in the lower portion the ammonia vapor is condensed and collected2 and a refrigerator or cooler1 into which the nearly anhydrous liquid obtained in the condenser is admitted by a pipe and regulating valve1 and allowed to evaporate1 the upper portion being in communication with the absorber4 ,through this vessel weak liquor1 which has been deprived of its ammonia in the generator1 is continually circulated1 after being first cooled in an economizer by an opposite current of strong cold liquor passing from the absorber to the generator1 while1 in addition1 the liquor in the absorber1 which would become heated by the liberation of heat due to the absorption and consequent liquefaction of the ammonia vapor1 is still further cooled by the circulation of cold water4 ,as the pressure in the absorber is much lower than that in the generator1 the strong liquor has to be pumped into the latter vessel1 and for this purpose pumps are provided4 ,though of necessity the various operations have been described separately1 the process is a continuous one1 strong liquor from the absorber being constantly pumped into the generator through the heater or economizer1 while nearly anhydrous liquid ammonia is being continually formed in the condenser1 then evaporated in the refrigerator and absorbed by the cool weak liquor passing through the absorber4 ,putting aside the effect of losses from radiation1 etc41 all the heat expended in the generator will be taken up by the water passing through the condenser1 less that portion due to the condensation of the water vapor in the analyzer1 and plus the amount due to the difference between the temperature of the liquid as it enters the generator and the temperature at which it leaves the condenser4 ,in the refrigerator the liquid ammonia1 in becoming vaporized1 will take up the precise quantity of heat that was given off during its cooling and liquefaction in the condenser1 plus the amount due to the difference in heat of vaporization1 owing to the lower pressure at which the change of state takes place in the refrigerator1 and less the small amount due to the difference in temperature between the vapor entering the condenser and that leaving the refrigerator1 less also the amount necessary to cool the liquid ammonia to the refrigerator temperature4 ,when the vapor enters into solution with the weak liquor in the absorber1 the heat taken up in the refrigerator is imparted to the cooling water1 subject also to corrections for differences of pressure and temperature4 ,the sources of loss in such an apparatus are3 a4 ,radiation and conduction of heat from all vessels and pipes above normal temperature1 which can1 to a large extent1 be prevented by lagging4 b4 ,conduction of heat from without into all vessels and pipes that are below normal temperature1 which can also to a large extent be prevented by lagging4 c4 ,inefficiency of economizer1 by reason of which heat obtained by the expenditure of steam in the generator is passed on to the absorber and there uselessly imparted to the cooling water4 d4 ,the entrance of water into the refrigerator1 due to the liquid being not perfectly anhydrous4 e4 ,the useless evaporation of water in the generator4 ,with regard to the amount of heat used1 it will have been seen that the whole of that required to vaporize the ammonia1 and whatever water vapor passes off from the generator1 has to be supplied from without4 ,owing to the fact that the heating takes place by means of coils1 the steam passed through may be condensed1 and thus each pound can be made to give up some #iej units of heat4 ,with the absorption process worked by an efficient boiler1 it may be taken that #bjj1jjj thermal units per hour may be eliminated by the consumption of about #ajj lb4 of coal per hour1 with a brine temperature in the refrigerator of about #bj ,fahr4 ,compression ,process4--,in this process ammonia is used in its anhydrous form4 ,so far as the action of the refrigerator is concerned1 it is precisely the same as it is in the case of the absorption apparatus1 but instead of the vapor being liquefied by absorption by water1 it is drawn from the refrigerator by a pump1 by means of which it is compressed and delivered into the condenser at such pressure as to cause its liquefaction at the temperature of the cooling water4 ,it must be borne in mind1 however1 that allowance must be made for the rise of temperature of the water passing through the condenser1 and also for the difference in temperature necessary in order to permit the transfer of heat from one side of the cooling surface to the other4 ,in a compression machine the work applied to the pump may be accounted for as follows3 a4 ,friction4 b4 ,heat rejected during compression and discharge4 c4 ,heat acquired by the ammonia in passing through the pump4 d4 ,work expended in discharging the compressed vapor from the pump4 ,but against this must be set the useful mechanical work performed by the vapor entering the pump4 ,the heat rejected in the condenser is the heat of vaporization taken up in the refrigerator1 less the amount due to the higher pressure at which the change in physical state occurs1 plus the heat acquired in the pump1 and less the amount due to the difference between the temperature at which the vapor is liquefied in the condenser and that at which it entered the pump4 ,an ammonia compression machine1 as applied to ice making1 contains ice-making tanks1 in which is circulated a brine mixture1 uncongealable at any temperature likely to be reached during the process4 ,this brine also circulates around coils of wrought iron pipes1 in which the liquid ammonia passing from the condenser is vaporized1 the heat required for this vaporization being obtained from the brine4 ,a pump draws off the ammonia vapor from the refrigerator coils1 and compresses it into the condenser1 where1 by means of the combined action of pressure and cooling by water1 it assumes a liquid form1 and is ready to be again passed on to the refrigerator for evaporation4 ,the ammonia compression process is more economical than the absorption process1 and with a good boiler and engine about #bdj1jjj thermal units per hour can be eliminated by the expenditure of #ajj lb4 of coal per hour1 with a brine temperature in the refrigerator of about #bj ,fahr4 ,,general ,,considerations4 ,from what has been said1 it will have been seen that1 so far as the mere application is concerned1 there is no difference whatever between the absorption and compression processes4 ,the following considerations1 therefore1 which chiefly relate to the application of refrigerating apparatus1 will be dealt with quite independent of either system4 ,the application of refrigerating apparatus may roughly be divided into the following heads3 a4 ,ice making4 b4 ,the cooling of liquids4 c4 ,the cooling of stores and rooms4 ,ice ,making4--,for this purpose two methods are employed1 known as the can and cell systems respectively4 ,in the former1 moulds of tinned sheet copper or galvanized steel of the desired size are filled with the water to be frozen1 and suspended in a tank through which brine cooled to a low temperature in the refrigerator is circulated4 ,as soon as the water is completely frozen1 the moulds are removed1 and dipped for a long time into warm water1 which loosens the blocks of ice and enables them to be turned out4 ,the thickness of the blocks exercises an important influence upon the number of moulds required for a given output1 as a block #i in4 thick will take four or five times as long to freeze solid as one of only #c in4 ,in the cell system a series of cellular walls of wrought or cast iron are placed in a tank1 the distance between each pair of walls being from #ab to #af in41 according to the thickness of the block required4 ,this space is filled with the water to be frozen4 ,cold brine circulates through the cells1 and the ice forms on the outer surfaces1 gradually increasing in thickness until the two opposite layers meet and join together4 ,if thinner blocks are required1 the freezing process may be stopped at any time and the ice removed4 ,in order to detach the ice it is customary to cut off the supply of cold brine and circulate brine at a higher temperature through the cells4 ,ice frozen by either of the above described methods from ordinary water is more or less opaque1 owing to the air liberated during the freezing process1 little bubbles of which are caught in the ice as it forms1 and in order to produce transparent ice it is necessary that the water should be agitated during the freezing process in such a way as to permit the air bubbles to escape4 ,with the can system this is generally accomplished by means of arms having a vertical or horizontal movement4 ,these arms are either withdrawn as the ice forms1 leaving the block solid1 or they are made to work backward and forward in the center of the moulds1 dividing the block vertically into two pieces4 ,with the cell system agitation is generally effected by making a communication between the bottom of each water space and a chamber below1 in which a paddle or wood piston is caused to reciprocate4 ,the movement thus given to the water in the chamber is communicated to that in the process of being frozen1 and the small bubbles of air are in this way detached and set free4 ,the ice which first forms on the sides of the moulds or cells is1 as a rule1 sufficiently transparent even without agitation4 ,the opacity increases toward the center1 where the opposing layers join1 and it is1 therefore1 more necessary to agitate toward the end of the freezing process than at the commencement4 ,as the capacity for holding air in solution decreases if the temperature of the water is raised1 less agitation is needed in hot than in temperate climates4 ,experiments have been made from time to time with the view of producing transparent ice from distilled water1 and so dispensing with agitation4 ,in this case the cost of distilling the water will have to be added to the ordinary working expenses4 ,cooling of ,liquids4--,in breweries1 distilleries1 butter factories1 and other places where it is desired to have a supply of water or brine for cooling and other purposes at a comparatively low temperature1 refrigerating machines may be advantageously applied4 ,in this case the liquid is passed through the refrigerator and then utilized in any convenient manner4 ,cooling of ,rooms4--,for this purpose the usual plan is to employ a circulation of cold brine through rows of iron piping1 placed either on the ceiling or on the walls of the rooms to be cooled4 ,in this1 as in the other cases where brine is used1 it is employed merely as a medium for taking up heat at one place and transferring it to the ammonia in the refrigerator1 the ammonia in turn completing the operation by giving up the heat to the cooling water during liquefaction in the condenser4 ,the brine pipes cool the adjacent air1 which1 in consequence of its greater specific gravity1 descends1 being replaced by warmer air1 which in turn becomes cold1 and so the process goes on4 ,assuming the air to be sufficiently saturated1 which is generally the case1 some of the moisture in it is condensed and frozen on the surface of the pipes2 and if the air is renewed in whole or in part from the outside1 or if the contents of the chamber are wet1 the deposit of ice in the pipes will in time become so thick as to necessitate its being thawed off4 ,this is accomplished by turning a current of warm brine through the pipes4 ,another method has been proposed1 in which the brine pipes are placed in a separate compartment1 air being circulated through this compartment to the rooms1 and back again to the cooling pipes in a closed cycle by means of a fan4 ,this plan was tried on a large scale by ,mr4 ,chambers at the ,victoria ,docks1 but for some reason or other was abandoned4 ,one difficulty is the collection of ice from the moisture deposited from the air1 which clogs up the spaces between the pipes1 besides diminishing their cooling power4 ,this1 in some cases1 can be partially obviated by using the same air over again1 but in most instances special means would have to be provided for frequent thawing off1 the pipes having1 on account of economy of space and convenience1 to be placed so close together1 and to be so confined in surface1 that they are much more liable to have their action interfered with than when placed on the roof or walls of the room4 ,in addition to the foregoing there are1 of course1 many other applications of ammonia refrigerating machines of a more or less special nature1 of which time will not permit even a passing reference4 ,many of these are embraced in the second class1 cold water or brine being used for the cooling of candles1 the separation of paraffin1 the crystallization of salts1 and for many other purposes4 ,in the same way cold brine has been used with great success for freezing quicksand in the sinking of shafts1 the excavation being carried out and the watertight tubing or lining put in while the material is in a solid state4 ,in a paper such as this it would be quite impracticable to enter into details of construction1 and the author has therefore confined himself chiefly to principles of working4 ,in conclusion1 however1 it may be added that in ammonia machines1 whether on the absorption or compression systems1 no copper or alloy of copper can be used in parts subjected to the action of the ammonia4 ,cast or wrought iron and steel may1 however1 be used1 provided the quality is good1 but special care must be taken in the construction of those parts of absorption machines which are subjected to a high temperature4 ,in both classes of apparatus first-class materials and workmanship are most absolute essentials4 99 99 99 99 99 ,continued from ,supplement1 ,no4 #fdf1 p4 #ajcai4 ,,elements ,,of ,,architectural ,,design4#a ,footnote #a3 ,delivered before the ,society of ,arts1 ,london1 ,december #ac1 #ahhg4 ,from the ,journal of the ,society4 ,,by ,h4 ,h4 ,,statham4 ,,iii4--,,continued4 ,the ,romans1 in their arched constructions1 habitually strengthened the point against which the vault thrust by adding columnar features to the walls1 as shown in ,fig4 #ajh2 thus again making a false use of the column in a way in which it was never contemplated by those who originally developed its form4 ,in ,romanesque architecture the column was no longer used for this purpose2 its place was taken by a flat pilaster-like projection of the wall 7plan and section1 ,fig4 #aji71 which gave sufficient strength for the not very ambitious vaulted roofs of this period1 where often in fact only the aisles were vaulted1 and the center compartment covered with a wooden roof4 ,at first this pilaster-like form bore a reminiscence of a classic capital as its termination2 a moulded capping under the eaves of the building4 ,next this capping was almost insensibly dropped1 and the buttress became a mere flat strip of wall4 ,as the vaulting became bolder and more ambitious1 the buttress had to be made more massive and of greater projection1 to afford sufficient abutment to the vault1 more especially toward the lower part1 where the thrust of the roof is carried to the ground4 ,hence arose the tendency to increase the projection of the buttress gradually downward1 and this was done by successive slopes or set-offs1 as they are termed1 which assisted 7whether intentionally or not in the first instance7 in further aiding the correct architectural expression of the buttress4 ,then the vaulting of the center aisle was carried so high and treated in so bold a manner1 with a progressive diminution of the wall piers 7as the taste for large traceried windows developed more and more71 that a flying buttress 7see section1 ,fig4 #aaj7 was necessary to take the thrust across to the exterior buttresses1 and these again1 under this additional stress1 were further increased in projection1 and were at the same time made narrower 7to allow for all the window space that was wanted between them71 until the result was that the masses of wall1 which in the ,romanesque building were placed longitudinally and parallel to the axis of the building1 have all turned about 7,fig4 #aaj1 plan7 and placed themselves with their edges to the building to resist the thrust of the roofing4 ,the same amount of wall is there as in the ,romanesque building1 but it is arranged in quite a new manner1 in order to meet the new constructive conditions of the complete ,gothic building4 ,illustration3 ,figs4 #ajh-aad4 ,it will be seen thus how completely this important and characteristic feature of ,gothic architecture1 the buttress1 is the outcome of practical conditions of construction4 ,it is treated decoratively1 but it is itself a necessary engineering expedient in the construction4 ,the application of the same principle1 and its effect upon architectural expression1 may be seen in some other examples besides that of the buttress in its usual shape and position4 ,the whole arrangement and disposition of an arched building is affected by the necessity of providing counterforts to resist the thrust of arches4 ,the position of the central tower1 for instance1 in so many cathedrals and churches1 at the intersection of the nave and transepts1 is not only the result of a feeling for architectural effect and the centralizing of the composition1 it is the position in which also the tower has the cross walls of nave and transepts abutting against it in all four directions3 if the tower is to be placed over the central roof at all1 it could only be over this point of the plan4 ,in the ,norman buildings1 which in some respects were finer constructions than those of later ,gothic1 the desire to provide a firm abutment for the arches carrying the tower had a most marked effect on the architectural expression of the interior4 ,at ,tewkesbury1 for instance1 while the lower piers are designed in the usual way toward the north and south sides 7viz41 as portions of a pier of nearly square proportion standing under the angle of the tower71 in the east and west direction the tower piers run out into great solid masses of wall1 in order to insure a sufficient abutment for the tower arches4 ,on the north and south sides the solid transept walls were available immediately on the other side of the low arch of the side aisle1 but on the east and west sides there were only the nave and choir arcades to take the thrust of the north and south tower arches1 and so the ,normans took care to interpose a massive piece of wall between1 in order that the thrust of the tower arches might be neutralized before it could operate against the less solid arcaded portions of the walls4 ,this expedient1 this great mass of wall introduced solely for constructive reasons1 adds greatly to the grandeur of the interior architectural effect4 ,the true constructive and architectural perception of the ,normans in this treatment of the lower piers is illustrated by the curious contrast presented at ,salisbury4 ,there the tower piers are rather small1 the style is later1 and the massive building of the ,normans had given way to a more graceful but less monumental manner of building4 ,still the abutment of the tower arches was probably sufficient for the weight of the tower as at first built2 but when the lofty spire was put on the top of this1 its vertical weight1 pressing upon the tower arches and increasing their horizontal thrust1 actually thrust the nave and choir arcades out of the perpendicular toward the west and east respectively1 and there they are leaning at a very perceptible angle away from the center of the church--the architectural expression1 in a very significant form1 of the neglect of balance of mass in construction4 ,but while the buttress in ,gothic architecture has been in process of development1 what has the vault been doing8 ,we left it 7,fig4 #ib7 in the condition of a round wagon vault1 intersected by another similar vault at right angles4 ,by that method of treatment we got rid of the continuous thrust on the walls4 ,but there were many difficulties to be faced in the construction of vaulting after this first step had been taken1 difficulties which arose chiefly from the rigid and unmanageable proportions of the circular arch1 and which could not be even partially solved till the introduction of the pointed arch4 ,the pointed arch is the other most marked and characteristic feature of ,gothic architecture1 and1 like the buttress1 it will be seen that it arose entirely out of constructive difficulties4 ,these difficulties were of two kinds2 the first arose from the tendency of the round arch1 when on a large scale and heavily weighted1 to sink at the crown if there is even any very slight settlement of the abutments4 ,if we turn again to diagram #gg1 and observe the nearly vertical line formed there by the joints of the keystone1 and if we suppose the scale of that arch very much increased without increasing the width of each voussoir1 and suppose it built in two or three rings one over the other 7which is really the constructive method of a ,gothic arch71 we shall see that these joints in the uppermost portion of the arch must in that case become still more nearly vertical2 in other words1 the voussoirs almost lose the wedge shape which is necessary to keep them in their places1 and a very slight movement or settlement of the abutments is sufficient to make the arch stones lose some of their grip on each other and sink more or less1 leaving the arch flat at the crown4 ,there can be no doubt that it was the observance of this partial failure of the round arch 7partly owing probably to their own careless way of preparing the foundations for their piers--for the medival builders were very bad engineers in that respect7 which induced the builders of the early transitional abbeys1 such as ,furness and ,fountains and ,kirkstall1 to build the large arches of the nave pointed1 though they still retain the circular-headed form for the smaller arches in the same buildings1 which were not so constructively important4 ,this is one of the constructive reasons which led to the adoption of the pointed arch in medival architecture1 and one which is easily stated and easily understood4 ,the other influence is one arising out of the lengthened conflict with the practical difficulties of vaulting1 and is a rather more complicated matter1 which we must now endeavor to follow out4 ,illustration3 ,figs4 #ic-ajg4 ,looking at ,fig4 #ib1 it will be seen that in addition to the perspective sketch of the intersecting arches1 there is drawn under it a plan1 which represents the four points of the abutment of the arches 7identified in plan and perspective sketch as ,a1 ,b1 ,c1 ,d71 and the lines which are taken by the various arches shown by dotted lines4 ,looking at the perspective sketch1 it will be apparent that the intersection of the two cross vaults produces two intersecting arches1 the upper line of which is shown in the perspective sketch 7marked e and f72 underneath1 this intersection of the two arches1 which forms a furrow in the upper side of the construction1 forms an edge which traverses the space occupied by the plan of the vaulting as two oblique arches1 running from ,a to ,c and from ,b to ,d on the plan4 ,although these are only lines formed by the intersection of two cross arches1 still they make decided arches to the eye1 and form prominent lines in the system of vaulting2 and in a later period of vaulting they were treated as prominent lines and strongly emphasized by mouldings2 but in the ,roman and early ,romanesque vaults they were simply left as edges1 the eye being directed rather to the vaulting surfaces than to the edges4 ,the importance of this distinction between the vaulting surfaces and their meeting edges or groins#b will be seen just now4 ,the edges1 nevertheless1 as was observed1 do form arches1 and we have therefore a system of cross arches 7,a ,b and ,c ,d#c ,fig4 #ie71 two wall arches 7,a1 ,d and ,b ,c71 and two oblique arches 7,a ,c and ,b ,d71 which divide the space into four equal triangular portions2 this kind of vaulting being hence called quadripartite vaulting4 ,in this and the other diagrams of arches on this page1 the cross arches are all shown in positive lines1 and the oblique arches in dotted lines4 ,footnote #b3 ,a groin is the edge line formed by the meeting and intersection of any two arched surfaces4 ,when this edge line is covered and emphasized by a band of moulded stones forming an arch1 as it were1 on this edge1 this is called a groin rib4 ,footnote #c3 ,the ,d seems to have been accidentally omitted in this diagram2 it is of course the fourth angle of the plan4 ,we have here a system in which four semicircular arches of the width of ,a ,b are combined with two oblique arches of the width of ,a ,c1 springing from the same level and supposed to rise to the same height4 ,but if we draw out the lines of these two arches in a comparative elevation1 so as to compare their curves together1 we at once find we are in a difficulty4 ,the intersection of the two circular arches produces an ellipse with a very flat crown1 and very liable to fail4 ,if we attempt to make the oblique arch a segment only of a large circle1 as in the dotted line at #id1 so as to keep it the same level as the other without being so flat at the top1 the crown of the arch is safer1 but this can only be done at the cost of getting a queer twist in the line of the oblique arch1 as shown at ,d1 ,fig4 #ic4 ,the like result of a twist of the line of the oblique arch would occur if the two sides of the space we are vaulting over were of different lengths1 i4e4 if the vaulting space were otherwise than a square1 as long as we are using circular arches4 ,if we attempt to make the oblique arches complete circles1 as at ,fig4 #if1 we see that they must necessarily rise higher than the cross and side arches1 so that the roof would be in a succession of domical forms1 as at ,fig4 #ig4 ,there is the further expedient of stilting the cross arches1 that is1 making the real arch spring from a point above the impost and building the lower portion of it vertical1 as shown in ,fig4 #ih4 ,this device of stilting the smaller arches to raise their crowns to the level of those of the larger arches was in constant use in ,byzantine and early ,romanesque architecture1 in the kind of manner shown in the sketch1 ,fig4 #ii2 and a very clumsy and makeshift method of dealing with the problem it is2 but something of the kind was inevitable as long as nothing but the round arch was available for covering contiguous spaces of different widths4 ,the whole of these difficulties were approximately got over in theory1 and almost entirely in practice1 by the adoption of the pointed arch4 ,by its means1 as will be seen in ,fig4 #ajj1 arches over spaces of different widths could be carried to the same height1 yet with little difference in their curves at the springing1 and without the necessity of employing a dangerously flat elliptical form in the oblique arch4 ,a sketch of the ,gothic vault in this form1 and as the intersection of the surfaces of pointed vaults1 is shown in ,fig4 #aja4 ,but now another and most important change was to come over the vault4 ,the medival architects were not satisfied with the mere edge left by the ,romans in their vaults1 and even before the full ,gothic period the ,roman builders had emphasized their oblique arches in many cases by ponderous courses of moulded or unmoulded stone in the form of vaulting ribs4 ,these1 in the case of ,norman building1 were probably not merely put for the purpose of architectural expression1 but also because they afforded an opportunity of concealing behind the lines of a regularly curved groin rib the irregular curves which were really formed by the junction of the vaulting surfaces4 ,but when the vault become more manageable in its curves after the adoption of the pointed arch1 the groin rib became adopted in the early pointed vaulting as a means of giving expression and carrying up the lines of the architectural design4 ,on its edge were stones moulded with the deep undercut hollows of early ,english moulding1 defining the curves of the oblique as well as of the cross arches with strongly marked lines1 and1 moreover1 falling on a level with each other in architectural importance2 the oblique vault of the arch is no longer a secondary line in the vaulting design2 on the contrary1 the cross arches are usually omitted1 as shown in ,figs4 #ajb and #ajc 7view and plan of an early ,gothic quadripartite vault72 so that the cross rib1 which1 in the early ,romanesque wagon vault 7,fig4 #ij71 was the one marked line on the vaulting surface1 has now been obliterated1 and the line of the oblique arch 7,e ,f1 ,figs4 #ajb1 #ajc7 has taken its place4 ,the effect of the strongly marked lines of the groin ribs1 radiating from the cap of the shaft which was their architectural support1 seems to have been so far attractive to the medival builders that they soon endeavored to improve upon it and carry it further by multiplying the groin ribs4 ,one of the stages of this progress is shown in ,figs4 #ajd1 #aje4 ,here it will be seen that the cross rib is again shown1 and that intermediate ribs have been introduced between it and the oblique rib4 ,the richness of effect of the vault is much heightened thereby2 but a very important modification in the mode of constructing it has been introduced4 ,as the groin ribs become multiplied1 it came to be seen that it was easier to construct them first1 and fill in the spaces afterward2 accordingly the groin1 instead of being1 as it was in the early days of vaulting1 merely the line formed by the meeting of two arch surfaces1 became a kind of stone scaffolding or frame work1 between which the vaulting surfaces were filled in with lighter material4 ,this arrangement of course made an immense difference in the whole principle of constructing the vault1 and rendered it much more ductile in the hands of the builder1 more capable of taking any form which he wished to impose on it1 than when the vault was regarded and built as an intersection of surfaces4 ,there was still one difficulty1 however1 one slight failure both practical and theoretical in the vault architecture1 which for a long time much exercised the minds of the builders4 ,the ribs of the vaulting being all of unequal length1 they had to assume different curves almost immediately on rising from the impost2 and as the mouldings of the ribs have to be run into each other 7mitered is the technical term7 on the impost1 there not being room to receive them all separately1 it was almost impossible to get them to make their divergence from each other in a completely symmetrical manner2 the shorter ribs with the quicker curves parted from each other at a lower point than the larger ones1 and the miters occurred at unequal heights4 ,the effort to get over this unsatisfactory and irregular junction of the ribs at the springing was made first by setting back the feet of the shorter ribs on the impost capping1 somewhat in the rear of the feet of the larger ribs1 so as to throw their parting point higher up2 but this also was only a makeshift1 which it was hoped the eye would pass over2 and in fact it is rarely noticeable except to those who know about it and look for it4 ,still the defect was there1 and was not got over until the idea occurred of making all the ribs of the same curvature and the same length1 and intercepting them all by a circle at the apex of the vault1 as shown in ,figs4 #ajf1 #ajg2 the space between the circles at the apex of the vault being practically a nearly flat surface or plafond held in its place by the arches surrounding it2 though1 for effect1 it is often treated otherwise in external appearance1 being decorated by pendants giving a reversed curve at this point1 but which of course are only ornamental features hung from the roof4 ,if we look again at ,fig4 #ajd1 we shall see that this was a very natural transition after all1 for the arrangement of the ribs and vaulting surfaces in that example is manifestly suggestive of a form radiating round the central point of springing1 though it only suggests that1 and does not completely realize it4 ,but here came a further and very curious change in the method of building the vault1 for as the ribs were made more numerous1 for richness of effect1 in this form of vaulting1 it was discovered that it was much easier to build the whole as a solid face of masonry1 working the ribs on the face of it4 ,thus the ribs1 which in the intermediate period were the constructive framework of the vault1 in the final form of fan vaulting came back to their original use as merely a form of architectural expression1 meant to carry on the architectural lines of the design2 and they perform1 on a larger scale and with a different expression1 much the same kind of function which the fluting lines performed in the ,greek column4 ,the fan vault is therefore a kind of inverted dome1 built up in courses on much the same principle as a dome1 but a convex curve internally1 instead of a concave one1 the whole forming a series of inverted conoid forms abutting against the wall at the foot and against each other at their upper margins4 ,this form of roof is wonderfully rich in effect1 and has the appearance of being a piece of purely artistic work done for the pleasure of seeing it2 yet1 as we have seen1 it is in reality1 like almost everything good in architecture1 the logical outcome of a contention with structural problems4 ,we have already noticed the suggestion1 in early ,gothic or ,romanesque1 of the dividing up of a pier into a multiple pier1 of which each part supports a special member of the superstructure1 as indicated in ,fig4 #ij4 ,the ,gothic pier1 in its development in this respect1 affords a striking example of that influence of the superstructure on the plan which has before been referred to4 ,the peculiar manner of building the arch in ,gothic work led almost inevitably to this breaking up of the pier into various members4 ,the ,roman arch was on its lower surface a simple flat section1 the decorative treatment in the way of mouldings being round the circumference1 and not on the under side or soffit of the arch1 and in early ,romanesque work this method was still followed4 ,the medival builders1 partly in the first instance because they built with smaller stones1 adopted at an early period the plan of building an arch in two or more courses or rings1 one below and recessed within the other4 ,as the process of moulding the arch stones became more elaborated1 and a larger number of subarches one within another were introduced1 this characteristic form of subarches became almost lost to the eye in the multiplicity of the mouldings used4 ,but up to nearly the latest period of ,gothic architecture this form may still be traced1 if looked for1 as the basis of the arrangement of the mouldings1 which are all formed by cutting out of so many square sections1 recessed one within the other4 ,this will be more fully described in the next lecture4 ,we are now speaking more especially of the pier as affected by this method of building the arches in recessed orders4 ,if we consider the effect of bringing down on the top of a square capital an arch composed of two rings of squared stones1 the lower one only half the width 7say7 of the upper one1 it will be apparent that on the square capital the arch stones would leave a portion of the capital at each angle bare1 and supporting nothing4#d ,this looks awkward and illogical1 and accordingly the pier is modified so as to suit the shape of the arch4 ,figs4 #aaa1 #aab1 #aac1 and #aad1 with the plans1 ,b ,c ,d1 accompanying them1 illustrate this development of the pier4 ,fig4 #aaa is a simple cylindrical pier with a coarsely formed capital1 a kind of reminiscence of the ,doric capital1 with a plain ,romanesque arch starting from it4 ,fig4 #aab1 shown in plan at ,b1 is the kind of form 7varied in different examples7 which the pier assumed in ,norman and early ,french work1 when the arch had been divided into two recessed orders4 ,the double lines of the arch are seen springing from the cap each way1 in the elevation of the pier4 ,if we look at the plan of the pier1 we see that1 in place of the single cylinder1 it is now a square with four smaller half cylinders1 one on each face4 ,of these1 those on the right and left of the plan support the subarches of the arcade2 the one on the lower side1 which we will suppose to be looking toward the nave1 supports the shaft which carries the nave vaulting1 and which stands on the main capital with a small base of its own1 as seen in ,fig4 #aab--;a common feature in early work2 and the half column on the upper side of the plan supports the vaulting rib of the aisle4 ,in ,fig4 #aac and plan ,c1 which represents a pier of nearly a century later1 we see that the pier is broken up by perfectly detached shafts1 each with its own capital1 and each carrying a group of arch mouldings1 which latter have become more elaborated4 ,fig4 #aad and plan ,d show a late ,gothic fourteenth century pier1 in which the separate shafts have been abandoned1 or rather absorbed into the body of the pier1 and the pier is formed of a number of moulded projections1 with hollows giving deep shadows between them1 and the capitals of the various members run into one another1 forming a complete cap round the pier4 ,this pier shows a remarkable contrast in every way to ,b1 yet it is a direct development from the latter4 ,in this late form of pier1 it will be observed that the projection1 ,e1 which carries the vaulting ribs of the nave1 instead of springing from the capital1 as in the early example1 ,fig4 #aaa1 springs from the floor1 and runs right up past the capital2 thus the plan of the vaulting is brought1 as it were1 down on to the floor1 and the connection between the roofing of its building and its plan is as complete as can well be4 ,in ,fig4 #aac the vaulting shaft is supposed to stop short of the capital and to spring from a corbel in the wall1 situated above the limit of the drawing4 ,this was a common arrangement in the ,early ,english and ,early ,decorated periods of ,gothic1 but it is not so logical and complete1 or so satisfactory either to the eye or to the judgment1 as starting the vaulting shaft from the floor line4 ,the connection between the roofing and the plan may be further seen by looking at the portion of a medival plan given under ,fig4 #aaj1 where the dotted lines represent the course of the groin ribs of the roof above4 ,it will be seen how completely these depend upon the plan1 so that it is necessary to determine how the roof in a vaulted building is to be arranged before setting out the ground plan4 ,footnote #d3 ,this was illustrated by diagrams on the wall at the delivery of the lecture4 ,thus we see that the ,gothic cathedral1 entirely different in its form from that of the ,greek temple1 illustrates1 perhaps1 even more completely than the ,greek style1 the same principle of correct and truthful expression of the construction of the building1 and that all the main features which give to the style its most striking and picturesque effects are not arbitrarily adopted forms1 but are the result of a continuous architectural development based on the development of the construction4 ,the decorative details of the ,gothic style1 though differing exceedingly from those of the ,greek1 are1 like the latter1 conventional adaptations of suggestions from nature2 and in this respect again1 as well as in the character of the mouldings1 we find both sides illustrating the same general principle in the design of ornament1 in its relation to position1 climate1 and material2 but this part of the subject will be more fully treated of in the next lecture4 ,we have now arrived at a style of architectural construction and expression which seems so different from that of ,greek architecture1 which we considered in the last lecture1 that it is difficult to realize at first that the one is1 in regard to some of its most important features1 a lineal descendant of the other4 ,yet this is unquestionably the case4 ,the long thin shaft of ,gothic architecture is descended1 through a long series of modifications1 from the single cylindrical column of the ,greek2 and the carved medival capital1 again1 is to be traced back to the ,greek ,corinthian capital1 through examples in early ,french architecture1 of which a tolerably complete series of modifications could be collected1 showing the gradual change from the first deviations of the early ,gothic capital from its classical model1 while it still retained the square abacus and the scroll under the angle and the symmetrical disposition of the leaves1 down to the free and unconstrained treatment of the later ,gothic capital4 ,yet with these decided relations in derivation1 what a difference in the two manners of building6 ,the ,greek building is comparatively small in scale1 symmetrical and balanced in its main design1 highly finished in its details in accordance with a preconceived theory4 ,the ,gothic building is much more extensive in scale1 is not necessarily symmetrical in its main design1 and the decorative details appear as if worked according to the individual taste and pleasure of each carver1 and not upon any preconceived theory of form or proportion4 ,in the ,greek building all the predominant lines are horizontal2 in the medival building they are vertical4 ,in the ,greek building every opening is covered by a lintel2 in the ,gothic building every opening is covered by an arch4 ,no two styles1 it might be said1 could be more strongly contrasted in their general characteristics and appearance4 ,yet this very contrast only serves to emphasize the more strongly the main point which ,i have been wishing to keep prominent in these lectures--that architectural design1 rightly considered1 is based on and is the expression of plan and construction4 ,in ,greek columnar architecture the salient feature of the style is the support of a cross lintel by a vertical pillar2 and the main effort of the architectural designer is concentrated on developing the expression of the functions of these two essential portions of the structure4 ,the whole of the openings being bridged by horizontal lintels1 the whole of the main lines of the superstructure are horizontal1 and their horizontal status is as strongly marked as possible by the terminating lines of the cornice--the whole of the pressures of the superstructure are simply vertical1 and the whole of the lines of design of the supports are laid out so as to emphasize the idea of resistance to vertical pressure4 ,the ,greek column1 too1 has only one simple office to perform1 that of supporting a single mass of the superstructure1 exercising a single pressure in the same direction4 ,in the ,gothic building the main pressures are oblique and not vertical1 and the main feature of the exterior substructure1 the buttress1 is designed to express resistance to an oblique pressure2 and no real progress was made with the development of the arched style until the false use of the apparent column or pilaster as a buttress was got rid of1 and the true buttress form evolved4 ,on the interior piers of the arcade there is a resolution of pressures which practically results in a vertical pressure1 and the pier remains vertical2 but the pressure upon it being the resultant of a complex collection of pressures1 each of these has1 in complete ,gothic1 its own apparent vertical supporting feature1 so that the plan of the substructure becomes a logical representation of the main features and pressures of the superstructure4 ,the main tendency of the pointed arched building is toward vertically1 and this vertical tendency is strongly emphasized and assisted by the breaking up of the really solid mass of the pier into a number of slender shafts1 which1 by their strongly marked parallel lines1 lead the eye upward toward the closing-in lines of the arcade and of the vaulted roof which forms the culmination of the whole4 ,the ,greek column is also assisted in its vertical expression by the lines of the fluting2 but as the object of these is only to emphasize the one office of the one column1 they are strictly subordinate to the main form1 are in fact merely a kind of decorative treatment of it in accordance with its function4 ,in the ,gothic pier the object is to express complexity of function1 and the pier1 instead of being a single fluted column1 is broken up into a variety of connected columnar forms1 each expressive of its own function in the design4 ,it may be observed also that the ,gothic building1 like the ,greek1 falls into certain main divisions arising out of the practical conditions of its construction1 and which form a kind of order analogous to the classic order in a sense1 though not governed by such strict conventional rules4 ,the classic order has its columnar support1 its beam1 its frieze for decorative treatment4 ,the ,gothic order has its columnar support1 its arch 7in place of the beam71 its decoratively treated stage 7the triforium71 occupying the space against which the aisle roof abuts1 and its clerestory1 or window stage4 ,all these arise as naturally out of the conditions and historical development of the structure in the ,gothic case as in the ,greek one1 but the ,greek order is an external1 the ,gothic an internal one4 ,the two styles are based on constructive conditions totally different the one from the other2 their expression and character are totally different4 ,but this very difference is the most emphatic declaration of the same principle1 that architectural design is the logical1 but decorative1 expression of plan and construction4 99 99 99 99 99 ,,the ,,meteorological ,,station ,,on ,,mt4 ,,santis4 ,illustration ,at the second ,international ,meteorological ,congress1 in #ahgi1 the erection of an observatory on the top of a high mountain was considered4 ,the ,swiss ,meteorological ,commission undertook to carry out the project1 and sent out circulars to different associations1 governments1 and private individuals requesting single or yearly contributions to aid in defraying the expense of the station4 ,in ,december1 #ahha1 an extra credit of about #a1jjj was granted by the ,bundesversammlung for the initial work on the station1 which was temporarily placed in the ,santis ,hotel1 and a telegraph was put up between that place and ,weisbad in ,august1 #ahhb1 so that on ,september #a of the same year the meteorological observations were begun4 ,at the end of ,august1 #ahhe1 this temporary arrangement expired1 and the enterprise could not be carried on unless the support of the same was undertaken by the ,union4 ,on ,march #bg1 #ahhe1 the ,bundesversammlung decided to take the necessary steps4 ,mr4 ,fritz ,brunner1 who died ,may #a1 #ahhe1 left a large legacy for the enterprise1 making it possible to build a special observatory4 ,for this purpose the northeast corner of the highest rocky peak was blasted out and the building was so placed that the wall of rock at the rear formed an excellent protection from the high west winds4 ,by the first of ,october1 last year1 the building was ready for occupancy1 and there was a quiet opening at which ,mr4 ,potch1 director of the ,blue ,hill ,observatory1 near ,boston1 and others were present4 ,the building is #bf feet long1 #ai feet deep1 and #cj feet high1 and is very solid and massive1 having been built of the limestone blasted from the rock4 ,it consists of a ground floor containing the telegraph office1 the observers' work room1 and the kitchen and store rooms2 the first story1 in which are the living and sleeping rooms for the observers and their assistants2 and the second story1 living and sleeping rooms for visiting scientists who come to make special observations1 and a reserve room4 ,the barometer and barograph are placed in the second story1 at a height of about #h1bjb feet above the level of the sea1 whereas in the hotel they were only about #h1jic feet above the sea level4 ,the flat roof1 of wood and cement1 which extends very little above the plateau of the mountain top1 is admirably adapted for making observations in the open air4 ,all the rooms in the house are ceiled with wood1 and the walls and floors of the ground floor and first story and the ceilings of the second story are covered with insulating material4 ,the cost of the building1 including the equipments1 amounted to about #aa1bjj4 ,the fact that since the erection of the ,santis station there has been a still higher station constructed on ,sonnblick 7#aj1acg feet high7 does not decrease the value of the former1 for the greater the number of such elevated stations1 the better will be the meteorological investigations of the upper air currents4 ,the present observer at ,santis is ,mr4 ,c4 ,saxer1 who has endured the hardships and privations of a long winter at the station4 ,the anemometer house1 which is shown in our illustration1 is connected with the main house by a tunnel4 ,several times during the day records are taken of the barometer1 the thermometer1 the weather vane1 as well as notes in regard to the condition of the weather1 the clouds1 fall of rain or snow1 etc4 ,a registering aneroid barometer marks the pressure of the atmosphere hourly1 and two turning thermometers register the temperature at midnight and at four o'clock in the morning4--,illustrirte ,zeitung4 99 99 99 99 99 ,,the ,,care ,,of ,,the ,,eyes4#a ,footnote #a3 ,from a paper by ,david ,webster4 ,m4,d41 professor of ophthalmology in the ,new ,york ,polyclinic and surgeon to the ,manhattan ,eye and ,ear ,hospital1 ,new ,york4 ,,by ,,prof4 ,,david ,,webster1 ,m4,d4 ,the light of the body is the eye4 ,of all our senses1 sight1 hearing1 touch1 taste1 and smell1 the sight is that which seems to us the most important4 ,through the eye1 the organ of vision1 we gain more information and experience more pleasure1 perhaps1 than through any or all our other organs of sense4 ,indeed1 we are apt to depreciate the value of our other senses when comparing them to the eyesight4 ,it is not uncommon to hear a person say1 ,i would rather die than be blind4 ,but no one says1 ,i would rather die than lose my hearing4 ,as a matter of fact1 the person who is totally blind generally appears to be more cheerful1 happier1 than one who is totally deaf4 ,deaf mutes are often dull1 morose1 quick tempered1 obstinate1 self-willed1 and difficult to get along with1 while the blind are not infrequently distinguished for qualities quite the reverse4 ,it is worthy of remark that the eye is that organ of sense which is most ornamental as well as useful1 and the deprivation of which constitutes the most visible deformity4 ,but it is unnecessary to enter into a comparison of the relative value of our senses or the relative misfortune of our loss of any one of them4 ,we need them all in our daily struggle for existence1 and it is necessary to our physical and mental well-being1 as well as to our success in life1 that we preserve them all in as high a degree of perfection as possible4 ,we must not lose sight of the fact that all our organs of sense are parts of one body1 and that whatever we do to improve or preserve the health of our eyes cannot do harm to any other organ4 ,we shall be able to take care of our eyes more intelligently if we know something of their structure and how they perform their functions4 ,the eye is a hollow globe filled with transparent material and set in a bony cavity of the skull1 which1 with the eyelids and eyelashes1 protect it from injury4 ,it is moved at will in every direction by six muscles which are attached to its surface1 and is lubricated and kept moist by the secretions of the tear gland and other glands1 which secretions1 having done their work1 are carried down into the nose by a passage especially made for the purpose--the tear duct4 ,we are all familiar with the fact that our eyes are to see with1 but in order to be able to take care of our eyes intelligently1 it is necessary to understand as far as possible how to see with them4 ,,the ,,back ,,wall ,,of ,,the ,,eye4 ,it is a remarkable fact that every object we see has its picture formed upon the back wall of our eyes4 ,the eye is a darkened chamber1 and the whole of the front part of it acts as a lens to bring the rays of light coming from objects we wish to see to a focus on its back wall1 thus forming a picture there as distinct as the picture formed in the camera obscura of the photographer4 ,this has not only been proved by the laws of optics1 but has been actually demonstrated in the eyes of rabbits and other animals4 ,experimenters have held an object before the eye of a rabbit for a few moments1 and have then killed the animal and removed the eye as quickly as possible1 and laid its back wall bare1 and have distinctly seen there the picture of the object upon which the eye had been fixed4 ,it is a truly wonderful fact that these pictures upon the back wall of the eye can be changed so rapidly that the picture of the object last looked at disappears in an instant and makes way for the picture of the next4 ,we know that the picture formed on the back wall of the eye is carried back to the brain by the optic nerve1 but there our knowledge stops4 ,science cannot tell us how the brain1 and through it the mind1 completes the act of seeing4 ,it is there that the finite and the infinite touch1 and1 as our minds are finite1 we cannot comprehend the infinite4 ,but there is enough that we can understand1 and it shall be my endeavor in this paper to make some plain statements that will help as a guide in the preservation of those wonderful and useful organs4 ,,far ,,and ,,near ,,sightedness4 ,we have to use our eyes for near and far distant vision4 ,in gathering pictures of distant objects the normally shaped eye puts forth little or no effort4 ,it is the near work1 such as reading1 sewing1 or drawing1 that puts a real muscular strain upon the eyes4 ,there are certain rules that apply to the use of the eyes for such near work regardless of the age of the person4 ,,reading4 #a4 ,in reading1 a book or newspaper should be held at a distance of from ten to fifteen inches from the eyes4 ,it is hardly necessary to caution anybody not to hold the print further away than fifteen inches4 ,the only objection to holding ordinary print too far away is that in so doing the pictures formed on the back wall of the eye are too small to be readily and easily perceived1 and the close attention consequently necessary causes both the eyes and the brain to tire4 ,most persons quickly find this out themselves1 and the tendency is rather to hold the book too near1 for the nearer the object to the eye1 the larger its picture upon the retina1 or back eye wall4 ,but here we encounter another danger4 ,the nearer the object the eyes are concentrated upon1 the greater the muscular effort necessary2 so that by holding the book too near1 the labor of reading is greatly increased1 and the long persistence in such a habit is likely to produce weak eyes1 and may1 in some instances1 lead to real near-sightedness4 ,when children are observed to have acquired this habit and cannot be persuaded out of it1 they should always be taken to a physician skilled in the treatment of the eye for examination and advice4 ,a little attention at such a time may save them from a whole lifetime of trouble with their eyes4 ,of course1 the larger the print1 the farther it may be held from the eyes4 ,,position4 #b4 ,the position of the person with regard to the light should be so that the latter will fall upon the page he is reading1 and not upon his eyes4 ,it is generally considered most convenient to have the light shine over the left shoulder1 so that in turning the leaves of the book1 the shadow of the hand upon the page is avoided4 ,it is not always possible to do this1 however1 and1 at the same time1 to get plenty of light upon the page4 ,when one finds himself compelled to face the light in reading1 or in standing at a desk bookkeeping1 he should always contrive to shade his eyes from a direct light4 ,this may be done with a large eye shade projecting from the brow4 ,a friend of mine1 a physician1 is very fond of reading by a kerosene lamp1 the lamp being placed on a table by his side1 and the direct light kept from his eyes by means of a piece of cardboard stuck up by the lamp chimney4 ,,proper ,,light4 #c4 ,the illumination should always be sufficient4 ,nothing is more injurious to the eyes than reading by a poor light4 ,many persons strain their eyes by reading on into the twilight as long as they possibly can4 ,they become interested and do not like to leave off4 ,some read in the evening at too great a distance from the source of light1 forgetting that the quantity of light diminishes as the square of the distance from the source of light increases4 ,thus1 at four feet1 one gets only one-sixteenth part of the light upon his page that he would at one foot4 ,it is the duty of parents and others who have charge of children to see to it that they do not injure their eyes by reading by insufficient light1 either daylight or artificial light4 ,there is a common notion that electric light is bad for the eyes4 ,the only foundation ,i can think of for such a notion is that it is trying to the eyes to gaze directly at the bright electric light4 ,it is bad to gaze long at any source of light1 and the brighter the source of light gazed at1 the worse for the eyes1 the sun being the worst of all4 ,i have seen more than one person whose eyes were permanently injured by gazing at the sun1 during an eclipse or otherwise4 ,as a matter of fact1 nothing short of sunlight is better than the incandescent electric light to read by or to work by4 ,,reading ,,in ,,bed4 ,as to reading while lying down in bed or on a lounge1 ,i can see no objection to it so far as the eyes are concerned1 provided the book is held in such a position that the eyes do not have to be rolled down too far4 ,unless the head is raised very high by pillows1 however1 it will be found very fatiguing to hold the book high enough1 not to mention the danger of falling asleep1 and of upsetting the lamp or candle1 and thus setting the bed on fire4 ,many persons permanently weaken their eyes by reading to pass away the tedious hours during recovery from severe illness4 ,the muscles of the eyes partake of the general weakness and are easily overtaxed4 ,persons in this condition may be read to1 but should avoid the active use of their own eyes4 ,,reading ,,in ,,rail ,,cars4 ,reading while in the rail cars or in omnibuses is to be avoided4 ,the rapid shaking1 trembling or oscillating motion of the cars makes it very difficult to keep the eyes fixed upon the words1 and is very tiresome4 ,i have seen many persons who attributed the failure of their eyes to the daily habit of reading while riding to and from the city4 ,children should be cautioned against reading with the head inclined forward4 ,the stooping position encourages a rush of blood to the head1 and consequently the eyes become congested1 and the foundations for near-sightedness are laid4 7,to be continued47 99 99 99 99 99 ,,testing ,,indigo ,,dyes4 ,the author deals with the question whether a sample of goods is dyed with indigo alone or with a mixture of indigo and other blue coloring matters4 ,his method may be summarized as follows3 ,threads of the material in question should give up no coloring matter to boiling water4 ,alcohol at #ej and at #ie per cent4 7by volume7 ought to extract no color1 even if gently warmed 7not boiled74 ,solution of oxalic acid saturated in the cold1 solution of borax1 solution of alum at #aj per cent41 and solution of ammonium molybdate at #cc-a_/c per cent4 ought not to extract any coloring matter at a boiling heat4 ,the borax extract1 if subsequently treated with hydrochloric acid1 should not turn red1 nor become blue on the further addition of ferric chloride4 ,solutions of stannous chloride and ferric chloride with the aid of heat ought entirely to destroy the blue coloring matter4 ,glacial acetic acid on repeated boiling should entirely dissolve the coloring matter4 ,if the acetic extracts are mixed with two volumes of ether and water is added1 so as to separate out the ether1 the water should appear as a slightly blue solution1 the main bulk of the indigo remaining in suspension at the surface of contact of the ethereal and watery stratum4 ,this acid watery stratum should be colorless1 and should not assume any color if a little strong hydrochloric acid is allowed to fall into it through the ether4 ,no sulphureted hydrogen should be evolved on boiling the yarn or cloth in strong hydrochloric acid4 ,on prolonged boiling1 supersaturation with strong potassa in excess1 heating and adding a few drops of chloroform1 no isonitrile should be formed4--,w4 ,lenz4 99 99 99 99 99 ,,the ,,scientific ,,american ,,architects ,,and ,,builders ,,edition4 #b4ej a ,year4 ,single ,copies1 #be cts4 ,this is a ,special ,edition of the ,scientific ,american1 issued monthly--on the first day of the month4 ,each number contains about forty large quarto pages1 equal to about two hundred ordinary book pages1 forming1 practically1 a large and splendid ,,magazine ,,of ,,architecture1 richly adorned with elegant plates in colors and with fine engravings1 illustrating the most interesting examples of modern ,architectural ,construction and allied subjects4 ,a special feature is the presentation in each number of a variety of the latest and best plans for private residences1 city and country1 including those of very moderate cost as well as the more expensive4 ,drawings in perspective and in color are given1 together with full ,plans1 ,specifications1 ,costs1 ,bills of ,estimate1 and ,sheets of ,details4 ,no other building paper contains so many plans1 details1 and specifications regularly presented as the ,scientific ,american4 ,hundreds of dwellings have already been erected on the various plans we have issued during the past year1 and many others are in process of construction4 ,architects1 ,builders1 and ,owners will find this work valuable in furnishing fresh and useful suggestions4 ,all who contemplate building or improving homes1 or erecting structures of any kind1 have before them in this work an almost endless series of the latest and best examples from which to make selections1 thus saving time and money4 ,many other subjects1 including ,sewerage1 ,piping1 ,lighting1 ,warming1 ,ventilating1 ,decorating1 ,laying out of ,grounds1 etc41 are illustrated4 ,an extensive ,compendium of ,manufacturers' ,announcements is also given1 in which the most reliable and approved ,building ,materials1 ,goods1 ,machines1 ,tools1 and ,appliances are described and illustrated1 with addresses of the makers1 etc4 ,the fullness1 richness1 cheapness1 and convenience of this work have won for it the ,,largest ,,circulation of any ,architectural publication in the world4 ,,munn ,,co41 ,,publishers1 #cfa ,,broadway1 ,,new ,,york4 99 99 99 99 99 ,a ,catalogue of valuable books on ,architecture1 ,building1 ,carpentry1 ,masonry1 ,heating1 ,warming1 ,lighting1 ,ventilation1 and all branches of industry pertaining to the art of ,building1 is supplied free of charge1 sent to any address4 99 99 99 99 99 ,,building ,,plans ,,and ,,specifications4 ,in connection with the publication of the ,building ,edition of the ,,scientific ,,american1 ,messrs4 ,munn ,co4 furnish plans and specifications for buildings of every kind1 including ,churches1 ,schools1 ,stores1 ,dwellings1 ,carriage ,houses1 ,barns1 etc4 ,in this work they are assisted by able and experienced architects4 ,full plans1 details1 and specifications for the various buildings illustrated in this paper can be supplied4 ,those who contemplate building1 or who wish to alter1 improve1 extend1 or add to existing buildings1 whether wings1 porches1 bay windows1 or attic rooms1 are invited to communicate with the undersigned4 ,our work extends to all parts of the country4 ,estimates1 plans1 and drawings promptly prepared4 ,terms moderate4 ,address ,,munn ,,co41 #cfa ,,broadway1 ,,new ,,york4 99 99 99 99 99 ,,the ,,scientific ,,american ,,supplement4 ,,published ,,weekly4 ,terms of ,subscription1 #e a year4 ,sent by mail1 postage prepaid1 to subscribers in any part of the ,united ,states or ,canada4 ,six dollars a year1 sent1 prepaid1 to any foreign country4 ,all the back numbers of ,the ,supplement1 from the commencement1 ,january #a1 #ahgf1 can be had4 ,price1 #aj cents each4 ,all the back volumes of ,the ,supplement can likewise be supplied4 ,two volumes are issued yearly4 ,price of each volume1 #b4ej stitched in paper1 or #c4ej bound in stiff covers4 ,,combined ,,rates4--,one copy of ,,scientific ,,american and one copy of ,,scientific ,,american ,,supplement1 one year1 postpaid1 #g4jj4 ,a liberal discount to booksellers1 news agents1 and canvassers4 ,,munn ,,co41 #cfa ,,broadway1 ,,new ,,york1 ,n4,y4 99 99 99 99 99 ,a ,new ,catalogue of ,valuable ,papers ,contained in ,,scientific ,,american ,,supplement during the past ten years1 sent free of charge to any address4 ,,munn ,,co41 #cfa ,broadway1 ,new ,york4 99 99 99 99 99 ,,useful ,,engineering ,,books ,manufacturers1 ,agriculturists1 ,chemists1 ,engineers1 ,mechanics1 ,builders1 men of leisure1 and professional men1 of all classes1 need good books in the line of their respective callings4 ,our post office department permits the transmission of books through the mails at very small cost4 ,a comprehensive catalogue of useful books by different authors1 on more than fifty different subjects1 has recently been published1 for free circulation1 at the office of this paper4 ,subjects classified with names of author4 ,persons desiring a copy have only to ask for it1 and it will be mailed to them4 ,address1 ,,munn ,,co41 #cfa ,broadway1 ,new ,york4 99 99 99 99 99 ,,patents4 ,in connection with the ,,scientific ,,american1 ,messrs4 ,,munn ,,co4 are solicitors of ,american and ,foreign ,patents1 have had #db years' experience1 and now have the largest establishment in the world4 ,patents are obtained on the best terms4 ,a special notice is made in the ,,scientific ,,american of all inventions patented through this ,agency1 with the name and residence of the ,patentee4 ,by the immense circulation thus given1 public attention is directed to the merits of the new patent1 and sales or introduction often easily effected4 ,any person who has made a new discovery or invention can ascertain1 free of charge1 whether a patent can probably be obtained1 by writing to ,,munn ,,co4 ,we also send free our ,hand ,book about the ,patent ,laws1 ,patents1 ,caveats1 ,trade ,marks1 their costs1 and how procured4 ,address ,,munn ,,co41 #cfa ,,broadway1 ,,new ,,york4 ,,branch ,,office1 #fbb ,,and #fbd ,f ,,st41 ,,washington1 ,d4,c4 99 99 99 99 99 ,,transcriber',s ,,notes #a4 ,simple and obvious typographical errors have been corrected4 #b4 ,in the article ,manufacture of ,photosensitive ,plates1 the original text referred to room ,u twice4 ,the first instance has been changed to room ,t4 #c4 ,in the article ,an ,improved ,screw ,propeller1 the text refers to the propeller in figure ,a as being four bladed and also two bladed4 ,it is clearly two bladed and the reference to it being four-bladed has been corrected4