,illustration ,,scientific ,,american ,,supplement ,,no4 #eie ,,new ,,york1 ,,may #bh1 #ahhg4 ,scientific ,american ,supplement4 ,vol4 ,,xxiii1 ,no4 #eie4 ,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 ,i4 ,,botany4--,the ,relation of ,tabasheer to ,mineral ,substances4--,the composition of this curious secretion of the bamboo4--,analyses and properties of the material1 according to various observers4--,its appearance under the microscope4 #a illustration4 ,,ii4 ,,chemistry4--,apparatus for ,drying ,flour4--,an apparatus for determining the moisture in flour4 #a illustration4 ,,iii4 ,,electricity4--,automatic ,commutator for ,incandescent ,lamps4--,an apparatus for lighting automatically a new lamp to replace one that has failed4 #a illustration4 ,definitions and ,designations in ,electro-,technics4--,mr4 ,jamieson's proposed code of electric symbols--literal and graphic4 #d illustrations4 ,,iv4 ,,engineering4--,new ,dredging ,machinery4--,the dredger ,ajax1 recently built in ,california4--,its dimensions and capacity4 #a illustration4 ,reservoir ,dams4--,by ,,david ,,gravell4--,the engineering details of dams4--,typical masonry and earthwork dams of the world4 #bc illustrations4 ,the ,flexible ,girder ,tramway4--,a new type of suspended railway--a modification of the wire tramway system4 #ba illustrations4 ,v4 ,,hygiene4--,climate in its ,relation to ,health4--,by ,g4,v4 ,,poore1 ,m4,d4--,the third lecture of this series4--,consideration of the floating matter of the air and diseases caused thereby4--,causation of hay fever4 ,,vi4 ,,mathematics4--,radii of ,curvature ,geometrically ,determined4--,by ,prof4 ,c4,w4 ,,maccord1 ,sc4,d4--,no4 ,,vii4 ,path of a point on a connecting rod4 #c illustrations4 ,,vii4 ,,microscopy4--,improved ,microscopical ,settling ,tube4--,by ,f4 ,,vanderpoel4--,new tubes for use in urinary analysis4 #d illustrations4 ,,viii4 ,,miscellaneous4--,apparatus for ,manufacturing ,bouquets4--,an ingenious machine for facilitating the construction of bouquets4 #a illustration4 ,bozerian's ,refrigerant ,punkas4--,a fan worked by the feet1 a substitute for the ,indian punka4 #b illustrations4 ,how to ,make a ,kite without a ,tail4--,an improved form of kite described and illustrated4 #a illustration4 ,punkas4--,by ,j4 ,,wallace1 ,c4,e4--,the mechanics of punkas2 experiments on their rate of swing4 ,the ,edible ,earth of ,java4--,an account of this curious substance1 its taste and appearance4 ,,ix4 ,,naval ,,engineering4--,another ,remarkable ,torpedo ,boat4--,over twenty-eight miles an hour4--,full particulars of the trial of one of the new ,italian torpedo boats1 built by ,yarrow ,co4 ,copeman ,pinhey's ,life ,rafts4--,a new life raft for use on steamers1 folding into deck settees4 #c illustrations4 ,x4 ,,physics4--,sunlight ,colors--,by ,capt4 ,w4 ,,de ,w4 ,,abney4--,a valuable lecture on the cause of the colors of the sun1 and their relative intensities4 #c illustrations4 ,the ,wave ,theory of ,sound ,considered4--,by ,,henry ,a4 ,,mott1 ,ph4,d41 ,,ll4,d4--,arguments against the generally accepted theory of sound4 99 99 99 99 99 ,,copeman ,,pinhey',s ,,life ,,rafts4 ,the experiments with life saving appliances which ,mr4 ,copeman brought before the delegates of the ,colonial ,conference1 on the #acth ,april1 at the ,westminster ,aquarium1 had a particular interest1 due to the late and lamentable accident which befell the ,newhaven-,dieppe passenger steamer ,victoria4 ,in many cases of this nature1 loss of life must rather be attributed to panic than to a want of life saving appliances2 but1 as a general rule1 an abundant supply of such apparatus will tend to give passengers confidence1 and prevent the outbreak of such discreditable scenes on the part of passengers as took place on the ,victoria4 ,illustration3 ,,fig4 #a4--;,,copeman ,,pinhey',s ,,life ,,rafts4 ,messrs4 ,copeman ,pinhey have1 for some years past1 done good work in this direction1 and at the recent meeting of the ,institution of ,naval ,architects1 ,mr4 ,copeman showed several models of the latest types of their life saving apparatus1 both for use on torpedo boats and passenger steamers4 ,our illustration 7,fig4 #a7 represents the kind of rafts supplied to her ,majesty's troop ships1 while ,figs4 #b and #c show deck seats convertible into rafts1 which are intended for ordinary passenger steamers4 ,the raft shown in ,fig4 #a consists of two pontoons1 joined by strong cross beams1 and fitted with mast1 sail1 and oars4 ,when not in use1 the pontoons form deck seats1 covered by a wooden grating1 which in our illustration forms the middle part of the raft4 ,each pontoon has a compartment for storing provisions1 and when rigged as a raft1 there is a railing to prevent persons being washed overboard4 ,illustration3 ,,fig4 #b4 ,illustration3 ,,fig4 #c4 ,the seat life buoy1 shown in ,fig4 #b1 serves as an ordinary deck seat1 being about #h ft4 long1 and it consists of two portions1 hinged at the back4 ,when required for use as a life buoy1 it is simply thrown forward1 the seat being at the same time lifted upward1 so that the top rail of the back engages with the two clips1 shown at either end of the seat1 and the whole structure then forms a rigid raft1 as will be seen from ,fig4 #c4 ,several other appliances were shown at the ,westminster ,aquarium on ,april #ac1 but the two rafts we have selected for illustration will give a sufficiently correct idea of the general principles upon which the apparatus is based4--,industries4 99 99 99 99 99 ,,another ,,remarkable ,,torpedo ,,boat--,,over ,,twenty-,,eight ,,miles ,,an ,,hour4 ,in a recent impression we gave some particulars of the trial trip of a boat built for the ,italian government by ,messrs4 ,yarrow ,co41 which attained the highest speed known1 namely1 as nearly as possible1 #bh miles an hour4 ,on the #adth ,april the sister boat made her trial trip in the ,lower ,hope1 beating all previous performances1 and attaining a mean speed of #be4aja knots1 or over #bh miles an hour4 ,the quickest run made with the tide was at the rate of #bg4bgb knots1 or #ca4dd miles per hour1 past the shore4 ,this is a wonderful performance4 ,in the following table we give the precise results3 ---------------------------------------- --------- ,second ,boiler4,receiver4,vacuum4,revs4 ,speed4 ,means4 ,means4 ---------------------------------------- --------- per ,knots ,knots ,knots lb4 lb4 in4 min4per hr4per hr4per hr4 ---------------------------------------- --------- #a #acj #cb #bh #cgc #bb4fda #bd4ief #b #acj #cb #bh #cgb4g #bg4bgb #be4jbh #bd4iib #c #acj #cb #bh #cgb #bb4ghd #be4jbh #be4jbh #d #acj #cb #bh #cgg #bg4bgb #be4bdh #be4ach #e #acj #cb #bh #cge #bc4bbe #be4bdh #be4bdh #f #acj #cb #bh #cgg #bg4bgb ---------------------------------------- --------------- ,means #acj #cb #bh #cgd4e #be4aja ---------------------------------------- --------------- ,the boat is #adj ft4 long1 and fitted with twin screws driven by compound engines1 one pair to each propeller4 ,these engines are of the usual type1 constructed by ,messrs4 ,yarrow4 ,each has two cylinders with cranks at #ij4 ,the framing1 and1 indeed1 every portion not of phosphor-bronze or gun metal1 is of steel1 extraordinary precautions being taken to secure lightness4 ,thus the connecting rods have holes drilled through them from end to end4 ,the low pressure cylinders are fitted with slide valves4 ,the high pressure valves are of the piston type1 all being worked by the ordinary link motion and eccentrics4 ,the engine room is not far from the mid length of the boat1 and one boiler is placed ahead and the other astern of it4 ,each boiler is so arranged that it will supply either engine or both at pleasure4 ,the boat has therefore two funnels1 one forward and the other aft1 and air is supplied to the furnaces by two fans1 one fixed on the forward and the other on the aft bulkhead of the engine room4 ,the fan engines have cylinders #e in4 diameter and #c in4 stroke1 and make about #a1ajj revolutions per minute when at full speed1 causing a plenum in the stokeholes of about #f in4 water pressure4 ,double steam steering gear is fitted1 for the forward and aft rudder respectively1 and safety from foundering is provided to an unusual degree by the subdivision of the hull into numerous compartments1 each of which is fitted with a huge ejector1 capable of throwing overboard a great body of water4 ,a body of water equal to the whole displacement of the boat can be discharged in less than seven minutes4 ,there is also a centrifugal pump provided1 which can draw from any compartment4 ,the circulating pump is not available1 because it has virtually no existence1 a very small pump on the same shaft as the centrifugal being used merely to drain the condensers4 ,these last are of copper1 cylindrical1 and fitted with pipes through which a tremendous current of water is set up by the passage of the boat through the sea4 ,thus the space and weight due to a circulating pump is saved and complication avoided4 ,the air and feed pumps are combined in one casting let into the engine room floor1 quite out of the way1 and worked by a crank pin in a small disk on the forward end of the propeller shaft4 ,this is an admirable arrangement1 and works to perfection4 ,the armament of the boat consists of two torpedo tubes in her bows1 and a second pair set at a small angle to each--,yarrow's patent--carried aft on a turntable for broadside firing4 ,there are also two quick firing #c lb4 guns on her deck4 ,the conning tower forward is rifle proof1 and beneath it and further forward is fixed the steering engine1 and a compressing engine1 by which air is compressed for starting the torpedoes overboard and for charging their reservoirs4 ,a small dynamo and engine are also provided for working a search light1 if necessary4 ,the accommodation provided for the officers and crew is far in advance of anything hitherto found on board a torpedo boat4 ,the weather on the morning of ,thursday1 ,april #ad1 was anything rather than that which would be selected for a trial1 or indeed any1 trip on the ,thames4 ,at #aa ,a4,m41 the hour at which the boat was to leave ,messrs4 ,yarrow's yard1 ,isle of ,dogs1 the wind was blowing in heavy squalls from the northeast1 accompanied by showers of snow and hail4 ,the ,italian government was represented by ,count ,gandiani and several officers and engineers4 ,in all there were about thirty-three persons on board4 ,the displacement of the vessel was as nearly as might be #ig tons4 ,a start was made down the river at #aa3ae ,a4,m41 the engines making about #ahj revolutions per minute1 and the boat running at some #aa or #ab knots4 ,during this time the stokehole hatches were open1 but the fans were kept running at slow speed to maintain a moderate draught4 ,the fuel used throughout the trip was briquettes made of the best ,welsh anthracite worked up with a little tar4 ,the briquettes were broken up to convenient sizes before being put in the bunkers4 ,this fuel is not of so high evaporative efficiency as ,nixon's navigation coal1 but it is more suitable for torpedo boat work1 because it gives out ,very little dust1 while the coal in closed stokeholes half smothers the firemen4 ,watering only partially mitigates the evil4 ,besides this1 the patent fuel does not clinker the tube ends--a matter of vital importance4 ,during the run down to ,gravesend1 the small quantity of smoke given out was borne down and away from the tops of the funnels by the fierce head wind1 and now and then a heavy spray broke on the bows1 wetting everything forward4 ,in the engine room preparations were made for taking indicator diagrams4 ,no attempt was made to drive the boat fast1 because high speeds are prohibited by the river authorities on account of the heavy swell set up4 ,the measured mile on the ,lower ,hope is on the southern bank of the river1 about three miles below ,gravesend4 ,just as the boat passed the town1 in the midst of a heavy rain squall1 the stokehole hatches in the deck were shut1 and the dull humming roar of the fans showed that the fires were being got up4 ,the smoke no longer rose leisurely from the funnels4 ,it came up now with a rush and violence which showed the powerful agency at work below4 ,a rapid vibrating motion beneath the feet was the first evidence that the engines were away full speed4 ,as the boat gathered way she seemed to settle down to her work1 and the vibration almost ceased4 ,the measured mile was soon reached1 and then in the teeth of the northeaster she tore through the water4 ,the tide and wind were both against her4 ,had the tide and wind been opposed1 there would have been a heavy sea on4 ,as it was1 there was quite enough2 the water1 breaking on her port bow1 came on board in sheets1 sparkling in the sun1 which1 the rain squall having passed1 shone out for the moment4 ,as the wind was blowing at least thirty miles an hour1 and the boat was going at some twenty-six miles an hour against it1 the result was a moderate hurricane on board4 ,it was next to impossible to stand up against the fury of the blast without holding on4 ,the mile was traversed in less than #b minutes1 however2 but the boat had to continue her course down the river for nearly another mile to avoid some barges which lay in the way1 and prevented her from turning4 ,then the helm was put over1 and she came round4 ,there was no slacking of the engines1 and astern of her the water leaped from her rudder in a great upheaved1 foaming mass1 some #g ft4 or #h ft4 high4 ,brought round1 she once more lay her course4 ,this time the wind was on her starboard quarter1 or still more nearly aft4 ,the boat went literally as fast as the wind1 and on deck it was nearly calm4 ,the light smoke from the funnels1 no longer beaten down by wind1 leaped up high into the air4 ,looking over the side1 it was difficult to imagine that the boat was passing through water at all4 ,the enormous velocity gave the surface of the river the appearance of a sheet of steel for #a ft4 or more outside the boat4 ,standing right aft1 the sight was yet more remarkable4 ,although two #f ft4 screws were revolving at nearly #djj revolutions per minute almost under foot1 not a bubble of air came up to break the surface4 ,there was no wave in her wake2 about #gj ft4 behind her rose a gentle swelling hill4 ,her wake was a broad smooth brown path1 cut right through the rough surface of the river4 ,on each side of this path rose and broke the angry little seas lashed up by the scourging wind4 ,along the very center of the brown track ran a thin ridge of sparkling foam1 some #b ft4 high and some #bj ft4 long1 caused by the rudder being dragged through the water4 ,there was scarcely any vibration4 ,the noise was not excessive4 ,a rapid whirr due to the engines1 and a rythmical clatter due to the relief valve on one of the port engine cylinders not being screwed down hard enough1 and therefore lifting a little in its seat at each stroke1 made the most of it4 ,the most prominent noise perhaps was the hum of the fans4 ,standing forward1 the deck seems to slope away downward aft1 as indeed it does1 for it is to be noted that at these high speeds the forefoot of the boat is always thrown up clean out of the water--and the whole aspect of the boat3 the funnels vomiting thin brown smoke1 and occasionally1 when a fire door is opened1 a lurid pillar of flame for a moment2 the whirr in the engine room2 the dull thunder of the fans1 produce an impression on the mind not easily expressed1 and due in some measure no doubt to the exhilaration caused by the rapid motion through the air4 ,the best way to convey what we mean is to say that the whole craft seems to be alive1 and a perfect demon of energy and strength4 ,many persons hold that a torpedo boat is likely to be more useful in terrifying an enemy than in doing him real harm1 and we can safely say that the captain of an ironclad who saw half a dozen of these vessels bearing down on him1 and did not wish himself well out of a scrape1 has more nerve than most men4 ,the second mile was run in far less time than that in which what we have written concerning it can be read1 and then the boat turned again1 and once more the head wind with all its discomforts was encountered4 ,events repeated themselves1 and so at last the sixth trip was completed1 and the boat proceeded at a leisurely pace back again to ,poplar4 ,mr4 ,crohn1 representing ,messrs4 ,yarrow on board1 and all concerned1 might well feel satisfied4 ,we had traveled at a greater speed than had ever before been reached by anything that floats1 and there was no hitch or impediment or trouble of any kind4 ,the ,italian government may be congratulated on possessing the two fastest and most powerful torpedo boats in the world4 ,we believe1 however1 that ,messrs4 ,yarrow are quite confident that1 with twin screw triple expansion engines1 they can attain a speed of #bf knots an hour1 and we have no reason to doubt this4--,the ,engineer4 99 99 99 99 99 ,,reservoir ,,dams4 ,footnote3 ,paper1 with slight abbreviation1 read by ,mr4 ,david ,gravell1 ,assoc4 ,m4 ,inst4 ,c4,e41 before the ,society of ,civil and ,mechanical ,engineers4 ,the paper brings together in a convenient form the sections and salient facts concerning many dams4 ,it was illustrated by numerous diagrams1 from which our engravings have been prepared4--,the ,engineer4 ,by ,,david ,,gravell4 ,the construction of dams1 in some form or other1 may probably rank among the very earliest of engineering works4 ,works of this character are not infrequently referred to in the accounts of the earliest historians2 but it is to be feared that they are not always perfectly trustworthy4 ,the subscribers to the ,mudie of the period had to be considered1 and their taste for the marvelous was probably not much inferior to that of our own day4 ,when1 therefore1 ,herodotus describes the reservoir of ,moeris as formed for the control of the river floods of ,nile-nourished ,egypt1 and of another constructed by ,nebuchadnezzar at ,sippara1 of #adj miles in circumference1 we must make allowances4 ,but there is no question as to the existence in the ,east at the present day1 and especially in ,india and ,ceylon1 of the remains of what may correctly be termed stupendous works2 and the date of the construction of which1 as regards ,india1 is in many cases prehistoric4 ,in ,spain also the ,moors1 whose occupation of the peninsula terminated in the thirteenth century1 have left reservoir dams of great magnitude1 situated mostly in the south-eastern provinces of ,murcia and ,alicante1 and many of which are still serviceable4 ,in ,india and ,ceylon the greater number of the ancient dams or bunds are now in ruins1 and this can occasion but little surprise1 considering the meteorological condition of these countries4 ,in ,ceylon1 for instance1 the whole rainfall of the year occurs within a period of six to eight weeks1 and often amounts to as much as #ab in4 in the twenty-four hours1 and has been known1 comparatively recently1 to reach nearly #ai in41 the latter an amount only #b in4 or #c in4 less than the average rainfall of ,lincolnshire for the whole year4 ,in ,london it is only #be in4 and in the wettest district in ,great ,britain1 viz41 ,cumberland1 averages not more than #gj in4 per annum4 ,the rainfall in ,bombay is from #hj in4 to #ajj in4 per annum1 and throughout ,india may be taken as from #ej in4 to #acj in41 varying1 as is the general rule1 in direct ratio with the altitude1 and limited to a few weeks in the year4 ,notwithstanding this1 there still exist in the ,madras ,presidency a not inconsiderable number of ancient bunds which serve their intended purpose at the present day as well as ever4 ,slight mistakes did occasionally occur1 as they ever will till no more dams are wanted1 as is proved by the remains of some works in ,ceylon1 where the failure was evidently due to error1 possibly due to the instruments being out of adjustment1 as their base is at a higher level than the bed of the stream at the point where water from the latter was to be diverted to afford the supply4 ,among the most remarkable of these ancient works is the ,horra-,bera tank1 the bund of which is between three and four miles in length and from #ej to #gj ft4 in height1 and although now in ruins would formerly impound a reservoir lake of from eight to ten miles long and three to four miles broad4 ,there is also the ,kala-,weva tank1 with a bund of twelve miles in length1 which would1 if perfect1 create a lake of forty miles in circumference4 ,both of these ruined works are situated in ,ceylon4 ,the third embankment of a similar character is that of the ,cummum tank1 situated in the ,madras ,presidency1 and which1 though ranking among the earliest works of ,hindoo history1 is still in such a condition as to fulfill its original intention4 ,the area of the reservoir is about fifteen square miles1 the dam about #ajb ft4 high1 with a breadth at the crest of #gf ft41 and of the section shown in the diagram4 ,the by-wash is cut in the solid rock altogether clear of the dam2 the outlet culverts1 however1 are carried under the bank4 ,we will now consider generally the methods employed in determining the site1 dimensions1 and methods of construction of reservoir dams adapted to the varying circumstances and requirements of modern times1 with a few references to some of the more important works constructed or in progress1 which it will be endeavored to make as concise and burdened with as few enumerations of dimensions as possible4 ,the amount of the supply of water required1 and the purposes to which it is to be applied1 whether for household1 manufacturing1 or irrigation uses1 are among the first considerations affecting the choice of the site of the reservoir1 and is governed by the amount of rainfall available1 after deducting for evaporation and absorption1 and the nature of the surface soil and vegetation4 ,the next important point is to determine the position of the dam1 having regard to the suitability of the ground for affording a good foundation and the impoundment of the requisite body of water with the least outlay on embankment works4 ,it has been suggested that the floods of the valley of the ,thames might be controlled by a system of storage reservoirs1 and notice was especially drawn to this in consequence of the heavy floods of the winter of #ahge4 ,from evidence given before the ,royal ,commission on ,water ,supply1 previous to that date it was stated that a rainfall of #a in4 over the ,thames basin above ,kingston would give1 omitting evaporation and absorption1 a volume of #ec1cge1jjj1jjj gallons4 ,to prevent floods1 a rainfall of at least #c in4 would have to be provided against1 which would mean the construction of reservoirs of a storage capacity of say #afj1jjj1jjj1jjj gallons4 ,mr4 ,bailey ,denton1 in his evidence before that commission1 estimated that reservoirs to store less than one tenth that quantity would cost #a1cfj1jjj1 and therefore a #c in4 storage as above would require an outlay of1 say1 #ae1jjj1jjj sterling2 and it will be seen that #c in4 is by no means too great a rainfall to allow for1 as in ,july of #ahge1 according to ,mr4 ,symons1 at ,cirencester1 #c4aa in4 fell within twenty-four hours4 ,supposing serious attention were to be given to such a scheme1 there would1 without doubt1 be very great difficulty in finding suitable situations1 from an engineering and land owner's point of view1 for the requisite dams and reservoir areas4 ,in ,great ,britain and many ,european countries rain gauges have been established at a greater or less number of stations for many years past1 and data thereby afforded for estimating approximately the rainfall of any given district or catchment basin4 ,the term watershed is one which it appears to me is frequently misapplied2 as ,i understand it1 watershed is equivalent to what in ,america is termed the divide1 and means the boundary of the catchment area or basin of any given stream1 although ,i believe it is frequently made use of as meaning the catchment area itself4 ,when saying that the rain gauges already established in most of the older civilized countries afford data for an approximate estimate only1 it is meant that an increase in the number of points at which observations are made is necessary1 previous to the design of a reservoir dam on the catchment area above1 the waters of which are proposed to be impounded1 and should be continuous for a series of five or six years1 and these must be compared with the observations made with the old established rain gauges of the adjacent district1 say for a period of twenty years previously1 and modified accordingly4 ,this is absolutely necessary before an accurate estimate of the average and maximum and minimum rainfall can be arrived at1 as the rainfall of each square mile of gathering ground may vary the amount being affected by the altitude and the aspect as regards the rainy quarter4 ,but this information will be of but little service to the engineer without an investigation of the loss due to evaporation and absorption1 varying with the season of the year and the more or less degree of saturation of the soil2 the amount of absorption depending upon the character of the ground1 dip of strata1 etc41 the hydrographic area being1 as a rule1 by no means equal to the topographic area of a given basin4 ,from this cursory view of the preliminary investigations necessary can be realized what difficulties must attend the design of dams for reservoirs in newly settled or uncivilized countries1 where there are no data of this nature to go on1 and where if maps exist they are probably of the roughest description and uncontoured2 so that before any project can be even discussed seriously special surveys have to be made1 the results of which may only go to prove the unsuitability of the site under consideration as regards area1 etc4 ,the loss due to evaporation1 according to ,mr4 ,hawksley1 in this country amounts to a mean of about #ae in42 this and the absorption must vary with the geological conditions1 and therefore to arrive at a satisfactory conclusion regarding the amount of rainfall actually available for storage1 careful gaugings have to be made of the stream affected1 and these should extend over a lengthened period1 and be compounded with the rainfall4 ,a certain loss of water1 in times of excessive floods1 must1 in designing a dam1 be ever expected1 and under favorable conditions may be estimated at #aj per cent4 of the total amount impounded4 ,as regards the choice of position for the dam of a reservoir1 supposing that it is intended to impound the water by throwing an obstruction across a valley1 it may be premised that to impound the largest quantity of water with the minimum outlay1 the most favorable conditions are present where a more or less broad valley flanked by steep hills suddenly narrows at its lower end1 forming a gorge which can be obstructed by a comparatively short dam4 ,the accompanying condition is that the nature of the soil1 i4e41 the character1 strata1 and lie of the rock1 clay1 etc41 as the case may be1 is favorable to assuring a good foundation4 ,in ,great ,britain1 as a rule1 dams for reservoirs have been constructed of earthwork with a puddle core1 deemed by the majority of ,english engineers as more suitable for this purpose than masonry4 ,earthwork1 in some instances combined with masonry1 was also a form usual in the ancient works of the ,east1 already referred to2 but it would appear from the experience of recent years that masonry dams are likely to become as common as those of earthwork1 especially in districts favorable to the construction of the former1 where the natural ground is of a rocky character1 and good stone easily obtained4 ,as to the stability of structures of masonry for this purpose1 as compared with earthwork1 experience would seem to leave the question an open one4 ,either method is liable to failure1 and there certainly are as many cases on record of the destruction of masonry dams as there are of those constructed of earthwork1 as instanced in ,algeria within the past few years4 ,as regards masonry dams1 the question of success does not seem so much to depend upon their design1 as far as the mere determination of the suitable profile or cross section is concerned1 as that has been very exhaustively investigated1 and fairly agreed upon1 from a mathematical point of view1 but to be principally due to the correctness of the estimate of the floods to be dealt with1 and a sufficient provision of by-wash allowed for the most extreme cases2 and1 lastly1 perhaps the most important of all1 the securing a thoroughly good foundation1 and a careful execution of the work throughout4 ,these remarks equally apply to earthwork dams1 as regards sufficient provision of by-wash1 careful execution of work1 and security of foundation1 but their area of cross section1 supposing them to be water-tight1 on account of the flatness of their slopes and consequent breadth of base1 is1 of course1 far in excess of that merely required for stability2 but in these latter1 the method adopted for the water supply discharge is of the very greatest importance1 and will be again referred to4 ,before commencing the excavation for the foundations of a dam1 it is most essential that the character of the soil or rock should be examined carefully1 by sinking a succession of small shafts1 not mere borings1 along the site1 so that the depth to which the trench will have to be carried1 and the amount of ground water likely to be encountered1 can be reliably ascertained1 as this portion of the work cannot be otherwise estimated1 and as it may bear a very large proportion of the total expense of construction1 and in certain cases may demonstrate that the site is altogether unsuitable for the proposed purpose4 ,the depth to which puddle trenches have been carried1 for the purpose of penetrating water-bearing strata1 and reaching impenetrable ground1 in some cases1 has been as much as #afj ft4 below the natural surface of the ground1 and the expense of timbering1 pumping1 and excavation in such an instance can be easily imagined4 ,this may be realized by referring to ,fig4 #d1 giving a cross-section of the ,yarrow dam1 in which the bottom of the trench is there only #he ft4 below the ground surface4 ,in the ,dale ,dyke dam1 ,fig4 #b1 the bottom of the trench was about #ej ft4 below the ground surface4 ,there is one other point which should be mentioned in connection with the form of the base of the puddle trench--that instead of cutting the bottom of the trench at the sides of the valley in steps1 it should be merely sloped1 so that the puddle1 in setting1 tends to slide down each inclined plane toward the bottom of valley1 thereby becoming further compressed2 whereas1 should the natural ground be cut in steps1 the puddle in setting tends to bulge at the side of each riser1 as it may be termed1 and so cause fissures4 ,it will be noticed that the slopes of these earthwork dams vary from #g to #a to #b to #a4 ,the depths to which some puddle trenches are carried has been objected to by some engineers1 and among them ,sir ,robert ,rawlinson1 as excessive and unnecessary1 and1 in the opinion of the latter1 the same end might be obtained by going down to a depth say of #cj ft4 only1 and putting in a thick bed of concrete1 and also carrying up the concrete at the back of the puddle trench1 with a well for collecting water1 and a pipe leading the same off through the back of the dam to the down stream side4 ,an arrangement of this kind is shown in the ,yarrow dam1 ,fig4 #d4 ,the thickness of the puddle wall varies considerably in the different examples given in the diagrams before you1 a fair average being the ,row bank of the ,paisley ,water ,works1 ,fig4 #f2 and although in instances of dams made early in the century1 such as the ,glencorse dam--,fig4 #e--of the ,edinburgh ,water ,works1 the puddle was of very considerable thickness1 and it would appear rightly so4 ,this practice does not seem to have been followed in many cases1 as1 for instance1 again referring to the ,dale ,dyke dam1 ,fig4 #b1 where the thickness of the top was only #d ft41 with a batter of #a in #af downward1 giving a thickness of #af ft4 at the base4 ,for a dam #ie ft4 in height this is very light1 compared with that of the ,vehui dam at ,bombay1 of which the engineer was ,mr4 ,conybeare--,fig4 #g--where the puddle wall is #aj ft4 wide at the top1 with a batter downward of #a in #h1 the ,bann reservoir--,fig4 #h--of ,mr4 ,bateman's design1 where the puddle is #h ft4 broad at the top1 and other instances4 ,the same dimension was adopted for the puddle wall of the ,harelaw reservoir1 at ,paisley1 by ,mr4 ,alexander ,leslie1 an engineer of considerable experience in dam construction4 ,there appears to be a question as to what the composition of puddle should be1 some advocating a considerable admixture of gravel with clay4 ,there is no doubt that clay intended for puddle should be exposed to the weather for as long previous to use as possible1 and subject to the action of the air at any rate1 of sunshine if there be any1 or of frost4 ,when deposited in the trench1 it should be spread in layers of not more than #f in4 in thickness1 cut transversely in both directions1 thoroughly watered1 and worked by stamping4 ,the position of the puddle wall is1 as a rule1 in the center of the bank and vertical2 but laying a thickness of puddle upon the inner or up stream slope1 say #c ft4 thick1 protected by a layer of gravel and pitching1 has been advocated as preventing any portion of the dam from becoming saturated4 ,there are1 however1 evident objections to this method1 as the puddle being comparatively unprotected would be more liable to damage by vermin1 such as water rats1 etc42 and in case of the earthwork dam at the back settling1 as would certainly be the case1 unless its construction extended over a very lengthened period1 the puddle would be almost certain to become fissured and leaky2 in addition1 the comparative amounts of puddle used in this manner1 as compared with the vertical wall1 would be so much increased4 ,with the puddle wall in the position usually adopted1 unequal settlement of the bank on either side is less liable to affect the puddle1 being vertical4 ,it would be interesting to refer to the embankment of the ,bann1 or ,lough ,island ,reavy reservoir1 ,fig4 #h1 designed by ,mr4 ,bateman1 now nearly fifty years ago1 where a layer of peat was adopted both on the slope1 #ae in4 thick1 and in front or on the up stream side of the puddle wall1 #c ft4 thick4 ,the object was1 that should the puddle become fissured and leaky1 the draught so created would carry with it particles of peat1 which would choke up the cracks and so reduce the leakage that the alluvial matter would gradually settle over it and close it up4 ,on the same diagram will be noticed curved lines1 which are intended to delineate the way in which the earthwork of the embankment was made up4 ,the layers were #c ft4 in thickness1 laid in the curved layers as indicated4 ,it is a moot question whether1 in making an earthwork embankment1 dependence1 as far as stanchness is concerned1 should be placed upon the puddle wall alone or upon the embankments on either side1 and especially upon the up-stream side in addition4 ,supposing the former idea prevails1 then it can be of little moment as to how or of what material the bank on either side is made up--whether of earth or stone--placed in thin layers or tipped in banks of #c ft4 or #d ft4 high2 but the opinion of the majority of engineers seems to be in favor of making the banks act not merely as buttresses to the puddle wall1 and throwing the whole onus1 as it may be termed1 of stanchness upon that1 but also sharing the responsibility and lessening the chances of rupture thereby4 ,but to insure this1 the material must be of the very best description for the purpose4 ,stones1 if allowed at all--and in the author's opinion they should not be--should be small1 few1 and far between4 ,let those that are sifted out be thrown into the tail of the down stream slope4 ,they will do no harm there1 but the layers of earth must not approach #c ft4 in thickness nor #a ft4--the maximum should be six in41 and this applies also to the puddle4 ,let the soil be brought on by say one-horse carts1 spread in six inch layers1 and well watered4 ,the traffic of the carts will consolidate it1 and in places where carts cannot traverse it should be punned4 ,in the ,parvy reservoir dam a roller was employed for this purpose4 ,it comprised a small lorry body holding about a yard and a half of stone1 with two axles1 on each of which was keyed a row of five or six wheels4 ,at the ,oued ,meurad dam1 in ,algeria1 #ie ft4 high1 constructed about #bc years ago1 the earthwork layers were deposited normal to the outer slope1 and as the bank was carried up the water was admitted and allowed to rise to near the temporary crest1 and as soon as the bank had settled1 the earthwork continued another grade1 and the same process repeated4 ,it was the practice until comparatively recently to make the discharge outlet by laying pipes in a trench under the dam1 generally at the lowest point in the valley1 or constructing a culvert in the same position and carrying the pipes through this1 and in the earlier works the valves or sluices regulating the outflow were placed at the tail of the down stream bank1 the pipes under the bank being consequently at all times subject to the pressure of the full head of the water in the reservoir4 ,an instance of the first mentioned method is afforded by the ,dale ,dyke reservoir1 ,fig4 #b1 where two lines of pipes of #ah in4 diameter were laid in a trench excavated in the rock and resting upon a bed of puddle #ab in4 in thickness1 and surrounded by puddle2 the pipes were of cast iron1 of the spigot and faucet type1 probably yarned and leaded at the joints as usual1 and the sluice valves were situated at the outer end of the pipes4 ,as the failure of this embankment was1 as we all know1 productive of such terrible consequences1 it may be of interest to enter a little more fully into the details of its construction4 ,it was situated at ,bradfield1 six or seven miles from ,sheffield1 and at several hundred feet higher level4 ,its construction was commenced in #aheh1 the puddle trench was probably taken down to a depth of #dj ft4 to #ej ft41 a considerable amount of water being encountered4 ,this trench was #ae ft4 to #bj ft4 broad at the top1 and of course had to be crossed by the before mentioned line of pipes2 and although the trench was filled with puddle1 and the gullet cut in the rock already mentioned for carrying the pipes under the site of the dam was padded with a layer of #ab in4 of puddle1 we can imagine that the effect of the weight of the puddle wall and bank upon this line of pipes would be very different at the point where they crossed the puddle trench to what it would be where they were laid in the rock gullet and partially protected from pressure by the sides of the latter4 ,at the trench crossing there would be a bed of puddle #ej ft4 in thickness beneath the pipe1 in the gullet a bed of #a ft4 in thickness4 ,so much as regards the laying of the pipes4 ,the embankment had scarcely been completed when1 on ,march #aa1 #ahfd1 a storm of rain came on and nearly filled it up to the by-wash1 when the bank began slowly to subside4 ,the engineer was on the crest at the very time1 and remained until the water was running over his boots2 he then rushed down the other slope and was snatched out of the way as the bank burst1 and the whole body of water1 about #bej1jjj1jjj gallons1 rushed out through the trench1 carrying with it in the course of about twenty minutes #ib1jjj cubic yards1 or say one fourth of the total mass of earthwork1 causing the death of #bej human beings1 not to mention cattle1 and destruction of factories1 dwellings1 and bridges1 denuding the rock of its surface soil1 and1 as it were1 obliterating all the landmarks in its course4 ,the greatest depth of the bank from ground level to crest was #ie ft41 the top width #ab ft41 and the slopes1 both on the up stream and down stream sides1 #b to #a1 and the area of the reservoir #gh acres4 ,mr4--now ,sir ,robert--,rawlinson1 together with ,mr4 ,beadmore1 were called in to make a report1 to lay before ,parliament1 upon this disaster2 and having made a careful examination of the ruins1 and taken evidence1 they were of opinion that the mode of laying the pipes1 and in such an unprotected way1 was faulty1 and that subsidence of the pipes probably occurred at the crossing of the puddle trench4 ,a fissure in the puddle was created1 affording a creep for the water1 which1 once set up1 would rapidly increase the breach by scour2 and this event was favored by the manner in which the bank had been constructed and the unsuitability of the material used1 which1 in the words of one engineer1 had more the appearance of a quarry tip than of a bank intended to store water4 ,this opinion of the cause of failure was1 however1 not adopted universally by engineers1 the line of pipes when examined being found to be1 although disjointed1 fairly in line2 and there having occurred a land slip in the immediate neighborhood1 it was suggested that the rupture might be caused by a slip also having taken place here1 especially as the substratum was of flagstone rock tilted at a considerable angle4 ,the formation was millstone grit4 ,this catastrophe induced an examination to be made of other storage reservoir dams in the same district1 and a report on the subject was presented to ,parliament by ,sir ,robert ,rawlinson4 ,illustration3 ,,typical ,,masonry ,,and ,,earthwork ,,dams ,,of ,,the ,,world4 ,the dam of ,stubden reservoir1 of the ,bradford water supply1 also on the millstone grit1 was constructed about #ahei1 and caused considerable anxiety for a length of time1 as leakage occurred in the culvert carrying the pipes1 under the embankment at a point a short distance on the down stream side of the puddle trench4 ,this was repaired to some extent by lining with cast iron plates2 and an entirely independent outlet was made by driving a curved tunnel into the hill side clear of the ends of the dam and lining it with cast iron plates4 ,in this tunnel was then laid the main of #b ft4 diameter1 and as the original culvert again became leaky1 the water had to be lowered1 the old masonry pulled out1 and the space filled in with puddle4 ,the ,leeming compensation reservoir of the same water supply1 with a dam of #ej ft4 in height1 and culvert outlet1 had to be treated somewhat in the same manner1 as1 although the reservoir had never been filled with water1 in #ahge1 when it was examined previous to filling1 it was found that the culvert was cracked in all directions2 and it was deemed best to fill it up with ,portland cement concrete1 and drive a tunnel outlet through the hill side1 as described in the case of the ,stubden reservoir4 ,the ,leeshaw dam1 which was being constructed at that time upon the same lines1 viz41 with culvert outlet under the dam1 was1 at the advice of ,sir ,robert ,rawlinson1 altered to a side tunnel outlet clear of the dam4 ,some years previous to the failure of the ,dale ,dyke reservoir there occurred1 in #aheb1 a failure of a similar character--though1 as far as the author is aware1 unattended by such disastrous results--at the ,bilberry reservoir at ,holmfirth1 near ,huddersfield1 which had never been filled previous to the day of its failure1 and arose from the dam having sunk1 and being allowed to remain at a level actually below that of the by-wash2 so that when the storm occurred1 the dam was topped and destroyed4 ,an after examination proved that the bank was badly constructed and the foundation imperfect4 ,besides the above instances1 there have been numerous failures within recent times of earthwork dams in ,spain1 the ,united ,states1 ,algeria1 and elsewhere1 such as that which occurred at ,estrecho de ,rientes1 near ,lorca1 in ,murcia1 where a dam #aej ft4 high1 the construction of which for irrigation purposes was commenced in #agee and completed in #aghi1 was filled for the first time in ,february1 #ahjb1 and two months later gave way1 destroying part of the town of ,lorca and devastating a large tract of the most fertile country1 and causing the death of #fjj people4 ,the immediate cause of failure in this case the author has been unable to ascertain4 ,in ,algeria the ,sig and ,tlelat dams were destroyed in #ahfe2 and in the ,united ,states of ,america1 at ,williamsburg1 ,hampshire ,co41 ,massachusetts1 in #ahgd1 an earthwork dam gave way1 by which #aei lives were lost and much damage done to property4 ,in another case1 viz41 that of the ,worcester dam1 in the ,united ,states of ,america--impounding a volume of #ffc1ccj1jjj gallons1 and #da ft4 high1 #ej ft4 broad at the crest1 and formed with a center wall of masonry1 with earthwork on each side--which gave way in #ahge1 four years after its completion2 here1 as in almost all other instances of failure1 the leakage commenced at a point where the pipes traverse the dam4 ,in this case they were carried in a masonry culvert1 and the leak started at about #bj ft4 on the up stream side of the central wall4 ,the opinion of ,mr4 ,mc,alpine as to the cause of failure1 which agrees with that of the most eminent of our own water engineers1 was to the effect that earthen dams rarely fail from any fault in the artificial earthwork1 and seldom from any defect in the natural soil4 ,the latter may leak1 but not so as to endanger the dam4 ,in nine tenths of the cases1 the dam is breached along the line of the water outlet passages4 ,the method of forming the discharge outlet by the construction of a masonry culvert in the open has no doubt many advantages over that of tunnel driving through the hill side clear of the dam1 permitting as it does of an easy inspection and control of the work as it proceeds2 but a slight leakage in the instance of a side tunnel probably means nothing more than the waste of so much water1 whereas in the case of the culvert traversing the site of the bank1 the same amount or less imperils the stability of the bank1 and in ninety-nine cases out of a hundred would1 if not attended to1 sooner or later be the cause of its destruction4 ,i think the majority will therefore agree that the method of discharge outlets under the site of embankments should not be tolerated where it is possible to make an outlet in the flank of the hill1 to one side1 and altogether clear of the dam4 ,at ,fig4 #i is a diagram of the ,roundwood dam of the ,vartry ,water ,works1 supplying ,dublin1 which is a fair specimen of the class of earthwork dam with the outlet pipes carried in a culvert under the embankment1 and which1 perhaps1 is one of the most favorable specimens of this method of construction1 as the inlet valves are on the up stream of the dam1 and consequently when necessary the water can be cut off from the length of pipes traversing the dam4 ,a short description will be given4 ,this dam is #ff ft4 high at the deepest point and #bh ft4 wide at the crest1 having to carry a public road4 ,the slope on the inner face is #c to #a1 and on the outer #b to #a4 ,the by-wash is #f ft4 below the crest1 which is about the average difference4 ,the storage capacity of the reservoir is #b1djj1jjj1jjj gallons1 or sufficient for #bjj days' supply to the city4 ,the puddle wall is #f ft4 wide at the top and #ah ft4 at ground level1 the bottom of the puddle trench about #dj ft4 below the surface of the ground4 ,the culvert was formed by cutting a gullet #ad ft4 wide with nearly vertical sides through the rock1 and covering it with a semicircular arch #d ft4 in thickness4 ,through this tunnel are laid a #cc in4 and #dh in4 main2 the former for the water supply1 and the latter for scouring or for emptying the reservoir on an emergency4 ,there is a plugging of brickwork in cement under the center of the dam in the line of the puddle wall1 and then stop walls built at the end of the plugging1 projecting #be ft4 beyond the sides of the culvert and #h ft4 above1 the space between them being filled up with cement concrete tied into the rock1 and on this the puddle wall rests4 ,this bank1 like almost all others pierced by outlet pipes or culverts1 was not destined to be perfect4 ,in #ahfg1 four years after the completion1 spurts of water showed themselves in the culvert in front of the puddle wall1 which began to settle1 and the water had to be drawn off to admit of repairs4 ,diagram ,no4 #aj shows a structure of a different character to any of these already described4 ,this character of work is adopted on the ,north ,poudre ,irrigation ,canal1 in ,n4,e4 ,colorado4 ,timber is there plentiful1 and a dam of this character can be rapidly constructed1 although probably not very durable1 owing to liability to decay of timber4 ,that represented is about #be ft4 high4 ,the author has now concluded the consideration of earthwork dams1 and proposes making a few remarks upon those of masonry or concrete1 with reference to some of the most important1 as shown on the diagrams4 ,their stability1 unlike those of earthwork1 may be considerably increased where the contour and nature of the ground is favorable by being curved in plan1 convex toward the water1 and with a suitable radius4 ,they are especially suitable for blocking narrow rocky valleys1 and as such situations must1 from the character of the ground1 be liable to sudden and high floods1 great care is necessary to make sufficient provision for overflow4 ,when of masonry1 the stones should be bonded1 not merely as they would be in an ordinary vertical wall1 where the direction of the stress is perpendicular1 but each course should be knit in with that above and below it in a somewhat similar manner to what is termed random work4 ,and lastly1 if hydraulic mortar be used1 a sufficient time should elapse after construction before being subjected to strain1 or in other words1 before water is allowed to rise in the reservoir4 ,for this latter reason1 and also the liability to damage by sudden floods during the progress of the works1 dams of ,portland cement concrete1 on account of their quick consolidation1 possess advantages over those of hydraulic masonry apart from the necessity in the latter instance of constant supervision to prevent scamping by leaving chinks and spaces vacant1 especially where large masses of stone or ,cyclopean rubble are used4 ,again1 should the dam be drowned by flood during its erection1 no harm would accrue were it composed of ,portland cement concrete1 whereas should it be of hydraulic mortar masonry1 the wall would probably be destroyed or1 at all events1 considerably injured by the mortar being washed out of the joints4 ,portland cement1 however1 is only suitable for situations where the foundation is absolutely firm1 as1 should there be the slightest settlement1 fissures would certainly be produced4 ,as regards foundations1 the dam of the ,puentes reservoir in ,spain is somewhat remarkable--see ,fig4 #ab4 ,its height is #afd ft41 and the profile or cross section is of precisely the same character as that of the ,alicante dam1 the latter being #ace ft4 in height1 #fe ft4 wide at the crest1 and #fe ft4 at the base1 and erected about #cjj years ago4 ,at the ,puentes dam the flanks of the valley were reliable1 but1 as must be frequently the case in such situations1 the bed of the valley was composed to a great depth of gravel1 debris1 and shaky strata4 ,the difficulty was overcome by throwing an arch1 or arches1 across the valley1 the abutments being formed by the solid rock on each side1 and building the dam upon this arching and filling in below the latter down to a sufficient depth with walling4 ,bearing in mind the sudden and great floods to which dams constructed in such situations must be subjected1 and1 if the valley be very narrow1 the probability that sufficient space at the side for a by-wash will be difficult to obtain1 it would seem reasonable that in the calculation for their section allowance should be made for the possible condition of the whole length of the dam being converted into a weir1 over which the waters may flow without risk of injury to the dam1 to a depth of1 say1 at least twice that ever probable4 ,the topping of dams by floods is not uncommon1 and if the extra strain thus induced has not been allowed for1 their destruction is nearly certain1 as instanced in more than one case in ,algeria1 where1 although the average rainfall is only #ae in4 yearly1 a depth of #f in41 or more than one-third of the annual total1 has been known to fall in twenty-four hours4 ,the ,habra dam--see ,fig4 ,no4 #ac--;completed in #ahga1 was destroyed by a sudden flood of this kind in ,december1 #ahha4 ,this reservoir1 with a storage capacity of #f1fjj1jjj1jjj gallons1 was intended for the irrigation of a cultivated bordering on the ,mediterranean and the storage of floods4 ,the height of the dam was #aaf4g ft4 and was provided with a by-wash of #cid ft4 in length1 and outlets for irrigation formed by four cast iron pipes of #ca in4 diameter through the dam4 ,it was composed of rubble set in hydraulic mortar1 the latter composed of two parts of sand to one of hydraulic lime4 ,for getting rid of the large deposits of sand to which all reservoirs in that country are liable1 two scouring outlets were provided of the same description as those in the old ,moorish dams4 ,the profile was calculated from ,delocre's formula1 and was correct in this respect1 supposing the by-wash to have been sufficient4 ,but as it was otherwise1 and the flood swept over the crest to the depth of about #c ft41 the enormous extra strain thus induced overthrew the dam and caused the destruction of several villages and the death of #bji persons4 ,it must be mentioned that when the reservoir was filling1 the water percolated through the masonry1 giving the face wall the appearance of a huge filter1 which at the time was attributed to the porous nature of the sandstone used in construction1 but which more probably was due to the washing of the green mortar out of the joints4 ,at the ,hamiz dam1 also in ,algeria1 the water was admitted in #ahhd1 but it showed immediately signs of weakness1 so that the water had to be run out and an immense retaining wall erected to strengthen the main dam4 ,algeria seems to have been singularly unfortunate as regards the success of works of this description4 ,water was admitted to the ,cheurfas reservoir in ,january1 #ahhe1 and it at once began to make its way through permeable ground at one end of the dam4 ,the flushing sluice in the deepest part of the dam had become jammed1 so that the pressure could not be relieved1 and in ,february #cj ft4 length of the dam was carried away1 causing a flood in the river below4 ,at some distance down stream was the ,sig reservoir4 ,the flood rushing down1 topped this dam by #ah ft4 and overthrew it also4 ,allusion has been made to provision for scouring out sand and deposit1 especially in the dams of ,algeria and of ,spain4 ,the amount of sand1 etc41 brought down by the floods is something enormous1 and the question of the best means of getting rid of it has occupied much attention4 ,in the old ,moorish reservoirs the flushing gallery1 piercing the lower part of the dam1 was closed by iron doors on the down stream face and blocked with timber at the upper end4 ,when required to be flushed out1 laborers passed through the gallery and broke down the timber barrier1 the silt forming a wall sufficiently thick to resist the pressure of the water for the time being1 and allow of the retreat of the ,forlorn ,hope--if the latter had luck--before giving way4 ,one method adopted in ,algeria1 which has the advantage of permitting the sediment to be utilized together with the irrigation1 this sediment being very fertilizing1 is to pump air down through hose extending to the bottom of the reservoir1 the pumps being actuated by steam power or turbine1 and the sediment thus stirred up and run off with the water through the irrigation pipes4 ,as an example of one of the early types of masonry dams in ,france1 reference may be made to ,fig4 #ac1 on which is shown an elevation and cross section of the ,lampy dam1 forming a large reservoir for feeding the ,languedoc canal4 ,i will now refer to some of the most notable masonry dams in existence1 commencing with ,france1 where perhaps the finest is that known as the ,furens1 in connection with the ,st4 ,etienne ,water ,works1 constructed between the years #ahei-ff1 and designed by the engineers ,graiff and ,grandchamps4 ,it is curved in plan1 struck with a radius of #hbh ft4 from a center on the down stream side1 and founded upon compact granite1 the footings being carried down to a depth of #c ft4 #c in4 below the surface of the rock4 ,it is of rubble masonry1 in hydraulic mortar1 carried up in courses of #e ft4 in depth4 ,the height is #agj ft4 on the up stream side and #ahd ft4 high on the lower side1 with a breadth of #i ft4 #h in4 at the crest and #aaj ft4 at the base1 and the cross section is so designed that the pressure is nearly constant in all parts1 and nowhere exceeds #ic lb4 to the square inch--#ac1cib lb4 to the square foot4 ,the contents is equal to #eb1jjj cubic yards of masonry1 and the cost of erection was #cf1jhj4 ,the capacity of the reservoir is equal to #ceb1jjj1jjj gallons4 ,the reservoir discharges into two tunnels 7see ,fig4 #aa71 driven one above the other through a hill into an adjacent valley4 ,the lower tunnel contains three cast iron pipes1 with a masonry stopping of #cf ft4 long4 ,two of these pipes are #af in4 diameter1 with regulating valves1 and discharge into a well1 from whence the water can be directed for the town supply or into the river4 ,the third pipe1 of #h in4 diameter1 is always open1 and serves to remove any deposit in the reservoir1 and to furnish a constant supply for the use of manufacturers4 ,the author drew attention to the difference in the section of the ,furens dam1 ,fig4 #aa1 as compared with that of ,alicante1 and of ,puentes1 which is similar to the latter4 ,these two last illustrate the ancient ,moorish type1 and the former that of the present day4 ,the ,gileppe dam at ,verviers1 in ,belgium1 ,fig4 #ad1 although quite recently erected1 viz41 between the years #ahfi and #ahge1 differs very much from the ,furens type1 in so far as it is of very much larger sectional area in proportion to its height1 but this is accounted for by the desire of the engineer1 ,m4 ,bodson1 to overcome the opposition to its construction1 and meet the objections and combat the fears of those whose interests--and those serious ones1 no doubt--would be affected in the event of its rupture1 the body of water stored being #b1gja1fhg1jjj gallons1 or about eight times as much as the capacity of the ,furens reservoir4 ,in addition to this1 there was another reason1 which was quite sufficient in itself to account for the extra substantiality of the dam4 ,this reservoir is for supplying water to the cloth factories of ,verviers1 on the ,belgian-,german frontier4 ,it is curved in plan to a radius of #a1fdj ft41 with a length of #gga ft41 and the additional strength of the structure due to so flat a curve is probably slight4 ,it is built of rubble masonry1 with ashlar facework1 laid in hydraulic mortar4 ,the total amount of masonry is #cbe1jjj cubic yards4 ,there are two weirs1 at a level of #f ft4 below the crest1 each #hb ft4 wide4 ,the total height1 including the foundations1 which are carried down from #c ft4 to #e ft4 into the rock1 is #aed ft41 and the breadth of the crest1 which carries a road1 is #di ft4 #c in41 and at the base #baf ft4 ,the outlet pipes are carried through tunnels1 which are driven on the curve into the hill side a considerable distance clear of each end of the dam4 ,another very important structure is the ,villar dam1 ,fig4 #ae1 in connection with the water supply of ,madrid1 and situated on the river ,lozoya4 ,the storage capacity of this reservoir is very considerable1 viz41 #d1djj1jjj1jjj1 or nearly thirteen times as great as that of ,furens4 ,the height of the dam is #afb ft41 with a breadth of #ad ft4 #i in4 at the crest4 ,it is built on the curve to a radius of #ddj ft41 and the length of the dam measured along the crest is #edf ft41 of which #aig ft4 is by-wash1 thus describing nearly one-fifth of a circle1 and consequently well designed to resist pressure4 ,the dam is built of rubble masonry in hydraulic mortar1 and cost #hj1eef4 ,the ,stony ,creek lower reservoir dam of the ,geelong water supply1 ,fig4 #af1 colony of ,victoria1 is interesting as being constructed of concrete1 in the proportion of #a to #h4 ,its erection occupied eighteen months1 and cost about #ah1jjj4 ,it is curved in plan to a radius of #cjj ft41 and the greatest depth or head of water is #eb ft4 #d in4 ,the width at the crest is only #b ft4 #h in41 although surmounted by a heavy coping of bluestone #c ft4 #c in4 broad and #a ft4 #i in4 deep4 ,there being no facility for making a by-wash at the side1 the center of the dam is dished to form a weir #cj ft4 long4 ,there are both outlet and scour pipes1 and valves of #b ft4 diameter1 and the capacity of the reservoir is #adc1ade1hcd gallons4 ,the ,paramatta dam1 in ,new ,south ,wales1 built of masonry in hydraulic mortar1 is another instance of a dam built on the curve1 and which has resisted a flood of water #d ft4 in depth over the crest2 and in the case of a dam of about #dj ft4 high across the river ,wyre1 in connection with the ,lancaster ,water ,works1 made of cement concrete in proportion of #d to #a1 there has1 according to ,mr4 ,mansergh1 frequently been a depth of #e ft4 of flow over it4 ,this dam is built to a radius of #hj ft4 only1 and as it measures #ajj ft4 along the crest1 must include about the fifth of a circle4 ,there now remain only two other examples of masonry dams1 the first being that in connection with the ,liverpool water supply1 and known as the ,vyrnwy dam1 ,fig4 #ag1 this being thrown across a stream of that name in ,north ,wales4 ,it is now under construction1 and when completed will impound an area of #a1aae acres4 ,the dam will be #a1bee ft4 long1 and formed of ,cyclopean rubble set in cement mortar1 and the interstices or spaces between the large masses of stone1 which are rough hewn and not squared1 are filled with cement concrete4 ,the proportion of the cement mortar is #b to #a4 ,these masses of stone weigh from two to eight tons each1 and it is expected that the wall will be of a most solid description1 as great care is being taken to fill up all spaces4 ,the face next to the water is cemented4 ,the area of the cross section shown on the diagram1 which is at one of the deepest points1 is #h1igb square feet1 and the height from foundation to flood level is #abi ft41 the breadth at the base being #aag ft4 #i in4 ,the existing dam of the ,new ,york water supply1 ,fig4 #ah1 known as the ,croton reservoir1 is shown on the diagram4 ,its capacity is #cfd1jjj1jjj gallons and the area #bgi acres4 ,the height is #gh ft4 and width at crest #h ft4 #f in41 and is built of masonry in hydraulic mortar4 ,the face walls are of stone laid in courses of #ad in4 to #bf in41 and are vertical on the up stream side1 and with a batter of #a in #b on the down4 ,the hearting is of concrete for a depth of #de ft4 from the top1 and the remaining depth is in ,cyclopean rubble4 ,at ,fig4 #ai is shown the section of the ,quaker ,bridge dam1 which when completed will be the largest structure of the kind in existence4 ,it is situated on the ,croton ,river1 which is a tributary of the ,hudson1 about four miles below the present ,croton dam4 ,the length will be #a1cjj ft4 and the height #agj ft4 above the river bed1 or #bgg ft4 above the foundation4 ,the water by-wash is #g ft4 below the crest1 and the dam is #bf ft4 broad at the crest and #baf ft4 at the base4 ,the capacity of the reservoir will be #cb1jjj1jjj1jjj gallons1 or nearly a hundred times as great as that of ,furens4 ,the geological formation at the site is sienitic gneiss4 ,the cost of the dam is estimated at #ejj1jjj4 ,illustration3 ,,typical ,,masonry ,,and ,,earthwork ,,dams ,,of ,,the ,,world4 ,the accompanying table gives the pressures to which various dams are subjected1 and it may be noted with regard to the weight of water1 generally assumed as #fb4d lb4 per cubic foot1 that it will1 in some districts1 in time of flood1 carry so much matter in suspension as to be increased to as much as #ge lb4 weight1 or an addition of #bj per cent41 which1 it may be easily imagined1 will affect the conditions of stability very seriously4 ,,table ,,of ,,maximum ,,pressures4 ,lb4 per sq4 in4 ,gileppe 7,verviers74 #hh ,furens 7,st4 ,etienne74 #ic ,puentes4 #aab ,de ,ban4 #aac ,st4 ,chamond4 #aad ,alicante4 #aed ,hamiz 7,algeria7--failed4 #aeg ,habra 7,algeria7--failed4 #ahe ,a diagram comparing the section derived from ,molesworth's formula and those of ,furens1 ,gileppe1 ,vyrnwy1 and ,quaker ,bridge1 is given at ,fig4 #bj1 the limit of pressure assumed for the masonry being #ic lb4 per square inch1 which is that of the ,furens1 the ,gileppe being #hh4 99 99 99 99 99 ,,new ,,dredging ,,machinery4 ,we illustrate the new dredger ,ajax1 recently built for ,mr4 ,geo4 ,f4 ,smith1 of ,stockton1 ,cal4 ,the dredger has now been working for two weeks at ,wakefield1 and1 we are informed1 is giving entire satisfaction2 having been repeatedly timed to be discharging clay at the rate of #bbj cubic yards per hour4 ,illustration3 ,,the ,,new ,,dredger ,,ajax4 ,the ,ajax is almost a duplicate of the last dredger designed by ,mr4 ,ferris for levee building on ,roberts ,island1 with such modifications and improvements as have suggested themselves in the two years it has been working4 ,the hull1 oval in plan1 is #cf ft4 #aj in4 by #fj ft4 over all2 it has four solid fore and aft bulkheads1 and a well hole #e #ab ft4 at one end for the bucket ladder4 ,the main engine is #aj #bd1 operating1 by bevel gearing and a #c in4 vertical shaft1 a #d sided upper tumbler with #ba in4 sides4 ,this engine works also a gypsy shaft for swinging1 and the conveyer that carries the mud ashore4 ,a steam hoist with #f #aa engines raises and lowers the bucket ladder4 ,the buckets1 at #d foot centers1 have a struck capacity of #e cubic feet1 and are speeded to deliver from #ah to #bj a minute1 according to the character of the material being handled4 ,they are of boiler iron1 with a #e in4 steel nosing4 ,the links are of wrought iron1 with cast bushings4 ,the lower tumbler is hexagonal1 on a #d in4 shaft4 ,the conveyer1 projecting #gb ft4 from the center of the boat1 consists of a #e ply rubber belt #cf in4 wide2 running over iron drums at each end and intermediate iron friction rollers at #c foot centers4 ,ratchet and pinion on each side of conveyer ladder give means for taking up the slack of the belt and adjusting the drums to maintain them parallel4 ,this conveyer is the important feature of the dredge4 ,it is entirely satisfactory in its working and delivers its material1 as nearly as may be1 in a dry state upon the levee4 ,it was feared the rubber belt would be shortlived1 but a #d ply belt ran continuously for over two years on the ,roberts ,island dredge before it needed replacing4 ,the boiler is of the marine type1 #eb in4 by #aj ft4 #f in41 with #c in4 tubes and #ad in4 flues2 and burns about #a1djj lb4 of steam coal in a day of #ab hours4 ,there are three pumps aboard--a hand force pump for washing boiler1 a plunger pump for boiler feed1 and an ,evans steam pump to throw a jet of water into the delivery hopper when digging in any very tenacious material4 ,all three are connected with the boiler4 ,water tanks below deck serve to trim the boat and furnish a supply for the boiler4 ,the dredger cuts by swinging on a center spud #af in4 in diameter1 and moves forward from #h to #aj ft4 at each fleet4 ,the ,roberts ,island dredger1 of which the ,ajax is an improved copy1 handles steadily #gjj yards per day of #ab hours1 in the stiffest and most tenacious clay in which it has been worked2 and ranges from that average to #a1ejj yards per day in soft1 peaty mud4 ,the ,ajax was built by ,farrington1 ,hyatt ,co41 of the ,stockton ,iron ,works4 ,this type of dredger can be built for about #ab1ejj1 and we are informed can be relied on for a monthly average of #bf1jjj yards in any material met with in the overflowed lands near ,stockton1 delivered #ej ft4 ashore1 at a height of #aj or #ab ft4 above the ground line4--,min4 and ,sci4 ,press4 99 99 99 99 99 ,,the ,,flexible ,,girder ,,tramway4 ,this is an ingenious proposition for utilizing a modification of the wire tramway system for overcoming obstacles 7while retaining the ordinary wire tramway or any light railway on other parts of the line71 made by ,mr4 ,charles ,ball1 of ,london4 ,the flexible girder tramway is an improved system of constructing a modification of the well known and extensively used rope or wire tramway1 and it is claimed that it will revolutionize the transport of the products of industrial operations from the place of production to the works or manufactory1 railway station1 shipping ports1 or place of consumption2 and that in the result the introduction of the flexible girder tramway will in many cases enable profits to be earned in businesses which have hitherto been unremunerative4 ,it is declared to be at once simple1 cheap1 durable1 and efficient4 ,the improvement consists in the employment1 in addition to the usual tram wire 7a hempen rope1 a wire rope1 or a metallic or other rod71 along which the load is transported1 of a second or suspension wire or rope to which the tram wire is connected by tension rods or their equivalent at intervals between the rigid supports or piers1 the object being to diminish or distribute the sagging or deflection of the tram wire1 and thus lessen the steepness of the gradients over which the load has to be transported4 ,the combined tram wire1 tension rods1 suspension wire1 and accessories are1 for convenience1 designated a flexible girder4 ,another improvement consists in using1 when a double line is employed1 stretchers or crossheads to keep the flexible girders nearly parallel to each other1 so that when necessary the load to be transported may be suspended from or borne by both tram wires jointly or simultaneously1 thus permitting a load of greater weight than that for which each single tram wire is intended to be carried over the system4 ,one indisputable claim for confidence in the flexible girder principle is said to be that1 although the peculiar combination of parts constitutes a striking and valuable novelty1 it contains nothing that has not been proved by the experience of years--nay1 generations--to be useful1 economic1 and reliable4 ,the usual practice followed in erecting suspension bridges is applicable in mounting the line1 and the carriers1 supports1 and carriages may be of any of the usual forms4 ,for the rapid removal of limited loads wire tramways are in universal favor1 and are recognized not only as very economic and quickly constructed1 but also as being in many cases the only means of transport available except by the adoption of elaborate and costly engineering works4 ,it has1 it seems1 been suggested by some who have examined the construction of the flexible girder tramway for mineral and produce traffic that it would be an additional advantage if arrangements were made for the carriage of small loads--half a dozen or so--of passengers1 the primary intention being to carry the workpeople backward and forward between comparatively inaccessible mines1 works1 or plantations and a neighboring village or town4 ,compared with every other system where the line over which the load travels is elevated1 the flexible girder tramway is claimed to possess many advantages--the center of gravity is kept well down1 the liability of the wheels leaving the line is reduced to the minimum1 the gradients are the easiest that can be obtained1 there is an entire absence of jolting and extremely little vibration1 and the motion is altogether smooth and regular2 yet it is very questionable whether1 when human life is at stake1 any but an ordinary ground line should be relied upon4 ,a living freight is far more liable than a dead freight to move during the journey2 and as the safety of all overhead lines depends upon what is scientifically designated unstable equilibrium1 the flexible girder tramway is not recommendable for passenger lines1 although it can1 of course1 be fitted for passenger traffic1 a suitable vehicle and ten or a dozen good stout workmen coming well within a two-ton load1 which can be readily carried4 ,illustration3 ,,ball',s ,,flexible ,,wire ,,tramway4 ,rope traction or animal traction--practically speaking--is alone available for wire tramways 7that is to say1 if the trains are each to be propelled by its own locomotive--whether steam1 springs1 or electricity--the cost of construction and maintenance becomes so serious that overhead lines1 however well designed1 are no longer economic72 and experience gained with rope traction in numerous collieries in the ,north of ,england and ,lancashire districts--where it is highly appreciated--has shown that1 all circumstances considered1 the endless rope is preferable4 ,the chief objection urged against wire tramways as hitherto constructed has been that the sag of the rope has sometimes caused annoyance to those using the property passed over1 and has always added much to the cost of traction1 owing to the increased power required for moving the load2 this has also resulted in vastly increased wear and tear and the rapid deterioration and destruction of the wire rope4 ,the flexible girder system so reduces the sag that the maximum economy and durability are obtained1 and the gradients over which the load has to travel can be made as easy and regular as those upon an ordinary railway4 ,this advantage will be the more readily appreciated when it is considered that with a given load on a gradient of #a in #cj the resistance due to gravity alone is #bjj per cent4 greater than on a gradient of #a in #aej1 and that the retardation and wear and tear due to friction1 greater curves1 and imperfections increase still more rapidly with increase of gradient1 soon rendering the old sagging wire line practically worthless4 ,to construct an entire line of flexible girders would be not only unnecessary1 but so costly as to neutralize any advantage which it may possess1 yet for surmounting occasional obstacles the claim made for it--that it will sometimes permit of a line otherwise impracticable being cheaply made--seems justified4 ,one can readily imagine a light narrow gauge line costing #a1jjj per mile being laid1 for example1 between a mine and the shipping place1 and that a swamp1 river1 or valley would cost more to bridge over than the whole line besides4 ,if at this obstacle the trucks or carriages could be lifted bodily1 passed along the flexible girder1 and again placed on the line the other side of the obstacle1 the advantage to be derived is obvious2 and as the flexible girder is really little more than a suspension bridge minus the platform1 and having but two suspension wires1 the cost and the difficulties should both be very small4--,industrial ,review4 99 99 99 99 99 ,,bozerian',s ,,refrigerant ,,punkas4 ,punkas 7also called pankasor tankas7 are apparatus that serve for fanning rooms throughout the entire extent of ,english ,india4 ,these devices consist of a light wooden frame covered with canvas1 from the bottom of which depends a fringe4 ,these frames are suspended from the ceiling in such a way as to occupy nearly the entire width and length of the room4 ,to the base of the frame is attached a cord which passes over a wheel1 and which is pulled by a ,hindoo domestic4 ,after the frame has been lifted1 a weight fastened to the lower part causes it to fall back again4 ,the result of the continuous motion of this colossal fan is a coolness that is highly appreciated in a country where the temperature is at times incredibly high1 and where1 without the factitious breeze created by the punka1 living would not be endurable4 ,this breeze prevents perspiration1 or evaporates the same as soon as it is formed4 ,sometimes it sinks to a light zephyr2 then1 if you are reading or writing1 you may continue your work1 but in a distracted way1 with a moist brow1 and with a feeling of annoyance that soon makes you leave book or pen4 ,illustration3 ,,fig4 #a4--,,tent ,,or ,,table ,,fan ,,or ,,punka4 ,looking around you1 you find the punka immovable4 ,the bahi still holds the cord that pulls it1 but it is because he has tied it to his hand4 ,he has gently slid to the floor in a squatting posture4 ,he is asleep and you are burning4 ,a vigorous exclamation brings him to his feet all standing1 and he begins to pull the punka with all his might1 and you have a feeling of ease and coolness4 ,it is like the passage from an attack of fever to a state of comfort in an intermittent disease4 ,so the punka is seen everywhere--in the temple and court room and other public places1 as well as in private dwellings4 ,it is one of the first things to astonish the ,european upon his arrival in ,india1 and it is not long before he has to bless the happy invention4 ,although1 in a country where the temperature generally reaches1 and even often exceeds1 #dj ,c41 it is absolutely necessary to obtain by every means possible a factitious coolness without which the ,indies would not be habitable for ,europeans2 and although there is no hesitancy in putting up these punkas everywhere to be maneuvered by bahis1 the elevation of the temperature is not such in ,france that we are obliged to have recourse to such processes4 ,but1 without being forced thereto by nature1 it is none the less true that we are often the more incommoded by heat in that we are not accustomed to it1 and that in southern ,france1 at certain hours of the day1 such heat becomes absolutely unbearable4 ,we can1 it is true1 obtain a little air by moving a fan1 but1 aside from the fact that this exercise soon becomes tiresome1 it prevents the use of the hand that is fanning4 ,illustration3 ,,fig #b4--;,,an ,,apartment ,,fan4 ,the new apparatus which have just been devised by ,mr4 ,g4 ,bozerian permit of one's fanning himself all day long if he wants to1 without any fatigue1 and while he is eating1 reading1 writing1 etc4 ,in one of these apparatus1 designed to be used in the open air 7,fig4 #a71 we find a table1 a tent1 and a fan combined2 but as each part is independent1 we can have the table and fan without tent1 or the fan and pedals alone without table or tent4 ,under the tent there is arranged a frame which pivots freely in apertures formed in the uprights that support both the tent and table4 ,this frame is connected1 through two levers1 with the pedals upon which one's feet rest4 ,the motion of the pedals is an alternating one like those of sewing machines2 but while in the case of the latter a pressure has to be exerted that soon becomes very tiresome1 the motion in ,mr4 ,bozerian's apparatus is so easy that it is only necessary to raise the toes of each foot in succession in order to produce a swing of the fan through the weight alone of the foot that is pressing4 ,the frame1 which when at rest hangs perpendicularly1 describes about a quarter of a circle when the extremity of the foot is raised about an inch4 ,in consequence of the absence of passive resistances1 motion occurs without any stress1 and almost mechanically1 giving air not only to him who is actuating the fan1 but also to his vis-a-vis4 ,fig4 #b represents an apartment apparatus designed to be placed in front of a table or desk1 in order that one can fan himself while eating or writing4 ,being mounted upon casters1 it can be readily moved about from one place to another4 ,at the extremity of a wooden support1 whose height may be varied at will1 there is arranged a flexible fan whose handle is fixed near a pulley4 ,a small piece of lead forms the counterpoise of the fan1 which is thus completely balanced4 ,over the pulley runs a cord1 each end of which is attached to a pedal4 ,it will be seen that the alternate motion of these pedals must cause a rotation of the pulley in one direction or the other1 and that consequently the fan will rise or fall more or less rapidly1 and give a quantity of air that varies according to the rapidity with which the toes are moved4--,la ,nature4 99 99 99 99 99 ,,punkas4 ,footnote3 ,extract from a lecture recently delivered at ,bombay4 ,by ,j4 ,,wallace1 ,c4,e4 ,the function of a punka is to cause a current of air to pass the human body so that the animal heat may escape more rapidly4 ,this has nothing to do with ventilation2 for if the punka were used in a closed room1 it would still produce a cooling effect on the skin4 ,let us for a moment examine into what takes place in this operation1 for a clear idea of the cause of our sensations of heat is absolutely necessary to enable us to go directly to the simplest and best form of remedy4 ,the heat we feel1 and which sometimes renders us uncomfortable1 is produced within us by the slow combustion of the food we eat4 ,this heat continues to escape from the whole surface of the body during the whole lifetime1 and if anything occurs to arrest it to any great extent1 the result is fatal4 ,in cold weather1 and especially when there is much wind1 the animal heat escapes very rapidly from the body1 and extra clothing is used1 not for any heat it imparts1 but simply because it interrupts the escape of the heat1 and thus maintains the temperature of the skin--that part of us which is most sensible of change of temperature4 ,it is a wonderful fact that the heat of the interior of the body varies very little in a healthy man between ,india and ,greenland4 ,the skin may bear a good many degrees of change of temperature with impunity1 but the blood will only suffer a very small variation from the normal temperature of #ih-d_/aj ,fahrenheit without serious consequences4 ,well1 to keep the skin at an agreeable temperature in ,india we generally wear a minimum of clothing1 and when there is no breeze1 we try to produce one with the punka4 ,the escape of animal heat from the body forms a subject which is much more complicated1 and much more important1 than the one we have met to consider1 but it is impossible within the limits of our time to refer to it1 except in the measure that is strictly necessary to elucidate the principles that should control the construction of the punka4 ,it has often been said that every engineer on his arrival in ,india sets about improving this useful apparatus2 but if we may judge from the endless variety of forms which may be seen in shops and offices1 in public and in private buildings1 no general principle of construction has been recognized1 and the punka1 as we see it1 seems to depend1 for its form1 more upon the taste of the workman who makes it than on anything else4 ,we shall begin by directing our attention to the suspended punka1 which is usually hung from the ceiling1 and put in movement by a cord4 ,the object of this class of punka is to produce a downward current of air by swinging to and fro1 and the best punka is the one which throws downward the greatest quantity of air with the smallest applied force4 ,the swinging punka is one of the simplest forms of mechanism2 it can be fitted up with the most primitive materials1 and however badly made1 it will always have some effect4 ,this fact has its good and its bad aspects2 it brings a certain comfort within the reach of all1 but it removes a great part of that necessity which1 as we all know1 is the mother of invention4 ,there are some very important natural laws which are illustrated in the punka4 ,the first is that which governs the movement of the pendulum4 ,the number of swings it makes per minute depends on the length of the suspending cords2 a pendulum three feet long will swing #fb times per minute1 and a pendulum six feet long will swing #dd times per minute4 ,whether the swings are long ones or short ones1 the number per minute is still the same4 ,you cannot1 therefore1 alter the natural rate of movement of a punka unless you pull it at both sides4 ,the next law is that which determines that the angles of incidence and of reflection are equal4 ,this in simple language means that it is useless to expect a good downward current of air from a slow moving and heavy punka1 with long suspending cords which keep it nearly always in a vertical position to its plane of movement4 ,striking the air squarely as it does in its forward and backward movement1 it throws almost as much air upward as downward1 and of course all the air that is propelled in any other than a downward direction represents just so much power wasted4 ,one more law1 and then we may proceed to demonstration4 ,as the air weighs #j4jgb lb4 per cubic foot at #hb ,fahrenheit1 and as a considerable quantity of air is put in motion1 the power required to drive a punka depends upon the quantity of air it puts in motion in a given time4 ,the useful effect is a separate matter2 it depends on the amount of air thrown in a downward direction4 ,to summarize2 all punkas of the same size or surface1 and going at the same speed1 require the same amount of pulling4 ,the best one is that which will throw down more air than any other of the same size4 ,to obtain the greatest result from the power expended in driving it1 the punka should be placed as near as possible to the person to be cooled1 as the loss of effect1 due to distance1 increases not in direct ratio1 but in proportion to the square of the distance between punka and person4 ,if at two feet of distance he receives one eighth of the total effect1 he will at four feet of distance obtain only one thirty-second part4 ,in practice1 the punka should just clear his head when standing1 and the weighting of the curtain should be of some yielding material1 so as not to damage any person who might stand in its course4 ,we shall now proceed to examine several forms of punka1 all made to the same size1 and1 for purposes of comparison1 we shall drive them all at the same speed4 ,and in order that their effects may be visible to you1 ,i have prepared an indicator which resembles more than anything else the keyboard of a piano4 ,it consists of a series of balanced levers with blades or keys attached1 forming a keyboard four feet long4 ,the levers1 each three feet long1 are delicately hung on fine brass centers1 and each lever is counterbalanced by a weight hung in a vessel of water1 which acts as a hydraulic brake1 and checks any spasmodic movement in the apparatus4 ,on the end of each blade is fixed a disk of white ,bristol board four inches in diameter1 forming a row which faces the audience4 ,this apparatus is so sensitive that a slight change in the humidity of the atmosphere is sufficient to throw it out of balance4 ,the power required to drive a punka is nearly all due to the resistance of the air2 that part due to the force of gravity1 and the friction of the suspending joints1 is scarcely worth counting4 ,we may readily observe the effect of the resistance of the air by swinging two pendulums of equal length and having each a large cardboard disk attached4 ,one of the disks shall present its edge to the line of movement1 and the other its face4 ,exp4 #a4--,they are now swinging1 and being both of the same gravity length1 they should swing together and for an equal length of time4 ,this they would do in a vacuum1 but you have already observed that one of them is lagging1 and will evidently soon come to a standstill4 ,it is the one facing the air4 ,if punkas were pulled from both sides1 they might be made very much lighter than they are at present1 but for the sake of simplicity a single pull is preferred4 ,they must1 therefore1 be made of such a weight that they will swing nearly as far on the opposite side as they are pulled on the near side2 any greater weight is useless and only serves to wear out the suspending cords1 which1 by the way1 are nearly always too numerous and too thick for their purpose4 ,exp4 #b4--;,here is a panel punka which we shall try to use without the customary swing bar4 ,it is of calico stretched on a light wooden frame1 and you will be able to judge if it swings equally on each side of the post which supports it4 ,the irregularity of its movement shows that it is too light1 so we shall add1 by way of swing bar1 a bar of round iron one and a quarter inch thick4 ,exp4 #c4--;,it is now swinging regularly1 and experiments have already proved that the swing bar should not be lighter than this one1 which weighs four and a sixth lb4 per foot of length4 ,iron is the best material for this purpose1 as it offers the smallest surface to the resistance of the air4 ,the length of the suspending cords is usually a matter of accident in the construction of a punka1 but a little attention to the subject will soon convince us that it is one of the most important considerations4 ,the limit of movement of a punka is to be found in the man who pulls it4 ,twenty-four pulls a minute of a length of #cf inches give in practice a speed of #afh linear feet to the punka curtain4 ,this speed is found to produce a current sufficiently rapid for practical purposes1 and twenty-four pulls or beats per minute correspond to a length of suspending cord of fifty inches4 99 99 99 99 99 ,,how ,,to ,,make ,a ,,kite ,,without ,a ,,tail4 ,the following is the method of making a kite without a tail3 ,all the calculations necessary in order to obtain the different proportions are based upon the length of the stick1 ,a',a1 employed4 ,such length being found1 we divide it by ten1 and thus obtain what is called the unit of length4 ,with such unit it is very easy to obtain all the proportions4 ,the bow1 ,k',k1 consists of two pieces of osier each #e units in length1 that form1 through their union1 a total length of #g units4 ,illustration3 ,,kite ,,without ,a ,,tail4 ,after the bow has been constructed according to these measurements1 it only remains to fix it to the stick in such a way that it shall be two units distant from the upper end of the stick4 ,the balance1 ,,cc'1 whose accuracy contributes much to the stability of the whole in the air1 consists of a string fixed at one end to the junction1 ,d1 of the bow and stick1 and at the other to the stick itself at a distance of three units from the lower extremity4 ,next1 a cord1 ,b1 is passed around the frame1 and the whole is covered with thin paper4 ,before raising the kite1 the string1 which hangs from ,k'1 is made fast at ,k in such a way as to cause the bow to curve backward4 ,this curvature is increased or diminished according to the force of the wind4 ,nothing remains to be done but to attach the cord to the balance1 and raise the kite4--,la ,nature4 99 99 99 99 99 ,,apparatus ,,for ,,drying ,,flour4 ,the accompanying drawing represents a simple but effective apparatus for drying flour and ascertaining the quantity of water contained therein4 ,it consists of four pieces1 the whole being made of block tin4 ,a is a simple saucepan for containing the water4 ,b is the lid1 which only partially covers the top of the pan1 to which it is fixed by two slots1 a hole being left in the middle for the placing of the vessel which contains the flour to be operated upon1 and is dropped in in the same way as the pan containing the glue is let into an ordinary glue pot4 ,c is the spout1 which serves as an outlet for the steam arising from the boiling water4 ,d is the vessel in which the flour is placed to be experimented upon2 and ,,ee are the funnels of the lid which covers the said vessel1 and which serve as escapes for the steam arising from the moisture contained in the flour4 ,illustration3 ,,apparatus ,,for ,,drying ,,flour ,directions for use4--,partially fill the pan with water and allow it to boil4 ,place a given quantity of flour in the inner vessel1 ,d1 taking care first to weigh it4 ,subject it to the action of the boiling water until it is perfectly dry1 which will be indicated by the steam ceasing to issue from the funnels4 ,then weigh again1 and the difference in the weight will represent the quantity of moisture contained in it1 dried at a temperature of #bab degrees ,fahr41 that of boiling water4--,the ,miller4 99 99 99 99 99 ,,apparatus ,,for ,,manufacturing ,,bouquets4 ,for some years past1 the sale of flowers has been gradually increasing4 ,into the larger cities1 such as ,paris for example1 they are introduced by the car load1 and along about the first of ,january the consumption of them is extraordinary4 ,all choice flowers are now being cultivated by improved methods that assure of an abundant production of them4 ,what twenty years ago would have appeared to be an antiquated mechanism1 viz41 an apparatus for making bouquets1 has now become a device of prime necessity by reason of the exigencies of an excessive demand4 ,mr4 ,myard1 a gardener of ,chalon-sur-,saone1 and vice-president of the horticultural society of that city1 has devised a curious apparatus1 which we represent herewith from a photograph4 ,this bouquet machine1 which the inventor styles a bouquetiere1 consists of a stationary rod 7shown to the right of the figure71 upon which slides a spool wound with twine1 and the lower part of which is provided with three springs for keeping the twine taut4 ,a horizontal arm at the top supports a guide or pattern whose curve is to be followed1 on placing the flowers in position4 ,this arm is removed or turned aside after the binding screw has been loosened1 in order that the rod to the left that carries the bouquet may be taken out4 ,a guide1 formed of a steel ribbon1 is fixed to the arm and to its movable rod by means of binding screws1 which permit of its being readily elongated4 ,this central rod can be raised or lowered at will1 and1 owing to these combinations1 every desired form of bouquet may be obtained4 ,illustration3 ,,apparatus ,,for ,,making ,,bouquets4 ,the rod to the left is provided with a steel pivot1 and contains several apertures1 into which a pin enters1 thus rendering it easy to begin bouquets at different heights4 ,the bouquet is mounted upon the rod to the left1 as shown in the figure4 ,the pin passes through the rod and enters a loop formed at the extremity of the twine1 and thus serves as a point of support1 and prevents the bouquet from falling1 no matter what its weight is4 ,when the pin is removed in order that the bouquet may be taken out1 the loop escapes4 ,at the lower part of the rod upon which the bouquet is mounted1 there is a collar with three branches1 by means of which a rotary motion is given to the flowers through the aid of the hand4 ,the twine used for tying is thus wound around the stems4 ,when the apparatus is in motion1 the twine unwinds from the spool1 and winds around the rod that carries the flowers1 and twists about and holds every stem4 ,an experienced operator can work very rapidly with this little apparatus1 which has been constructed with much care and ingenuity1 and which enters into a series of special mechanisms that is always of interest to know about4 ,the manufacturer was advised to construct his apparatus so that it could be run by foot power1 but1 after some trials1 it was found that the addition of a pedal and the mechanism that it necessitates was absolutely superfluous1 the apparatus working very well such as it is4--,la ,nature4 99 99 99 99 99 ,continued from ,,supplement1 ,no4 #efg1 page #ijeg4 ,,radii ,,of ,,curvature ,,geometrically ,,determined4 ,by ,prof4 ,c4,w4 ,,maccord1 ,sc4,d4 ,,no4 ,,vii4--,,path ,,of ,a ,,point ,,on ,a ,,connecting ,,rod4 ,the motion of the connecting rod of a reciprocating steam engine is very clearly understood from the simple statement that one end travels in a circle and the other in a right line4 ,from this statement it is also readily inferred that the path of any point between the centers of the crank and crosshead pins will be neither circular nor straight1 but an elongated curve4 ,this inference is so far correct1 but the very common impression that the middle point of the rod always describes an ellipse is quite erroneous4 ,the variation from that curve1 while not conspicuous in all cases1 is nevertheless quite sufficient to prevent the use of this movement for an elliptograph4 ,to this there is1 abstractly1 one exception4 ,referring to ,fig4 #bb in the preceding article1 it will be seen that if the crank ,,oh and the connecting ,,he are of equal length1 any point on the latter or on its prolongation1 except ,e1 ,h1 and ,f1 will describe an exact ellipse4 ,but the proportions are here so different from anything used in steam engines 7the stroke being four times the length of the crank71 that this particular arrangement can hardly be considered as what is ordinarily understood by a crank and connecting rod movement1 such as is shown in ,fig4 #bc4 ,the length ,,de of the curve traced by the point ,p will evidently be equal to ,a',b'1 the stroke of the engine1 and that again to ,,ab1 the throw of the crank4 ,the highest position of ,p will be that shown in the figure1 determined by placing the crank vertically1 as ,,oc4 ,at that instant the motions of ,c and ,c' are horizontal1 and being inclined to ,,cc' they must be equal4 ,in other words1 the motion is one of translation1 and the radius of curvature at ,p is infinite4 ,to find the center of curvature at ,d1 assume the crank pin ,a to have a velocity ,aa4 ,then1 since the rod is at that instant turning about the farther end ,a'1 we will have ,dd for the motion of ,d4 ,the instantaneous axis of the connecting rod is found by drawing perpendiculars to the directions of the simultaneous motions of its two ends1 and it therefore falls at ,a'1 in the present position4 ,but the perpendicular to the motion of the crank pin is the line of the crank itself1 and consequently is revolving about ,o with an angular velocity represented by ,,aoa4 ,the motion of ,a' is in the direction ,a',b'1 but its velocity at the instant is zero4 ,hence1 drawing a vertical line at ,a'1 limited by the prolongation of a,o1 we have ,a'a' for the motion of the instantaneous axis4 ,therefore1 by drawing a'd1 cutting the normal at x1 we determine ,dx1 the radius of curvature4 ,placing the crank in the opposite position ,,ob1 we find by a construction precisely similar to the above1 the radius of curvature ,ez at the other extremity of the axis of the curve4 ,it will at once be seen that ,ez is less than ,dx1 and that since the normal at ,p is vertical and infinite1 the evolute of ,,dpe will consist of two branches x,n1 z,m1 to which the vertical normal ,,pl is a common asymptote4 ,these two branches will not be similar1 nor is the curve itself symmetrical with respect to ,,pl or to any transverse line2 all of which peculiarities characterize it as something quite different from the ellipse4 ,illustration3 ,,fig4 #bc4 ,illustration3 ,,fig4 #bd4 ,illustration3 ,,fig4 #be4 ,moreover1 in ,fig4 #bb1 the locus of the instantaneous axis of the trammel bar 7of which the part ,,eh corresponds to the connecting rod1 when a crank ,,oh is added to the elliptograph there discussed7 was found to be a circle4 ,but in the present case this locus is very different4 ,beginning at ,a'1 the instantaneous axis moves downward and to the right1 as the crank travels from ,a in the direction of the arrow1 until it becomes vertical1 when the axis will be found upon ,c',r1 at an infinite distance below ,,ab'1 the locus for this quarter of the revolution being a curve ,a',g1 to which ,c',r is an asymptote4 ,after the crank pin passes ,c1 the axis will be found above ,,ab' and to the right of ,c',r1 moving in a curve ,,hb'1 which is the locus for the second quadrant4 ,since the path of ,p is symmetrical with respect to ,,de1 the completion of the revolution will result in the formation of two other curves1 continuous and symmetrical with those above described1 the whole appearing as in ,fig4 #bd1 the vertical line through ,c' being a common asymptote4 ,in order to find the radius of curvature at any point on the generated curve1 it is necessary to find not only the location of the instantaneous axis1 but its motion4 ,this is done as shown in ,fig4 #be4 ,p being the given point1 ,,cd is the corresponding position of the connecting rod1 ,,oc that of the crank4 ,draw through ,d a perpendicular to ,,od1 produce ,,oc to cut it in ,e1 the instantaneous axis4 ,assume ,c ,a perpendicular to ,,oc1 as the motion of the crank4 ,then the point ,e in ,,oc produced will have the motion ,,ef perpendicular to ,,oe1 of a magnitude determined by producing ,,oa to cut this perpendicular in ,f4 ,but since the intersection ,e of the crank produced is to be with a vertical line through the other end of the rod1 the instantaneous axis has a motion which1 so far as it depends upon the movement of ,c only1 is in the direction ,,de4 ,therefore ,,ef is a component1 whose resultant ,,eg is found by drawing ,,fg perpendicular to ,,ef4 ,now ,d is moving to the left with a velocity which may be determined either by drawing through ,a a perpendicular to ,,cd1 and through ,c a horizontal line to cut this perpendicular in ,h1 or by making the angle ,,dei equal to the angle ,,cea1 giving on ,,do the distance ,,di1 equal to ,,ch4 ,make ,,ek ,,di or ,,ch1 complete the rectangle ,,kegl1 and its diagonal ,,es is1 finally1 the motion of the instantaneous axis4 ,,ep is the normal1 and the actual motion of ,p is ,,pm1 perpendicular to ,,ep1 the angle ,,pem being made equal to ,,cea4 ,find now the component ,,en of the motion ,,es1 which is perpendicular to ,,ep4 ,draw ,,nm and produce it to cut ,,ep produced in ,r the center of curvature at ,p4 ,this point evidently lies upon the branch z,m of the evolute in ,fig4 #bc4 ,the process of finding one upon the other branch x,n is shown in the lower part of the diagram1 ,fig4 #be4 ,the operations being exactly like those above described1 will be readily traced by the reader without further explanation4 99 99 99 99 99 ,,automatic ,,commutator ,,for ,,incandescent ,,lamps4 ,incandescent electric lighting1 already pushed to such a degree of perfection in the details of construction and installation1 continually finds new exigencies that have to be satisfied4 ,as it is more and more firmly established1 it has to provide for all the comforts of existence by simple solutions of problems of the smaller class4 ,take for example this case3 ,suppose a room1 such as an office1 lighted by a single lamp4 ,the filament breaks2 the room becomes dark4 ,the bell push is not always within reach of the arm1 and it is by haphazard that one has to wander around in the dark4 ,this is certainly an unpleasant situation4 ,the comfort we seek for in our houses is far from being provided4 ,m4 ,clerc1 the well known inventor of the sun lamp1 has tried to overcome troubles of this sort1 and has attained a simple1 elegant1 and at the same time cheap solution4 ,the cut shows the arrangement4 ,the apparatus is connected at the points1 ,,bb'1 with the lighting circuit4 ,the current entering by the terminal1 ,b'1 passes through the coils of a bobbin1 ,s1 before reaching the points of attachment1 a and b1 of the lamp1 ,l1 the normally working one4 ,thence the circuit runs to ,b4 ,within the coil1 ,s1 is a small hollow cylinder1 ,t1 of thin sheet iron1 which is raised parallel with the axis of the bobbin during the passage of the current through the latter4 ,at its base the cylinder is prolonged into two little rods1 h and h'1 which plunge into two mercury cups1 ,g and ,g'4 ,the cut shows that one of the cups1 ,g'1 is connected to the terminal1 ,b'1 and the other1 ,g1 to the terminal1 a'1 of the other lamp1 ,l'4 ,an inspection of the cut shows just what ensues when an accident happens to the first lamp while burning4 ,the first circuit being broken at ab1 the magnetizing action of the current in the bobbin ceases1 the cylinder1 ,t1 descends1 and the rods1 h and h'1 dip into the mercury4 ,it follows that the current1 always starting from the terminal1 ,b'1 will by means of the cups1 ,g and ,g'1 pass through the lamp1 ,l'1 to go by the original return wire to ,b4 ,illustration ,the substitution of the lamp1 ,l1 for ,l' is almost instantaneous4 ,it can scarcely be perceived4 ,it goes without saying that such an arrangement of automatic commutation is applicable to lamps with two or more filaments of which only one is to be lighted at a time4 ,the apparatus costs little1 and can be made as ornamental as desired4 ,no exaggeration is indulged in if we pronounce it simple and ingenious4 ,it may be used in a great variety of eases4 ,the diameter of the wire is #ee_/ajj 7#bb mm471 its length eighteen meters 7#fj feet71 its resistance one ohm2 ampere is needed to work it1 and less than a watt is absorbed by it4--,electricite4 99 99 99 99 99 ,,definitions ,,and ,,designations ,,in ,,electrotechnics4 ,we may discourse for some time to come upon the uniformity of electric language1 for universal agreement is far from being established4 ,an important step toward the unity of this language was taken in #ahha by the congress of ,paris1 which rendered the use of the ,c4,g4,s4 system definitive and universal4 ,this labor was completed in #ahhd by the meeting of a new congress at ,paris1 at which a definition of the ,c4,g4,s4 and practical units was distinctly decided upon4 ,that the unit of light defined by the congress has not rapidly come into favor is due to the fact that its practical realization is not within everybody's reach4 ,the work of unification should not come to a standstill on so good a road4 ,how many times in scientific works or in practical applications do we find the same physical magnitude designated by different names1 or even the use of the same expression to designate entirely different things6 ,the result is an increase of difficulties and confusions1 not only for persons not thoroughly initiated into these notions1 but also for adepts1 even1 in this new branch of the engineer's art4 ,the effects of such confusion make themselves still further felt in the reading of foreign publications4 ,thus1 for example1 in ,germany that part of a dynamo electric machine that is called in ,france the induit 7armature7 is sometimes styled anker1 and more rarely armatur4 ,the north pole of a freely suspended magnetized needle is the one that points toward the geographical north of the earth4 ,in ,france1 and by some ,english authors1 this pole is called the south one4 ,among electricians of the same country1 what by one is called electro-motive force is by another styled difference of potential1 by a third tension1 and even difference of tension4 ,our confrere ,ruhlmann1 of the ,elektrotechnische ,zeitschrift1 gives a still more remarkable example yet of such confusion4 ,the word polarization1 borrowed from optics1 where it has an unequivocal sense1 serves likewise to designate the development of the counter electro-motive force of galvanic elements1 and also that essentially different condition of badly conducting substances that is brought about by the simultaneous influence of quantities of opposite electricity4 ,in ,germany1 the word induction1 coupled with the word wire1 for example1 according to the formation of compound words in that language1 may also have a double meaning1 and it is by the sense alone of the phrase that we learn whether we have to do with an induced wire or an inducting one4 ,the examples might be multiplied4 ,at its session of ,november #e1 #ahhd1 the ,international ,society of ,electricians1 upon a motion of ,mr4 ,hospitalier1 who had made a communication upon this question1 appointed a committee to study it and report upon it4 ,the ,english ,society of ,electricians likewise took the subject into consideration1 and one of its most active and distinguished members1 ,mr4 ,jamieson1 presented the result of his labors at the ,may session of the society in #ahhe4 ,a discussion arose in which the committee of the ,international ,society of ,electricians was invited to take part4 ,the committee was represented by its secretary1 ,mr4 ,hospitalier1 who expressed himself in about these words3 ,the committee on electric notations presided over by ,mr4 ,blauvelt has finished a part of its task1 that relative to abbreviations1 notations1 and symbols4 ,it will soon take up the second part1 which relates to definitions and agreements4 ,he broadly outlined the committee's ideas as follows3 ,in all physical magnitudes that are made use of1 we have3 7#a7 the physical magnitude itself1 aside from the units that serve to measure it2 7#b7 the ,c4,g4,s4 unit that serves to measure such grandeur 7granted the adoption of the ,c4,g4,s4 system72 7#c7 practical units1 which1 in general1 have a special name for each kind of magnitude1 and are a decimal multiple or sub-multiple of the ,c4,g4,s4 unit1 except for time and angles2 7#d7 finally1 decimal multiples and sub-multiples of these practical units1 that are in current use4 ,the committee likewise decided always to adopt a large capital to designate the physical magnitude2 a small capital to designate the ,c4,g4,s4 unit1 when it has a special name2 a lower case letter for the abbreviation of each practical unit2 and prefixes1 always the same1 for the decimal multiples and sub-multiples of the practical units4 ,thus1 for example1 work would be indicated by the letter ,w 7initial of the word72 the ,c4,g4,s4 unit is the erg1 which would be written without abbreviation1 on account of its being short2 and the practical units would be the kilogrammeter 7kgm71 the grammeter 7gm71 etc4 ,the multiples would be the meg-erg1 the tonne-meter 7t-m71 etc4 ,mr4 ,jamieson's propositions have been in great part approved4 ,some criticisms1 however1 were made during the course of the discussion1 and it is for this reason that the scheme still remains open to improvements4 ,the proposed symbols are as follows3 ,a4--,,practical ,,electric ,,units4 ,total resistance of a circuit4 ,r ,internal resistance of a source of current4 r#a ,resistance of the separate parts of a current4 r#a1 r#b1 etc4 ,specific resistance4 rho #a ohm4 omega #a megohm4 ,omega ,intensity of a current4 ,c ,magnitude of #a ampere4 ,a #a milliampere4 alpha ,electro-motive force4 ,e ,magnitude of #a volt4 v ,capacity4 ,k ,constant of specific induction4 sigma #a farad4 ,phi #a microfarad4 phi ,quantity of electricity4 ,q #a coulomb4 ,c ,electric work 7volt coulomb74 v,c ,electric effect 7volt ampere1 watt in one second74 ,w ,horse power4 ,,hp ,b4--,,magnetism4 ,pole of magnet pointing toward the north4 ,n ,the opposite pole4 ,s ,force of a pole1 quantity of magnetism4 m ,distance of the poles of a magnet4 l ,magnetic moment4 ,m m4l ,intensity of magnetization4 ,j ,intensity of the horizontal component of terrestrial magnetism4 ,h ,c4--,,electric ,,measurements4 ,galvanometer and its resistance4 ,g ,resistance of the shunt of a galvanometer4 s ,battery and its internal resistance4 ,b ,for dynamo machines1 the following designations are proposed3 ,the machine itself4 ,d ,positive terminal4 ,t ,negative terminal4 -,t ,magnet forming the field4 ,,fm ,current indicator 7amperemeter74 ,,am ,tension indicator 7voltameter74 ,,mv ,electro-magnet4 ,,em ,luminous intensity of a lamp1 in candles4 c4p4 ,resistance of the armature4 ,ra ,resistance of the magnet forming the field4 ,rm ,resistance of the external circuit4 ,ro ,intensity in the armature4 ,ca ,intensity in the coils of the magnet4 ,cm ,intensity in the external circuit4 ,ce ,coefficient of self-induction4 ,ls ,coefficient of mutual induction4 ,lm ,a primary battery would be represented as in ,fig4 #a1 and a battery of accumulators as in ,fig4 #b4 ,illustration3 ,,fig4 #a4 ,illustration3 ,,fig4 #b4 ,in order to designate incandescent lamps1 circles would be used1 and stars for arc lamps4 ,a system of incandescent lamps arranged in multiple arc would be represented as in ,fig4 #c4 ,illustration3 ,,fig4 #c4 ,fig4 #d and the formula ,r ,b ,gs_/7,g s7 r would serve for the total resistance1 ,r1 of an electric circuit1 upon giving the letters the significations adopted4 ,illustration3 ,,fig4 #d4 ,such is1 in brief1 the present state of the question4 ,the scientific bodies that have taken hold of it have not as yet furnished a fully co-ordinated work on the subject4 ,let us hope1 however1 that we shall not have to wait long4 ,the question is of as much interest to scientific men as to practical ones4 ,a collection of identical symbols would have the advantage of permitting us to abridge explanations in regard to the signification of terms used in mathematical formulas4 ,a simple examination of a formula would suffice to teach us its contents without the aid of tiresome explanatory matter4 ,but in order that the language shall be precise1 it will be necessary for the words always to represent precise ideas that are universally accepted1 and for their sense not to depend upon the manner of understanding the idea according to their arrangement in the phrase4 ,nothing can be more desirable than that the societies of electricians of all countries shall continue the study of these questions with the desire of coming to a common understanding through a mutual sacrifice of certain preferences and habitudes4--,e4 ,dieudonne1 in ,la ,lumiere ,electrique4 99 99 99 99 99 ,,improved ,,microscopical ,,settling ,,tube4 ,by ,f4 ,,vanderpoel1 of ,newark1 ,new ,jersey4 ,in the ,february number of this ,journal the writer described a new settling tube for urinary deposits which possessed several advantages over the old method with conical test-glass and pipette4 ,for several reasons1 however1 the article was not illustrated1 and it is for the purpose of elucidation by means of illustration1 as well as to bring before the readers of the ,journal two new and improved forms of the tube1 that space in these columns is again sought4 ,the first two of the figures1 #a and #b1 represent the tube as originally devised2 #a denoting the tube with movable cap secured to it by means of a rubber band1 and #b the tube with a ground glass cap and stop cock4 ,the first departure from these forms is shown at #c1 and consists of a conical tube1 as before1 but provided with a perforated stopper1 the side opening in which communicates with a side tube4 ,the perforation in the stopper1 which is easily made by a glass blower1 thus allows the overflow1 when the stopper is inserted into the full tube1 to pass into the side tube4 ,the stopper is then turned so as to cut off the urine in the latter from that in the large tube1 and the latter is thus made tight4 ,after allowing it to remain at rest long enough to permit subsidence of all that will settle1 the stopper is gently turned and a drop taken off the lower end upon a slide1 to be examined at leisure with the microscope4 ,the cap1 ground and fitted upon the lower end1 is put there as a precautionary measure1 as will be seen farther on4 ,illustration3 ,,vanderpoel',s ,,settling ,,tubes4 ,the tube shown at #d is1 we think1 an improvement upon all of the foregoing1 for upon it there is no side tube to break off1 and everything is comprised in a small space4 ,as will be seen by referring to the figure1 there is a slight enlargement in the ground portion of the stopper end of the tube1 this protuberance coming down about one-half the length of the stopper1 which is solid and ground to fit perfectly4 ,the lower half1 however1 is provided with a small longitudinal slit or groove1 the lower end of which communicates with the interior of the tube1 while the upper end just reaches the enlargement in the side of the latter4 ,thus in one position of the stopper there is a communication between the tube and the outer air1 while in all other positions the tube is quite shut4 ,in all these tubes care must be taken to fill them completely with the urine1 and to allow no bubbles of air to remain therein4 ,the first of these settling tubes was made without the ground cap on the lower end1 the latter being inserted into a small test tube for safety4 ,at the suggestion of ,mr4 ,j4,l4 ,smith the test tube was made a part of the apparatus by fitting it 7by grinding7 upon the conical end1 and in its present form it serves to protect the latter from dust and to prevent evaporation of the urine 7or other liquid71 and consequent deposition of salts1 if1 for any reason1 the user should allow the tube to remain suspended for several days4 ,these tubes will be found very useful for collecting and concentrating into a small bulk the sediment contained in any liquid1 whether it be composed of urinary deposits1 diatoms in process of being cleaned1 or any thing of like nature2 and1 as the parts are all of glass1 the strongest acids may be used1 excepting1 of course1 hydrofluoric acid1 without harm to the tubes4--,american ,microscopical ,journal4 99 99 99 99 99 ,continued from ,,supplement1 ,no4 #eid1 page #idia4 ,,climate ,,in ,,its ,,relation ,,to ,,health4 ,by ,g4,v4 ,,poore1 ,m4,d4 ,footnote3 ,three lectures before the ,society of ,arts1 ,london4 ,from the ,journal of the ,society4 ,,lecture ,,iii4 ,,diseases ,,caused ,,by ,,floating ,,matter ,,in ,,the ,,air4 ,the information which modern methods of research have given us with regard to the floating matter in the air is of an importance which cannot be overestimated4 ,that the air is full of organic particles capable of life and growth is now a matter of absolute certainty4 ,it has long been a matter of speculation1 but there is a great difference between a fact and a speculation4 ,an eminent historian has recently deprecated the distinction which is conventionally drawn between science and knowledge1 but1 nevertheless1 such a distinction is useful1 and will continue to be drawn4 ,a man's head may be filled with various things4 ,his inclination may lead him1 for example1 to study archaic myths in the various dialects which first gave them birth2 he may have a fancy for committing to memory the writings of authors on astrology1 or the speculations of ancient philosophers1 from ,aristotle and ,lucretius downward4 ,such a one may have a just claim to be considered a man of learning1 and far be it from me to despise the branches of knowledge toward which his mind has a natural bent4 ,but in so far as his knowledge is a knowledge of fancies rather than facts1 it has no claim to be called science4 ,fancies1 however beautiful1 cannot form a solid basis for action or conduct1 whereas a scientific fact does4 ,it is all very well to suppose that such and such things may be1 but mere possibilities1 or even probabilities1 do not breed a living faith4 ,they often foster schism1 and give rise to disunited or opposed action on the part of those who think that such and such things may not be4 ,when1 however1 a fancy or a speculation becomes a fact which is capable of demonstration1 its universal acceptance is only a matter of time1 and the man who neglects such facts in regulating his actions or conduct is rightly regarded as insane all the world over4 ,the influence of micro-organisms on disease is emerging more and more1 day by day1 from the regions of uncertainty1 and what once were the speculations of the few are now the accepted facts of the majority4 ,miquel's experiments show very clearly that the number of microbes in the air corresponds with tolerable closeness to the density of population4 ,from the ,alpine solitudes of the ,bernese ,oberland to the crowded ward of a ,parisian hospital1 we have a constantly ascending ratio of microbes in the air1 from zero to #bh1jjj per cubic meter4 ,their complete absence on the ,alps is mainly due to the absence of productive foci4 ,organic matter capable of nourishing microbes is rare1 and the dryness and cold prevent any manifestation of vitality or increase4 ,whence come the large number of microbes in the crowded places and in hospitals8 ,every individual1 even in health1 is a productive focus for microbes2 they are found in the breath1 and flourish luxuriantly in the mouth of those especially who are negligent in the use of the tooth brush4 ,when we speak of flourishing luxuriantly1 what do we mean8 ,simply that these microbes1 under favorable circumstances1 increase by simple division1 and that one becomes about #af1jjj1jjj in twenty-four hours4 ,the breath1 even of healthy persons1 contains ammonia and organic matter which we can smell4 ,when the moisture of the breath is condensed and collected1 it will putrefy4 ,every drop of condensed moisture that forms on the walls of a crowded room is potentially a productive focus for microbes4 ,every deposit of dirt on persons1 clothing1 or furniture is also a productive focus1 and production is fostered in close apartments by the warmth and moisture of the place4 ,in hospitals productive foci are more numerous than in ordinary dwellings4 ,if microbes are present in the breath of ordinary individuals1 what can we expect in the breath of those whose lungs are rotten with tubercular disease8 ,then we have the collections of expectorated matter and of other organic secretions1 which all serve as productive foci4 ,every wound and sore1 when antiseptic precautions are not used1 becomes a most active and dangerous focus1 and every patient suffering from an infective disease is probably a focus for the production of infective particles4 ,when we consider1 also1 that hospital wards are occupied day and night1 and continuously for weeks1 it is not to be wondered at that microbes are abundant therein4 ,i want especially to dwell upon the fact that foci1 and probably productive foci1 may exist outside the body4 ,it is highly probable1 judging from the results of experiments1 that every collection of putrescible matter is potentially a productive focus of microbes4 ,the thought1 of a pit or sewer filled with excremental matters mixed with water1 seething and bubbling in its dark warm atmosphere1 and communicating directly 7with or without the intervention of that treacherous machine called a trap7 with a house1 is enough to make one shudder1 and the long bills of mortality already chargeable to this arrangement tell us that if we shudder we do not do so without cause4 ,as an instance of the way in which dangers may work in unsuspected ways1 ,i may mention the fact that ,emmerich1 in examining the soil beneath a ward of a hospital at ,amberg1 discovered therein the peculiar bacillus which causes pneumonia1 and which had probably been the cause of an outbreak of pneumonia that had occurred in that very ward4 ,the importance of ,dutch cleanliness in our houses1 and the abolition of all collections of putrescible matter in and around our houses1 is abundantly evident4 ,it will not be without profit to examine some well-known facts1 by the aids of the additional light which has been thrown upon them by the study of the microbes which are in the media around us4 ,there is no better known cause of a high death rate than overcrowding4 ,overcrowding increases the death rate from infectious diseases1 especially such as whooping cough1 measles1 scarlet fever1 diphtheria1 small-pox1 and typhus4 ,the infection of all these diseases is communicable through the air1 and where there is overcrowding1 the chance of being infected by infective particles1 given off by the breath or skin1 is of course very great4 ,where there is overcrowding1 the collections of putrescible filth are multiplied1 and with them probably the productive foci of infective particles4 ,tubercular disease1 common sore throat1 chicken-pox1 and mumps1 are also among the diseases which are increased by overcrowding4 ,to come to details which are more specific1 let us consider the case of some diseases which are definitely caused by floating matter in the air4 ,first1 let us take one which is apparently attributable to pollen4 ,,hay ,,fever4 ,among diseases which are undoubtedly caused by floating matter in the air must be reckoned the well-known malady hay fever1 which is a veritable scourge during the summer months to a certain percentage of persons1 who have1 probably1 a peculiarly sensitive organization to begin with1 and are1 in a scientific sense1 irritable4 ,this disease has been most thoroughly and laboriously investigated by ,mr4 ,charles ,blackley1 of ,manchester1 who1 being himself a martyr to hay fever1 spent ten years in investigating the subject1 and published the result in #ahgc1 in a small work entitled ,experimental ,researches on the ,causes and ,nature of ,catarrhus aestivus 7hay fever or hay asthma74 ,mr4 ,blackley had little difficulty in determining that the cause of his trouble was the pollen of grasses and flowers1 and his investigations showed that the pollen of some plants was far more irritating than the pollen of others4 ,the pollen of rye1 for example1 produced very severe symptoms of catarrh and asthma1 when inhaled by the nose or mouth4 ,mr4 ,blackley came to the conclusion that the action of the pollen was partly chemical and partly mechanical1 and that the full effect was not produced until the outer envelope burst and allowed of the escape of the granular contents4 ,having satisfied himself that pollen was capable of producing all the symptoms of hay fever1 ,mr4 ,blackley next sought to determine1 by a series of experiments1 the quantity of pollen found floating in the atmosphere during the prevalence of hay fever1 and its relation to the intensity of the symptoms4 ,the amount of pollen was determined by exposing slips of glass1 each having an area of a square centimeter1 and coated with a sticky mixture of glycerine1 water1 proof spirit1 and a little carbolic acid4 ,mr4 ,blackley gives two tables1 showing the average number of pollen grains collected in twenty-four hours on one square of glass1 between ,may #bh and ,august #ba1 in both a rural and an urban position4 ,the maximum both in town and country was reached on ,june #bh1 when in the town #aje pollen grains were deposited1 and in the country #hhj grains4 ,the number of grains deposited was found to vary much1 falling almost to zero during heavy rain and rising to a maximum if the rain were followed by bright sunshine4 ,mr4 ,blackley found that the severity of his own symptoms closely corresponded to the number of pollen grains deposited on his glasses4 ,mr4 ,blackley devised some very ingenious experiments to determine the number of grains floating in the air at different altitudes4 ,the experiments were conducted by means of a kite1 to which the slips of glass were attached1 fixed in an ingenious apparatus1 by means of which the surface of the glass was kept covered until a considerable altitude had been reached4 ,mr4 ,blackley's first experiment gave as a result that #ajd pollen grains were deposited in the glass attached to the kite1 while only #aj were deposited on a glass near the ground4 ,this experiment was repeated4 ,again and again1 and always with the same result1 there was more pollen in the upper strata of the air than in the lower4 ,a very interesting experiment was performed at ,filey1 in ,june1 #ahgj4 ,a breeze was blowing from the sea1 and had been blowing for #ab or #ae hours4 ,mr4 ,blackley flew his kite to an elevation of #a1jjj feet4 ,the glass attached to the kite was exposed for three hours1 and on it there were #hj grains of pollen1 whereas a similar glass1 exposed at the margin of the water1 showed no pollen nor any organic form4 ,whence came this pollen collected on the upper glass8 ,probably from ,holland or ,denmark4 ,possibly from some point nearer the center of ,europe4 ,,potato ,,disease4 ,a study of the terrible disease which so often attacks the potato crop in this country will serve1 ,i think1 to bring forcibly before you certain untoward conditions which may be called climatic1 and which are attributable to fungoid spores in the air4 ,with the potato disease you are all1 probably1 more or less practically acquainted4 ,when summer is at its height1 and when the gardeners and farmers are all looking anxiously to the progress of their crops1 how often have we heard the congratulatory remark of ,how well and strong those potatoes look6 ,such a remark is most common at the end of ,july or the beginning of ,august1 when the green part1 or haulm1 of the plant is looking its best1 and when the rows of potatoes1 with their elegant rich foliage and bunches of blossom1 have an appearance which would almost merit their admission to the flower border4 ,the same evening1 it may be1 there comes a prolonged thunder storm1 followed by a period of hot1 close1 moist1 muggy weather4 ,four-and-twenty hours later1 the hapless gardener notices that certain of his potato plants have dark spots upon some of their leaves4 ,this1 he knows too well1 is the plague spot1 and if he examine his plants carefully1 he will perhaps find that there is scarcely a plant which is not spotted4 ,if the thunder shower which we have imagined be followed by a long period of drought1 the plague may be stayed and the potatoes saved2 but if the damp weather continue1 the number of spotted leaves among the potatoes increases day by day1 until the spotted leaves are the majority2 and then the haulm dies1 gets slimy1 and emits a characteristic odor2 and it will be found that the tubers beneath the soil are but half developed1 and impregnated with the disease to an extent which destroys their value4 ,now1 the essential cause of the potato disease is perfectly well understood4 ,it is parasitical1 the parasite being a fungus1 the ,peronospora infestans1 which grows at the expense of the leaves1 stems1 and tubers of the plant until it destroys their vitality4 ,if a diseased potato leaf be examined with the naked eye1 it will be seen that1 on the upper surface1 there is an irregular brownish black spot1 and if the under surface of the leaf be looked at carefully1 the brown spot is also visible1 but it will be seen to be covered with a very faint white bloom1 due to the growth of the fungus from the microscopic openings or stomata1 which exist in large numbers on the under surface of most green leaves4 ,the microscope shows this bloom to be due to the protrusion of the fungus in the manner stated1 and on the free ends of the minute branches are developed tiny egg shaped vessels1 called conidia1 in which are developed countless spores1 each one of which is theoretically capable of infecting neighboring plants4 ,now1 it is right to say that1 with respect to the mode of spread of the disease1 scientific men are not quite agreed4 ,all admit that it may be conveyed by contact1 that one leaf may infect its neighbors1 and that birds1 flies1 rabbits1 and other ground game may carry the disease from one plant to another and from one crop to another4 ,this is insufficient to account for the sudden onset and the wide extent of potato epidemics1 which usually attack whole districts at one fell swoop4 ,some of those best qualified to judge believe that the spores are carried through the air1 and ,i am myself inclined to trust in the opinion expressed by ,mr4 ,william ,carruthers1 ,f4,r4,s41 before the select committee on the potato crop1 in #ahhj4 ,mr4 ,carruthers' great scientific attainments1 and his position as the head of the botanical department of the ,british ,museum1 and as the consulting naturalist of the ,royal ,agricultural ,society1 at least demand that his opinion should be received with the greatest respect and consideration4 ,mr4 ,carruthers said 7report on the potato crop1 presented to the ,house of ,commons1 ,july #i1 #ahhj1 question #adc et seq473 ,the disease1 ,i believe1 did not exist at all in ,europe before #ahdd4444 ,many diseases had been observed2 many injuries to potatoes had been observed and carefully described before #ahdd2 but this particular disease had not4 ,it is due to a species of plant1 and although that species is small1 it is as easily separated from allied plants as species of flowering plants can be separated from each other4 ,this plant was known in ,south ,america before it made its appearance in this country4 ,it has been traced from ,south ,america to ,north ,america1 and to ,australia1 and it made its first appearance in ,europe in ,belgium1 in #ahdd1 and within a very few days after it appeared in ,belgium1 it was noticed in the ,isle of ,wight1 and then within almost a few hours after that it spread over the whole of the south of ,england and over ,scotland4444 ,when the disease begins to make its appearance1 the fungus produces these large oblong bodies 7conidia71 and the question is how these bodies are spread1 and the disease scattered4444 ,i believe that these bodies1 which are produced in immense quantities1 and very speedily1 within a few hours after the disease attacks the potato1 are floating in the atmosphere1 and are easily transplanted by the wind all over the country4 ,i believe this is the explanation of the spread of the disease in #ahdd1 when it made its appearance in ,belgium4 ,the spores produced in myriads were brought over in the wind1 and first attacked the potato crops in the ,isle of ,wight1 and then spread over the south of ,england4 ,the course of the disease is clearly traced from the south of ,england toward the midland counties1 and all over the island1 and into ,scotland and ,ireland4 ,it was a progress northward4444 ,this plant1 the ,peronospora infestans1 will only grow on the ,solanum tuberosum1 that is1 the cultivated potato4444 ,just as plants of higher organization choose their soils1 some growing in the water and some on land1 so the ,peronospora infestans chooses its host plant2 and its soil is this species1 the ,solatium tuberosum4 ,it will not grow if it falls on the leaves of the oak or the beech1 or on grass1 because that is not its soil1 so to speak4 ,now1 the process of growth is simply this3 ,when the conidia fall on the leaf1 they remain there perfectly innocent and harmless unless they get a supply of water to enable them to germinate4444 ,the disease makes its appearance in the end of ,july or the beginning of ,august1 when we have1 generally1 very hot weather4 ,the temperature of the atmosphere is very high1 and we have heavy showers of rain4 ,the warmth and moisture are1 in fact1 the conditions necessary for the germination of the conidia4 ,their contents 7zoospores7 are liberated1 and quickly grow in the leaf1 and soon permeate every tissue of the plant4 ,it was clearly established before the committee that not all potatoes were equally liable to the disease4 ,the liability depends upon strength of constitution4 ,it is well known that potatoes are usually1 almost invariably1 propagated by sets1 that is1 by planting tubers1 or portions of tubers1 and this method of propagation is analogous to the propagation of other forms of plants by means of cuttings4 ,when potatoes are raised from seed1 it is found that some of the seedlings present a strength of constitution which enables them to resist the disease for some years1 even though the subsequent propagation of the seedling is entirely from sets4 ,the raising of seedling potatoes is a tedious process1 but the patience of the grower is often rewarded by success1 and ,i may allude to the fact that the so-called ,champion potato1 raised from seed in the first instance by ,mr4 ,nicoll1 in ,forfarshire1 and since propagated all over the country1 has enjoyed1 deservedly as it would appear1 a great reputation as a disease-resisting potato2 but all who have a practical knowledge of potato growing seem agreed that we cannot expect its disease-resisting quality to last at most more than twenty years from its first introduction 7in #ahgg71 and that in time the constitution of the ,champion will deteriorate1 and it will become a prey to disease4 ,there is some evidence to show1 also1 that the constitution of the potato may be materially influenced by good or bad culture4 ,damp soils1 insufficient or badly selected manures1 the selection of ill developed potatoes for seed1 and the overcrowding of the sets in the soil1 all seem to act as causes which predispose the potatoes to the attacks of the parasite4 ,strong potatoes resist disease1 just as strong children will2 while weak potatoes1 equally with weak children1 are liable to succumb to epidemic influences4 ,the following account of some exact experiments carried out by ,mr4 ,george ,murray1 of the ,botanical ,department of the ,british ,museum1 seems to show that ,mr4 ,carruthers' theory as to the diffusion of conidia through the air is something more than a speculation3 ,in the middle of ,august1 #ahgf1 says ,mr4 ,murray1 ,i instituted the following experiments1 with the object of determining the mode of diffusion of the conidia of ,peronospora infestans4 ,the method of procedure was to expose on the lee side of a field of potatoes1 of which only about two per cent1 were diseased1 ordinary microscopic slides1 measuring two inches long by one inch broad1 coated on the exposed surface with a thin layer of glycerine1 to which objects alighting would adhere1 and in which1 if of the nature of conidia1 they would be preserved4 ,these slides were placed on the projecting stones of a dry stone wall which surrounded the field1 and was at least five yards from the nearest potato plant4 ,during the five days and nights of the experiment1 a gentle wind blew1 and the weather was1 on the whole1 dry and clear4 ,every morning1 about nine o'clock1 ,i placed fourteen slides on the lee side of the field1 and every evening1 about seven o'clock1 ,i removed them1 and placed others till the following morning at nine o'clock4 ,the fourteen slides exposed during the day1 when examined in the evening1 showed 7among other objects73 ,on the first day4 #ae conidia4 second day4 #ag third day4 #bg fourth day4 #d fifth day4 #i ,on none of the five nights did a single conidium alight on the slides4 ,this seemed to me to prove that during the day the conidia1 through the dryness of the atmosphere and the shaking of the leaves1 became detatched and wafted by the air2 while during the night the moisture 7in the form of dew1 and on one occasion of a slight and gently falling shower7 prevented the drying of the conidia1 and thus rendered them less easy of detachment4 ,i determined the nature of the conidia 7#a7 by comparing them with authentic conidia directly removed from diseased plants2 7#b7 by there being attached to some of them portions of the characteristic conidiaphores2 and 7#c7 by cultivating them in a moist chamber1 the result of which was1 that five conidia1 not having been immersed in the glycerine1 retained their vitality1 which they showed by bursting and producing zoospores in the manner characteristic of ,peronospora infestans4 ,,influenza4 ,let us look at another disease by the light of recent knowledge1 viz41 the epidemic influenza1 concerning which ,i remember hearing much talk1 as a child1 in #ahdg-dh4 ,there has been no epidemic of this disease in the ,british ,isles since #ahdg1 but we may judge of its serious nature from the computation of ,peacock that in ,london alone #bej1jjj persons were stricken down with it in the space of a few days4 ,it is characteristic of this disease that it invades a whole city1 or even a whole country1 at one fell swoop1 resembling in its sudden onset and its extent the potato disease which we have been considering4 ,the mode of its spreading forbids us to attribute it1 at least in any material degree1 although it may be partially so1 to contagion in the ordinary sense1 i4e41 contagion passing from person to person along the lines of human intercourse4 ,it forbids us also to look at community of water supply or food1 or the peculiarities of soil1 for the source of the disease virus4 ,we look1 naturally1 to some atmospheric condition for the explanation4 ,that the atmosphere is the source of the virus is made more likely from the fact that the disease has broken out on board ship in a remarkable way4 ,in #aghb1 there was an epidemic1 and on ,may #b in that year1 says ,sir ,thomas ,watson-- ,admiral ,kempenfelt sailed from ,spithead with a squadron1 of which the ,goliah was one4 ,the crew of that vessel were attacked with influenza on ,may #bi1 and the rest were at different times affected2 and so many of the men were rendered incapable of duty by this prevailing sickness1 that the whole squadron was obliged to return into port about the second week in ,june1 not having had communication with any port1 but having cruised solely between ,brest and the ,lizard4 ,in the beginning of the same month another large squadron sailed1 all in perfect health1 under ,lord ,howe's command1 for the ,dutch coast4 ,toward the end of the month1 just at the time1 therefore1 when the ,goliah became full of the disease1 it appeared in the ,rippon1 the ,princess ,amelia1 and other ships of the last mentioned fleet1 although there had been no intercourse with the land4 ,similar events were noticed during the epidemic of #ahcc3 ,on ,april #c1 #ahcc1 the very day on which ,i saw the first two cases that ,i did see of influenza--all ,london being smitten with it on that and the following day--the ,stag was coming up the ,channel1 and arrived at two o'clock off ,berry ,head on the coast of ,devonshire1 all on board being at that time well4 ,in half an hour afterward1 the breeze being easterly and blowing off the land1 #dj men were down with the influenza1 by six o'clock the number was increased to #fj1 and by two o'clock the next day to #afj4 ,on the self-same evening a regiment on duty at ,portsmouth was in a perfectly healthy state1 but by the next morning so many of the soldiers of the regiment were affected by the influenza that the garrison duty could not be performed by it4 ,after reviewing the various hypotheses which had been put forward to account for the disease1 sudden thaws1 fogs1 particular winds1 swarms of insects1 electrical conditions1 ozone1 ,sir ,thomas ,watson goes on to say3 ,another hypothesis1 more fanciful perhaps at first sight than these1 yet quite as easily accommodated to the known facts of the distemper1 attributes it to the presence of innumerable minute substances1 endowed with vegetable or with animal life1 and developed in unusual abundance under specific states of the atmosphere in which they float1 and by which they are carried hither and thither4 ,this hypothesis has certainly more facts in support of it now than it had when ,sir ,thomas ,watson gave utterance to it in #ahcg4 ,and when another epidemic of influenza occurs1 we may look with some confidence to having the hypothesis either refuted or confirmed by those engaged in the systematic study of atmospheric bacteria4 ,among curious facts in connection with influenza1 quoted by ,watson1 is the following3 ,during the raging of one epidemic1 #cjj women engaged in coal dredging at ,newcastle1 and wading all day in the sea1 escaped the complaint4 ,reading this1 the mind naturally turns to ,dr4 ,blackley's glass slide exposed on the shore at ,filey1 and upon which no pollen was deposited1 while eighty pollen grains were deposited on a glass at a higher elevation4 ,,small-,,pox4 ,let us next inquire into the evidence regarding the conveyence of small-pox through the air4 ,in the supplement to the ,tenth ,report of the ,local ,government ,board for #ahhj-ha 7c4 #c1bij7 is a report by ,mr4 ,w4,h4 ,power on the influence of the ,fulham1 ,hospital 7for small-pox7 on the neighborhood surrounding it4 ,mr4 ,power investigated the incidence of small-pox on the neighborhood1 both before and after the establishment of the hospital4 ,he found that1 in the year included between ,march1 #ahgf1 and ,march1 #ahgg1 before the establishment of the hospital1 the incidence of small-pox on houses in ,chelsea1 ,fulham and ,kensington amounted to #j4da per cent4 7i4e41 that one house out of every #bdd was attacked by small-pox in the ordinary way71 and that the area inclosed by a circle having a radius of one mile round the spot where the hospital was subsequently established 7called in the report the special area7 was1 as a matter of fact1 rather more free from small-pox than the rest of the district4 ,after the establishment of the hospital in ,march1 #ahgg1 the amount of small-pox in the special area round the hospital very notably increased1 as is shown by the table by ,mr4 ,power1 given below4 ,this table shows conclusively that the houses nearest the hospital were in the greatest danger of small-pox4 ,it might naturally be supposed that the excessive incidence of the disease upon the houses nearest to the hospital was due to business traffic between the hospital and the dwellers in the neighborhood1 and ,mr4 ,power admits that he started on his investigation with this belief1 but with the prosecution of his work he found such a theory untenable4 ,,admissions ,,of ,,acute ,,small-,,pox ,,to ,,fulham ,,hospital1 ,,and ,,incidence ,,of ,,small-,,pox ,,upon ,,houses ,,in ,,several ,,divisions ,,of ,,the ,,special ,,area ,,during ,,five ,,epidemic ,,periods4 ---------------------------------------- ------------------------------------ ,incidence on every #ajj houses within the special area and its divisions4 ,cases of,the epidemic periods ---------------------------------------- ---- acute since opening ,on total,on small ,on first ,on second,on third small- of hospital4 special circle1 ring1 ring1 ring1 pox4 area4 #j- mile4- mile4- mile4-#a mile4 ---------------------------------------- --------------------------------- #cbg ,march-,december #ahgg #a4aj #c4dg #a4cg #a4bg #j4cf #gad ,january- ,september1 #ahgh #a4hj #d4fb #b4ee #a4hd #j4fg #fgi ,september #ahgh- ,october #ahgi #a4fh #d4dj #b4fc #a4di #j4fd #bib ,october1 #ahgi- ,december1 #ahhj #j4eh #a4he #a4jf #j4cj #j4bh #eae ,december #ahhj- ,april #ahha #a4ba #b4jj #a4ed #a4be #j4fa ---------------------------------------- --------------------------------- #b1ebg ,five periods #f4cg #af4cd #i4ae #f4ae #b4ef ---------------------------------------- --------------------------------- ,now1 the source of infection in cases of small-pox is often more easy to find than in cases of some other forms of infectious disease1 and mainly for two reasons3 #a4 ,that the onset of small-pox is usually sudden and striking1 such as is not likely to escape observation4 #b4 ,that the so-called incubative period is very definite and regular1 being just a fortnight from infection to eruption4 ,the old experiments of inoculation practiced on our forefathers have taught us that from inoculation to the first appearance of the rash is just twelve days4 ,given a case of small-pox1 then one has only to go carefully over the doings and movements of the patient on the days about a fortnight preceding in order to succeed very often in finding the source of infection4 ,in the fortnight ending ,february #e1 #ahha1 forty-one houses were attacked by small-pox in the special mile circle round the hospital1 and in this limited outbreak it was found1 as previously1 that the severity of incidence bore an exact inverse proportion to the distance from the hospital4 ,the greater part of these were attacked in the five days ,january #bf-cj1 #ahha1 and in seeking for the source of infection of these cases1 special attention was directed to the time about a fortnight previous viz41 ,january #ab-ag1 #ahha4 ,the comings and goings of all who had been directly connected with the hospital 7ambulances1 visitors1 patients1 staff1 nurses1 etc47 were especially inquired into1 but with an almost negative result1 and ,mr4 ,power was reluctantly forced to the conclusion that small-pox poison had been disseminated through the air4 ,during the period when the infection did spread1 the atmospheric conditions were such as would be likely to favor the dissemination of particulate matter4 ,mr4 ,power says3 ,familiar illustration of that conveyance of particulate matter which ,i am here including in the term dissemination is seen1 summer and winter1 in the movements of particles forming mist and fog4 ,the chief of these are1 of course1 water particles1 but these carry gently about with them1 in an unaltered form1 other matters that have been suspended in the atmosphere1 and these other matters1 during the almost absolute stillness attending the formation of dew and hoar frost1 sink earthward1 and may often be recognized after their deposit4 ,as to the capacity of fogs to this end1 no ,londoner needs instruction2 and few persons can have failed to notice the immense distances that odors will travel on the 'air breaths' of a still summer night4 ,and there are reasons which require us to believe particulate matter to be more easy of suspension in an unchanged form during any remarkable calmness of atmosphere4 ,even quite conspicuous objects1 such as cobwebs1 may be held up in the air under such conditions4 ,probably there are few observant persons of rural habits who cannot call to mind one or another still autumn morning1 when from a cloudless1 though perhaps hazy1 sky1 they have noted1 over a wide area1 steady descent of countless spider webs1 many of them well-nigh perfect in all details of their construction4 ,a reference to the meteorological returns issued by the registrar-general shows that on the #abth of ,january1 #ahha1 began a period of severe frost1 characterized by still1 sometimes foggy1 weather1 with occasional light airs from nearly all points of the compass4 ,this state of affairs continued till ,january #ah1 when there was a notable snow storm1 and a gale from the ,e4,n4,e4 ,for four days1 up to and inclusive of ,january #h1 ozone was present in more than its usual amounts4 ,during ,january #i-af1 it was absent4 ,on ,january #ag it reappeared1 and on ,january #ah it was abundant4 ,similar meteorological conditions 7calm and no ozone7 were found to precede previous epidemics4 ,mr4 ,power's report1 with regard to ,fulham1 seems conclusive1 and there is a strong impression that hospitals1 other than ,fulham1 have served as centers of dissemination4 ,in the last lecture ,i gave you the opinion of ,m4 ,bertillon1 of ,paris1 and quoted figures in support of that opinion4 ,it is a fact of some importance to remember that small-pox is one of those diseases which has a peculiar odor1 recognizable by the expert4 ,as to its conveyance for long distances through the air1 there are some curious facts quoted by ,professor ,waterhouse1 of ,cambridge1 ,massachusetts1 in a letter addressed to ,dr4 ,haygarth at the close of the last century4 ,professor ,waterhouse states that at ,boston there was a small-pox hospital on one side of a river1 and opposite it1 #a1ejj yards away1 was a dockyard1 where1 on a certain misty1 foggy day1 with light airs just moving in a direction from the hospital to the dockyard1 ten men were working4 ,twelve days later all but two of these men were down with small-pox1 and the only possible source of infection was the hospital across the river4 7,to be continued47 99 99 99 99 99 ,,sunlight ,,colors4 ,footnote3 ,lecture delivered by ,capt4 ,w4 ,de ,w4 ,abney1 ,r4,e41 ,p4,b4,s41 at the ,royal ,institution1 on ,february #be1 #ahhg4--,nature4 ,by ,capt4 ,w4 ,,de ,w4 ,,abney4 ,sunlight is so intimately woven up with our physical enjoyment of life that it is perhaps not the most uninteresting subject that can be chosen for what is--perhaps somewhat pedantically--termed a ,friday evening discourse4 ,now1 no discourse ought to be be possible without a text on which to hang one's words1 and ,i think ,i found a suitable one when walking with an artist friend from ,south ,kensington ,museum the other day4 ,the sun appeared like a red disk through one of those fogs which the east wind had brought1 and ,i happened to point it out to him4 ,he looked1 and said1 ,why is it that the sun appears so red8 ,being near the railway station1 whither he was bound1 ,i had no time to enter into the subject1 but said if he would come to the ,royal ,institution this evening ,i would endeavor to explain the matter4 ,i am going to redeem that promise1 and to devote at all events a portion of the time allotted to me in answering the question why the sun appears red in a fog4 ,i must first of all appeal to what every one who frequents this theater is so accustomed1 viz41 the spectrum4 ,i am going not to put it in the large and splendid stripe of the most gorgeous colors before you1 with which you are so well acquainted1 but my spectrum will take a more modest form of purer colors1 some twelve inches in length4 ,i would ask you to notice which color is most luminous4 ,i think that no one will dispute that in the yellow we have the most intense luminosity1 and that it fades gradually in the red on the one side and in the violet on the other4 ,this1 then1 may be called a qualitative estimate of relative brightnesses2 but ,i wish now to introduce to you what was novel last year1 a quantitative method of measuring the brightness of any part4 ,before doing this ,i must show you the diagram of the apparatus which ,i shall employ in some of my experiments4 ,illustration3 ,,fig4 #a4--;,,color ,,photometer4 ,,rr are rays 7,fig4 ,i7 coming from the arc light1 or1 if we were using sunlight1 from a heliostat1 and a solar image is formed by a lens1 ,l#a1 on the slit1 ,s#a of the collimator1 ,c4 ,the parallel rays produced by the lens1 ,l#b1 are partially refracted and partially reflected4 ,the former pass through the prisms1 ,p#a,p#b1 and are focused to form a spectrum by a lens1 ,l#c1 on ,d1 a movable ground glass screen4 ,the rays are collected by a lens1 ,l#d1 tilted at an angle as shown1 to form a white image of the near surface of the second prism on ,f4 ,passing a card with a narrow slit1 ,s#b1 cut in it in front of the spectrum1 any color which ,i may require can be isolated4 ,the consequence is that1 instead of the white patch upon the screen1 ,i have a colored patch1 the color of which ,i can alter to any hue lying between the red and the violet4 ,thus1 then1 we are able to get a real patch of very approximately homogeneous light to work with1 and it is with these patches of color that ,i shall have to deal4 ,is there any way of measuring the brightness of these patches8 was a question asked by ,general ,festing and myself4 ,after trying various plans1 we hit upon the method ,i shall now show you1 and if any one works with it he must become fascinated with it on account of its almost childish simplicity--a simplicity1 ,i may remark1 which it took us some months to find out4 ,placing a rod before the screen1 it casts a black shadow surrounded with a colored background4 ,now ,i may cast another shadow from a candle or an incandescence lamp1 and the two shadows are illuminated1 one by the light of the colored patch and the other by the light from an incandescence lamp which ,i am using tonight4 ,shown4 ,now one stripe is evidently too dark4 ,by an arrangement which ,i have of altering the resistance interposed between the battery and the lamp1 ,i can diminish or increase the light from the lamp1 first making the shadow it illuminates too light and then too dark compared with the other shadow1 which is illuminated by the colored light4 ,evidently there is some position in which the shadows are equally luminous4 ,when that point is reached1 ,i can read off the current which is passing through the lamp1 and having previously standardized it for each increment of current1 ,i know what amount of light is given out4 ,this value of the incandescence lamp ,i can use as an ordinate to a curve1 the scale number which marks the position of the color in the spectrum being the abscissa4 ,this can be done for each part of the spectrum1 and so a complete curve can be constructed1 which we call the illumination curve of the spectrum of the light under consideration4 ,now1 when we are working in the laboratory with a steady light1 we may be at ease with this method1 but when we come to working with light such as the sun1 in which there may be constant variation1 owing to passing1 and may be usually imperceptible1 mist1 we are met with a difficulty2 and in order to avoid this1 ,general ,festing and myself substituted another method1 which ,i will now show you4 ,we made the comparison light part of the light we were measuring4 ,light which enters the collimating lens partly passes through the prisms and is partly reflected from the first surface of the prism2 that we utilize1 thus giving a second shadow4 ,the reflected rays from ,p#a fall on ,g1 a silver on glass mirror4 ,they are collected by ,l#e1 and form a white image of the prism also at ,f4 ,the method we can adopt of altering the intensity of the comparison light is by means of rotating sectors1 which can be opened or closed at will1 and the two shadows thus made equally luminous4 ,shown4 ,but although this is an excellent plan for some purposes1 we have found it better to adopt a different method4 ,you will recollect that the brightest part of the spectrum is in the yellow1 and that it falls off in brightness on each side1 so instead of opening and closing the sectors1 they are set at fixed intervals1 and the slit is moved in front of the spectrum1 just making the shadow cast by the reflected beam too dark or too light1 and oscillating between the two till equality is discovered4 ,the scale number is then noted1 and the curve constructed as before4 ,it must be remembered that1 on each side of the yellow1 equality can be established4 ,this method of securing a comparison light is very much better for sun work than any other1 as any variation in the light whose spectrum is to be measured affects the comparison light in the same degree4 ,thus1 suppose ,i interpose an artificial cloud before the slit of the spectroscope1 having adjusted the two shadows1 it will be seen that the passage of steam in front of the slit does not alter the relative intensities2 but this result must be received with caution4 ,the lecturer then proceeded to point out the contrast colors that the shadow of the rod illuminated by white light assumed4 ,i must now make a digression4 ,it must not be assumed that every one has the same sense of color1 otherwise there would be no color blindness4 ,part of the researches of ,general ,festing and myself have been on the subject of color blindness1 and these ,i must briefly refer to4 ,we test all who come by making them match the luminosity of colors with white light1 as ,i have now shown you4 ,and as a color blind person has only two fundamental color perceptions instead of three1 his matching of luminosities is even more accurate than is that made by those whose eyes are normal or nearly normal4 ,it is curious to note how many people are more or less deficient in color perception4 ,some have remarked that it is impossible that they were color blind and would not believe it1 and sometimes we have been staggered at first with the remarkable manner in which they recognized color to which they ultimately proved deficient in perception4 ,for instance1 one gentleman when ,i asked him the name of a red color patch1 said it was sunset color4 ,he then named green and blue correctly1 but when ,i reverted to the red patch he said green4 ,on testing further1 he proved totally deficient in the color perception of red1 and with a brilliant red patch he matched almost a black shadow4 ,the diagram shows you the relative perceptions in the spectrum of this gentleman and myself4 ,there are others who only see three-quarters1 others half1 and others a quarter the amount of red that we see1 while some see none4 ,others see less green and others less violet1 but ,i have met with no one that can see more than myself or ,general ,festing1 whose color perceptions are almost identical4 ,hence we have called our curve of illumination the normal curve4 ,we have tested several eminent artists in this manner1 and about one half of the number have been proved to see only three quarters of the amount of red which we see4 ,it might be thought that this would vitiate their powers of matching color1 but it is not so4 ,they paint what they see2 and although they see less red in a subject1 they see the same deficiency in their pigments2 hence they are correct4 ,if totally deficient1 the case of course would be different4 ,let us carry our experiments a step further1 and see what effect what is known as a turbid medium has upon the illuminating value of different parts of the spectrum4 ,i have here water which has been rendered turbid in a very simple manner4 ,in it has been very cautiously dropped an alcoholic solution of mastic4 ,now mastic is practically insoluble in water1 and directly the alcoholic solution comes in contact with the water it separates out in very fine particles1 which1 from their very fineness1 remain suspended in the water4 ,i propose now to make an experiment with this turbid water4 ,i place a glass cell containing water in front of the slit1 and on the screen ,i throw a patch of blue light4 ,i now change it for turbid water in a cell4 ,this thickness much dims the blue2 with a still greater thickness the blue has almost gone4 ,if ,i measure the intensity of the light at each operation1 ,i shall find that it diminishes according to a certain law1 which is of the same nature as the law of absorption4 ,for instance1 if one inch diminishes the light one half1 the next will diminish it half of that again1 the next half of that again1 while the fourth inch will cause a final diminution of the total light of one sixteenth4 ,if the first inch allows only one quarter of the light1 the next will only allow one sixteenth1 and the fourth inch will only permit #a_/bef part to pass4 ,let us1 however1 take a red patch of light and examine it in the same way4 ,we shall find that1 when the greater thickness of the turbid medium we used when examining the blue patch of light is placed in front of the slit1 much more of this light is allowed to pass than of the blue4 ,if we measure the light1 we shall find that the same law holds good as before1 but that the proportion which passes is invariably greater with the red than the blue4 ,the question then presents itself3 ,is there any connection between the amounts of the red and the blue which pass8 ,lord ,rayleigh1 some years ago1 made a theoretical investigation of the subject4 ,but1 as far as ,i am aware1 no definite experimental proof of the truth of the theory was made till it was tested last year by ,general ,festing and myself4 ,his law was that for any ray1 and through the same thickness1 the light transmitted varied inversely as the fourth power of the wave length4 ,the wave length #f1jjj lies in the red1 and the wave length #d1jjj in the violet4 ,now #f1jjj is to #d1jjj as #c to #b1 and the fourth powers of these wave lengths are as #ha to #af1 or as about #e to #a4 ,if1 then1 the four inches of our turbid medium allowed three quarters of this particular red ray to be transmitted1 they would only allow 77#e1 or rather less than one fourth1 of the blue ray to pass4 ,now1 this law is not like the law of absorption for ordinary absorbing media1 such as colored glass for instance1 because here we have an increased loss of light running from the red to the blue1 and it matters not how the medium is made turbid1 whether by varnish1 suspended sulphur1 or what not4 ,it holds in every case1 so long as the particles which make the medium turbid are small enough4 ,and please to recollect that it matters not in the least whether the medium which is rendered turbid is solid1 liquid1 or air4 ,sulphur is yellow in mass1 and mastic varnish is nearly white1 while tobacco smoke when condensed is black1 and very minute particles of water are colorless2 it matters not what the color is1 the loss of light is always the same4 ,the result is simply due to the scattering of light by fine particles1 such particles being small in dimensions compared with a wave of light4 ,now1 in this trough is suspended #a_/ajjj of a cubic inch of mastic varnish1 and the water in it measures about #ajj cubic inches1 or is #ajj1jjj times more in bulk than the varnish4 ,under a microscope of ordinary power it is impossible to distinguish any particles of varnish2 it looks like a homogeneous fluid1 though we know that mastic will not dissolve in water4 ,now a wave length in the red is about #a_/djjjj of an inch1 and a little calculation will show that these particles are well within the necessary limits4 ,prof4 ,tyndall has delighted audiences here with an exposition of the effect of the scattering of light by small particles in the formation of artificial skies1 and it would be superfluous for me to enter more into that4 ,suffice it to say that when particles are small enough to form the artificial blue sky1 they are fully small enough to obey the above law1 and that even larger particles will suffice4 ,we may sum up by saying that very fine particles scatter more blue light than red light1 and that consequently more red light than blue light passes through a turbid medium1 and that the rays obey the law prescribed by theory4 ,i will exemplify this once more by using the whole spectrum and placing this cell1 which contains hyposulphite of soda in solution in water1 in front of the slit4 ,by dropping in hydrochloric acid1 the sulphur separates out in minute particles2 and you will see that1 as the particles increase in number1 the violet1 blue1 green1 and yellow disappear one by one and only red is left1 and finally the red disappears itself4 ,now let me revert to the question why the sun is red at sunset4 ,those who are lovers of landscape will have often seen on some bright summer's day that the most beautiful effects are those in which the distance is almost of a match to the sky4 ,distant hills1 which when viewed close to are green or brown1 when seen some five or ten miles away appear of a delicate and delicious1 almost of a cobalt1 blue color4 ,now1 what is the cause of this change in color8 ,it is simply that we have a sky formed between us and the distant ranges1 the mere outline of which looms through it4 ,the shadows are softened so as almost to leave no trace1 and we have what artists call an atmospheric effect4 ,if we go into another climate1 such as ,egypt or among the high ,alps1 we usually lose this effect4 ,distant mountains stand out crisp with black shadows1 and the want of atmosphere is much felt4 ,photographs showing these differences were shown4 ,let us ask to what this is due4 ,in such climates as ,england there is always a certain amount of moisture present in the atmosphere1 and this moisture may be present as very minute particles of water--so minute indeed that they will sink down in an atmosphere of normal density--or as vapor4 ,when present as vapor the air is much more transparent1 and it is a common expression to use1 that when distant hills look so close rain may be expected shortly to follow1 since the water is present in a state to precipitate in larger particles4 ,but when present as small particles of water the hills look very distant1 owing to what we may call the haze between us and them4 ,in recent weeks every one has been able to see very multiplied effects of such haze4 ,the ends of long streets1 for instance1 have been scarcely visible1 though the sun may have been shining1 and at night the long vistas of gas lamps have shown light having an increasing redness as they became more distant4 ,every one admits the presence of mist on these occasions1 and this mist must be merely a collection of intangible and very minute particles of suspended water4 ,in a distant landscape we have simply the same or a smaller quantity of street mist occupying1 instead of perhaps #a1jjj yards1 ten times that distance4 ,now ,i would ask1 ,what effect would such a mist have upon the light of the sun which shone through it8 ,it is not in the bounds of present possibility to get outside our atmosphere and measure by the plan ,i have described to you the different illuminating values of the different rays1 but this we can do3 ,first1 we can measure these values at different altitudes of the sun1 and this means measuring the effect on each ray after passing through different thicknesses of the atmosphere1 either at different times of day or at different times of the year1 about the same hour4 ,second1 by taking the instrument up to some such elevation as that to which ,langley took his bolometer at ,mount ,whitney1 and so to leave the densest part of the atmosphere below us4 ,illustration3 ,,fig4 #b4--,,relative ,,luminosities4 ,now1 ,i have adopted both these plans4 ,for more than a year ,i have taken measurements of sunlight in my laboratory at ,south ,kensington1 and ,i have also taken the instrument up to #h1jjj feet high in the ,alps1 and made observations there1 and with a result which is satisfactory in that both sets of observations show that the law which holds with artificially turbid media is under ordinary circumstances obeyed by sunlight in passing through our air3 which is1 you will remember1 that more of the red is transmitted than of the violet1 the amount of each depending on the wave length4 ,the luminosity of the spectrum observed at the ,riffel ,i have used as my standard luminosity1 and compared all others with it4 ,the result for four days you see in the diagram4 ,i have diagrammatically shown the amount of different colors which penetrated on the same days1 taking the ,riffel as ten4 ,it will be seen that on ,december #bc we have really very little violet and less than half the green1 although we have four fifths of the red4 ,the next diagram before you shows the minimum loss of light which ,i have observed for different air thicknesses4 ,on the top we have the calculated intensities of the different rays outside our atmosphere4 ,thus we have that through one atmosphere1 and two1 three1 and four4 ,and you will see what enormous absorption there is in the blue end at four atmospheres4 ,the areas of these curves1 which give the total luminosity of the light1 are #gfa1 #ffb1 #egg1 #ejc1 and #dci2 and if observed as astronomers observe the absorption of light1 by means of stellar observations1 they would have had the values1 #gfa1 #ffd1 #egh1 #ejd1 and #dci--;a very close approximation one to the other4 ,next notice in the diagram that the top of the curve gradually inclines to go to the red end of the spectrum as you get the light transmitted through more and more air1 and ,i should like to show you that this is the case in a laboratory experiment4 ,taking a slide with a wide and long slot in it1 a portion is occupied by a right angled prism1 one of the angles of #de being toward the center of the slot4 ,by sliding this prism in front of the spectrum ,i can deflect outward any portion of the spectrum ,i like1 and by a mirror can reflect it through a second lens1 forming a patch of light on the screen overlapping the patch of light formed by the undeflected rays4 ,if the two patches be exactly equal1 white light is formed4 ,now1 by placing a rod as before in front of the patch1 ,i have two colored stripes in a white field1 and though the background remains of the same intensity of white1 the intensities of the two stripes can be altered by moving the right angled prism through the spectrum4 ,the two stripes are now apparently equally luminous1 and ,i see the point of equality is where the edge of the right angled prism is in the green4 ,placing a narrow cell filled with our turbid medium in front of the slit1 ,i find that the equality is disturbed1 and ,i have to allow more of the yellow to come into the patch formed by the blue end of the spectrum1 and consequently less of it in the red end4 ,i again establish equality4 ,placing a thicker cell in front1 equality is again disturbed1 and ,i have to have less yellow still in the red half1 and more in the blue half4 ,i now remove the cell1 and the inequality of luminosity is still more glaring4 ,this shows1 then1 that the rays of maximum luminosity must travel toward the red as the thickness of the turbid medium is increased4 ,the observations at #h1jjj feet1 here recorded1 were taken on ,september #ae1 at noon1 and of course in latitude #df the sun could not be overhead1 but had to traverse what would be almost exactly equivalent to the atmosphere at sea level4 ,it is much nearer the calculated intensity for no atmosphere intervening than it is for one atmosphere4 ,the explanation of this is easy4 ,the air is denser at sea level than at #h1jjj feet up1 and the lower stratum is more likely to hold small water particles or dust in suspension than is the higher4 ,illustration3 ,,fig4 #c4--,,proportions ,,of ,,transmitted ,,colors4 ,for1 however small the particles may be1 they will have a greater tendency to sink in a rare air than in a denser one1 and less water vapor can be held per cubic foot4 ,looking1 then1 from my laboratory at ,south ,kensington1 we have to look through a proportionately larger quantity of suspended particles than we have at a high altitude when the air thicknesses are the same4 ,and consequently the absorption is proportionately greater at sea level that at #h1jjj feet high4 ,this leads us to the fact that the real intensity of illumination of the different rays outside the atmosphere is greater than it is calculated from observations near sea level4 ,prof4 ,langley1 in this theater1 in a remarkable and interesting lecture1 in which he described his journey up ,mount ,whitney to about #ab1jjj feet1 told us that the sun was really blue outside our atmosphere1 and at first blush the amount of extra blue which he deduced to be present in it would1 he thought1 make it so4 ,but though he surmised the result from experiments made with rotating disks of colored paper1 he did not1 ,i think1 try the method of using pure colors1 and consequently1 ,i believe1 slightly exaggerated the blueness which would result4 ,i have taken ,prof4 ,langley's calculations of the increase of intensity for the different rays1 which ,i may say do not quite agree with mine1 and ,i have prepared a mask which ,i can place in the spectrum1 giving the different proportions of each ray as calculated by him1 and this when placed in front of the spectrum will show you that the real color of sunlight outside the atmosphere1 as calculated by ,langley1 can scarcely be called bluish4 ,alongside ,i place a patch of light which is very closely the color of sunlight on a ,july day at noon in ,england4 ,this comparison will enable you to gauge the blueness1 and you will see that it is not very blue1 and1 in fact1 not bluer perceptibly than that we have at the ,riffel1 the color of the sunlight at which place ,i show in a similar way4 ,i have also prepared some screens to show you the value of sunlight after passing through five and ten atmospheres4 ,on an ordinary clear day you will see what a yellowness there is in the color4 ,it seems that after a certain amount of blue is present in white light1 the addition of more makes but little difference in the tint4 ,but these last patches show that the light which passes through the atmosphere when it is feebly charged with particles does not induce the red of the sun as seen through a fog4 ,it only requires more suspended particles in any thickness to induce it4 ,in observations made at the ,riffel1 and at #ad1jjj feet1 ,i have found that it is possible to see far into the ultra-violet1 and to distinguish and measure lines in the sun's spectrum which can ordinarily only be seen by the aid of a fluorescent eye piece or by means of photography4 ,circumstantial evidence tends to show that the burning of the skin1 which always takes place in these high altitudes in sunlight1 is due to the great increase in the ultra-violet rays4 ,it may be remarked that the same kind of burning is effected by the electric arc light1 which is known to be very rich in these rays4 ,again1 to use a homely phrase1 ,you cannot eat your cake and have it4 ,you cannot have a large quantity of blue rays present in your direct sunlight and have a luminous blue sky4 ,the latter must always be light scattered from the former4 ,now1 in the high ,alps you have1 on clear day1 a deep blue-black sky1 very different indeed from the blue sky of ,italy or of ,england2 and as it is the sky which is the chief agent in lighting up the shadows1 not only in those regions do we have dark shadows on account of no intervening--what ,i will call--mist1 but because the sky itself is so little luminous4 ,in an artistic point of view this is important4 ,the warmth of an ,english landscape in sunlight is due to the highest lights being yellowish1 and to the shadows being bluish from the sky light illuminating them4 ,in the high ,alps the high lights are colder1 being bluer1 and the shadows are dark1 and chiefly illuminated by reflected direct sunlight4 ,those who have traveled abroad will know what the effect is4 ,a painting in the ,alps1 at any high elevation1 is rarely pleasing1 although it may be true to nature4 ,it looks cold1 and somewhat harsh and blue4 ,in ,london we are often favored with easterly winds1 and these1 unpleasant in other ways1 are also destructive of that portion of the sunlight which is the most chemically active on living organisms4 ,the sunlight composition of a ,july day may1 by the prevalence of an easterly wind1 be reduced to that of a ,november day1 as ,i have proved by actual measurement4 ,in this case it is not the water particles which act as scatterers1 but the carbon particles from the smoke4 ,knowing1 then1 the cause of the change in the color of sunlight1 we can make an artificial sunset1 in which we have an imitation light passing through increasing thicknesses of air largely charged with water particles4 ,the image of a circular diaphragm placed in front of the electric light was thrown on the screen in imitation of the sun1 and a cell containing hyposulphite of soda placed in the beam4 ,hydrochloric acid was then added2 as the fine particles of sulphur were formed1 the disk of light assumed a yellow tint1 and as the decomposition of the hyposulphite progressed1 it assumed an orange and finally a deep red tint4 ,with this experiment ,i terminate my lecture1 hoping that in some degree ,i have answered the question ,i propounded at the outset--why the sun is red when seen through a fog4 99 99 99 99 99 ,,the ,,wave ,,theory ,,of ,,sound ,,considered4 ,by ,,henry4 ,a4 ,,mott1 ,ph4,d41 ,,ll4,d4 ,before presenting any of the numerous difficulties in the way of accepting the wave theory of sound as correct1 it will be best to briefly represent its teachings1 so that the reader will see that the writer is perfectly familiar with the same4 ,the wave theory of sound starts off with the assumption that the atmosphere is composed of molecules1 and that these supposed molecules are free to vibrate when acted upon by a vibrating body4 ,when a tuning fork1 for example1 is caused to vibrate1 it is assumed that the supposed molecules in front of the advancing fork are crowded closely together1 thus forming a condensation1 and on the retreat of the fork are separated more widely apart1 thus forming a rarefaction4 ,on account of the crowding of the molecules together to form the condensation1 the air is supposed to become more dense and of a higher temperature1 while in the rarefaction the air is supposed to become less dense and of lower temperature2 but the heat of the condensation is supposed to just satisfy the cold of the rarefaction1 in consequence of which the average temperature of the air remains unchanged4 ,the supposed increase of temperature in the condensation is supposed to facilitate the transference of the sound pulse1 in consequence of which1 sound is able to travel at the rate of #a1jie feet a second at #j;,c41 which it would not do if there was no heat generated4 ,in other words1 the supposed increase of temperature is supposed to add #a_/f to the velocity of sound4 ,if the tuning fork be a ,koenig ,c#c fork1 which makes #bef full vibrations in one second1 then there will be #bef sound waves in one second of a length of #ajie_/bef or #d4bc feet1 so that at the end of a second of time from the commencement of the vibration1 the foremost wave would have reached a distance of #a1jie feet1 at #j;,c4 ,the motion of a sound wave must not1 however1 be confounded with the motion of the molecules which at any moment form the wave2 for during its passage every molecule concerned in its transference makes only a small excursion to and fro1 the length of the excursion being the amplitude of vibration1 on which the intensity of the sound depends4 ,taking the same tuning fork mentioned above1 the molecule would take #a_/bef of a second to make a full vibration1 which is the length of time it takes for the pulse to travel the length of the sound wave4 ,for different intensities1 the amplitude of vibration of the molecule is roughly #a_/ej to #a_/ajjjjjj of an inch4 ,that is to say1 in the case of the same tuning fork1 the molecules it causes to vibrate must either travel a distance of #a_/ef or #a_/ajjjjjj of an inch forward and back in the #a_/bef of a second or in one direction in the #a_/eab of a second4 ,i might further state that the pitch of the sound depends on the number of vibrations and the intensity1 as already indicated by the amplitude of stroke--the timbre or quality of the sound depending upon factors which will be clearly set forth as we advance4 ,having now clearly and correctly represented the wave theory of sound1 without touching the physiological effect perceived by means of the ear1 we will proceed to consider it4 ,we must first consider the state in which the supposed molecules exist in the air1 before making progress4 ,the present science teaches that the diameter of the supposed molecules of the air is about #a_/bejjjjjjj of an inch 7,tait72 that the distance between the molecules is about #h_/ajjjjj of an inch2 that the velocity of the molecules is about #a1eab feet a second at #j;,c41 in its free path2 that the number of molecules in a cubic inch at #j;,c4 is #c1eje1eai1hjj1jjj1jjj1jjj or #ce followed by #ag ciphers 7#ce7ag2 and that the number of collisions per second that the molecules make is1 according to ,boltzmann1 for hydrogen1 #ag1gjj1jjj1jjj1 that is to say1 a hydrogen molecule in one second has its course wholly changed over seventeen billion times4 ,assuming seventeen billion or million to be right for the supposed air molecules1 we have a very interesting problem to consider4 ,the wave theory of sound requires1 if we expect to hear sound by means of a ,c#c fork of #bef vibrations1 that the molecules of the air composing the sound wave must not be interfered with in such a way as to prevent them from traveling a distance of at least #a_/ej to #a_/ajjjjjj of an inch forward and back in the #a_/bef of a second4 ,the problem we have to explain is1 how a molecule traveling at the rate of #a1eab feet a second through a mean path of #h_/ajjjjj of an inch1 and colliding seventeen billion or million times a second1 can1 by the vibration of the ,c#c fork1 be made to vibrate so as to have a pendulous motion for #a_/bef of a second and vibrate through a distance of #a_/ej to the #a_/ajjjjjj of an inch without being changed or mar its harmonic motion4 ,it is claimed that the range of sound lies between #af vibrations and #cj1jjj 7about72 in such extreme cases the molecules would require #a_/af and #a_/cjjjj of a second to perform the same journey4 ,it must not be forgotten that a mass moving through a given distance has the power of doing work1 and the amount of energy it will exercise will depend on its velocity4 ,now1 a molecule of oxygen or nitrogen1 according to modern science1 is a mass #a_/bejjjjjjj of an inch in diameter1 and an oxygen molecule has been calculated to weigh #j4jjjjjjjjedjdd ounce4 ,taking this weight traveling with a velocity of #a1eab feet a second through an average distance of #h_/ajjjjj of an inch1 the battering power or momentum it would have can be shown to be in round numbers capable of moving #a_/bjjjjj of an ounce4 ,now1 when the ,c#c tuning fork has been vibrating for some time1 but still sounding audibly1 ,prof4 ,carter determined that its amplitude of stroke was only the #a_/agjjj of an inch1 or its velocity of motion was at the rate of #a_/cc of an inch in one second1 or one inch in #cc seconds 7over half a minute71 or less than one foot in one hour4 ,assuming one prong to weigh two ounces1 we have a two-ounce mass moving #a_/agjjj of an inch with a velocity of #a_/cc of an inch in one second4 ,the prong1 then1 has a momentum or can exercise an amount of energy equivalent to #a_/bjj of an ounce1 or can overcome the momentum of #a1jjj molecules4 ,it would be difficult to discover not only how a locust can expend sufficient energy to impart to molecules of the air1 so as to set them in a forced vibration1 and thus enable a pulse of the energy imparted to control the motion of the supposed molecules of the air for a mile in all directions1 but also to estimate the amount of energy the locust must expend4 ,according to the wave theory1 a condensation and rarefaction are necessary to constitute a sound wave4 ,surely1 if a condensation is not produced1 there can be no sound wave6 ,we have then no need to consider anything but the condensation or compression of the supposed air molecules1 which will shorten the discussion4 ,the property of mobility of the air and fluidity of water are well known4 ,in the case of water1 which is almost incompressible1 this property is well marked1 and unquestionably would be very nearly the same if water were wholly incompressible4 ,in the case of the air1 it is conceded by ,tyndall1 ,thomson1 ,daniell1 ,helmholtz1 and others that any compression or condensation of the air must be well marked or defined to secure the transmission of a sound pulse4 ,the reason for this is on account of this very property of mobility4 ,tyndall says3 ,the prong of the fork in its swift advancement condenses the air4 ,thomson says3 ,if ,i move my hand vehemently through the air1 ,i produce a condensation4 ,helmholtz says3 ,the pendulum swings from right to left with a uniform motion4 ,near to either end of its path it moves slowly1 and in the middle fast4 ,among sonorous bodies which move in the same way1 only very much faster1 we may mention tuning forks4 ,tyndall says again3 ,when a common pendulum oscillates1 it tends to form a condensation in front and a rarefaction behind4 ,but it is only a tendency2 the motion is so slow1 and the air so elastic1 that it moves away in front before it is sensibly condensed1 and fills the space behind before it can become sensibly dilated4 ,hence waves or pulses are not generated by the pendulum4 ,and finally1 ,daniell says3 ,a vibrating body1 before it can act as a sounding body1 must produce alternate compressions and rarefactions in the air1 and these must be well marked4 ,if1 however1 the vibrating body be so small that at each oscillation the surrounding air has time to flow round it1 there is at every oscillation a local rearrangement--a local flow and reflow of the air2 but the air at a distance is almost wholly unaffected by this4 ,now1 as ,prof4 ,carter has shown by experiment that a tuning fork while still sounding had only an amplitude of swing of #a_/agjjj of an inch1 and only traveled an aggregate distance of #a_/cc of an inch in one second1 or one inch in #cc seconds1 surely such a motion is neither swift1 fast1 nor vehement1 and is unquestionably much slower than the motion of a pendulum4 ,we have only to consider one forward motion of the prong1 and if that motion cannot condense the air1 then no wave can be produced2 for after a prong has advanced and stopped moving 7no matter for how short a time71 if it has not compressed the air1 its return motion 7on the same side7 cannot do anything toward making a compression4 ,if one such motion of #a_/agjjj of an inch in #a_/eab of a second cannot compress the air1 then the remaining motions cannot4 ,there is unquestionably a union limit between mobility and compressibility1 and unless this limit is passed1 mobility holds sway and prevents condensation or compression of the air2 but when this limit is passed by the exercise of sufficient energy1 then compression of the air results4 ,just imagine the finger to be moved through the air at a velocity of one foot in one hour2 is it possible that any scientist who considers the problem in connection with the mobility of the air1 could risk his reputation by saying that the air would be compressed8 ,heretofore it was supposed that a praeong of a tuning fork was traveling fast because it vibrated so many times in a second1 never stopping to think that its velocity of motion was entirely dependent upon the distance it traveled4 ,at the start the prong travels #a_/bj of an inch1 but in a short time1 while still sounding1 the distance is reduced to #a_/agjjj of an inch4 ,while the first motion was quite fast1 about #be inches in a second1 the last motion was only about #a_/cc of an inch in the same time1 and is consequently #hbe times slower motion4 ,the momentum of the prong1 the amount of work it can do1 is likewise proportionately reduced4 ,some seem to imagine1 without thinking1 that the elasticity of the air can add additional energy4 ,this is perfectly erroneous2 for elasticity is a mere property1 which permits a body to be compressed on the application of a force1 and to be dilated by the exercise of the force stored up in it by the compression4 ,no property of the air can impart any energy4 ,if the momentum of a molecule or a series of molecules extending in all directions for a mile is to be overcome so as to control the character of the movements of the molecules1 then sufficient external energy must be applied to accomplish the task3 and when we think that one cubic inch of air contains #c1eje1eai1hjj1jjj1jjj1jjj molecules1 to say nothing about the number in a cubic mile1 which a locust can transmit sound through1 we are naturally compelled to stop and think whether the vibrations of supposed molecules have anything or can have anything to do with the transference of sound through the air4 ,if control was only had of the distance the vibrating molecule travels from its start to the end of its journey1 then only the intensity of the sound would be under subjection2 but if at every infinitesimal instant control was had of its amplitude of swing1 then the character1 timbre1 or quality of the sound is under subjection4 ,it is evident1 then1 that the blows normally given by one molecule to another in their supposed constant bombardment must not be sufficient to alter the character of vibration a molecule set in oscillation by a sounding body must maintain1 to preserve the timbre or quality of the sound in process of transmission2 for if any such alteration should take place1 then1 naturally1 while the pitch1 and perhaps intensity1 might be transmitted1 the quality of the sound would be destroyed4 ,again1 it is certain that no molecule can perform two sets of vibrations1 two separate movements1 at the same time1 any more than it can be in two places at the same time4 ,when a band of music is playing1 the molecule is supposed to make a complex vibration1 a resultant motion of all acting influences1 which the ear is supposed to analyze4 ,it remains for the mathematician to show how a molecule influenced by twenty or more degrees of applied energy1 and twenty or more required number of frequences of vibration at the same time1 can establish a resultant motion which will transmit the required pitch1 intensity1 and timbre of each instrument4 ,when a molecule is acted on by various forces1 a resultant motion is unquestionably produced1 but this would only tend to send the molecule forward and back in one direction1 and1 in fact1 a direction it might have taken in the first place if hit properly4 ,how any resultant can be established as regards the time necessary for the molecule to take so as to complete a full vibration for the note ,c#aa1 which requires #a_/af of a second1 and for other notes up to ,c'''''1 which only requires #a_/dagf of a second1 as when an orchestra is playing1 is certainly beyond human comprehension1 if it is not beyond the transcendental mathematics of the present day4 ,unquestionably1 the able mathematicians ,lord ,rayleigh1 ,stokes1 or ,maxwell1 if the problem was submitted to them1 would start directly to work1 and deduce by so called higher mathematics the required motions the molecules would have to undergo to accomplish this marvelous task--the same as they have established the diameter of the supposed molecules1 their velocity1 distance apart1 and number of bombardments1 without any shadow of positive proof that any such things as molecules exist4 ,as ,s4 ,caunizzana has said3 ,some of the followers of the modern school push their faith to the borders of fanaticism2 they often speak on molecular subjects with as much dogmatic assurance as though they had actually realized the ingenious fiction of ,laplace1 and had constructed a microscope by which they could detect the molecule and count the number of its constituent atoms4 ,speaking of the modern manufacturers of mathematical hypotheses1 ,mattieu ,williams says3 ,it matters not to them how 'wild and visionary1' how utterly gratuitous1 any assumption may be1 it is not unscientific provided it can be vested in formulae and worked out mathematically4 ,these transcendental mathematicians are struggling to carry philosophy back to the era of ,duns ,scotus1 when the greatest triumph of learning was to sophisticate so profoundly an obvious absurdity that no ordinary intellect could refute it4444 ,the close study of pure mathematics1 by directing the mind to processes of calculation rather than to phenomena1 induces that sublime indifference to facts which has characterized the purely mathematical intellect of all ages4 ,tyndall1 however1 states in all frankness1 and without the aid of mathematical considerations1 that when we try to visualize the motions of the air having one thousand separate tones1 to present to the eye of the mind the battling of the pulses1 direct and reverberated1 the imagination retires baffled at the attempt2 and he might have added1 the shallowness and fallacy of the wave theory of sound was made apparent4 ,he1 however1 does express himself as follows3 ,assuredly1 no question of science ever stood so much in need of revision as this of the transmission of sound through the atmosphere4 ,slowly but surely we mastered the question1 and the further we advance1 the more plainly it appeared that our reputed knowledge regarding it was erroneous from beginning to end4 ,until physicists are willing to admit that the physical forces of nature are objective things--actual entities1 and not mere modes of motion--a full and clear comprehension of the phenomena of nature will never be revealed to them4 ,the motion of all bodies1 whether small or great1 is due to the entitative force stored up in them1 and the energy they exercise is in proportion to the stored-up force4 ,tyndall says that heat itself1 its essence and quiddity1 ,,is ,,motion1 ,,and ,,nothing ,,else4 ,surely1 no scientist who considers what motion is can admit such a fallacious statement1 for motion is simply position in space changing2 it is a phenomenon1 the result of the application of entitative force to a body4 ,it is no more an entity than shadow1 which is likewise a phenomenon4 ,motion1 per se1 is nothing and can do nothing in physics4 ,matter and force are the two great entities of the universe--both being objective things4 ,sound1 heat1 light1 electricity1 etc41 are different forms of manifestation of an all-pervading force element--substantial1 yet not material4 99 99 99 99 99 ,,nature4 ,,the ,,relation ,,of ,,tabasheer ,,to ,,mineral ,,substances4 ,mr4 ,thiselton ,dyer has rendered a great service1 not only to botanists1 but also to physicists and mineralogists1 by recalling attention to the very interesting substance known as tabasheer4 ,as he truly states1 very little fresh information has been published on the subject during recent years1 a circumstance for which ,i can only account by the fact that botanists may justly feel some doubt as to whether it belongs to the vegetable kingdom1 while mineralogists seem to have equal ground for hesitation in accepting it as a member of the mineral kingdom4 ,it is very interesting to hear that so able a physiologist as ,prof4 ,cohn intends to investigate the conditions under which living plants separate this substance from their tissues4 ,that unicellular algae1 like the ,diatomaceae1 living in a medium which may contain only one part in #aj1jjj by weight of dissolved silica1 or even less than that amount1 should be able to separate this substance to form their exquisitely ornamented frustules is one of the most striking facts in natural history1 whether we regard it in its physiological or its chemical aspects4 ,sir ,david ,brewster long ago pointed out the remarkable physical characters presented by the curious product of the vegetable world known as tabasheer1 though so far as ,i can find out it has not in recent years received that attention from physicists which the experiments and observations of the great ,scotch philosopher show it to be worthy of4 ,tabasheer seems to stand in the same relation to the mineral kingdom as do ambers and pearls4 ,it is in fact an opal formed under somewhat remarkable and anomalous conditions which we are able to study2 and in this aspect ,i have for some time past been devoting a considerable amount of attention to the minute structure of the substance by making thin sections and examining them under the microscope4 ,it may be as well1 perhaps1 to give a short sketch of the information upon the subject which ,i have up to the present time been able to obtain1 and in this way to call attention to points upon which further research seems to be necessary4 ,from time immemorial tabasheer has enjoyed a very high reputation in ,eastern countries as a drug4 ,its supposed medicinal virtues1 like those of the fossil teeth of ,china and the belemnites 7thunderbolts7 of this country1 seem to have been suggested by the peculiarity of its mode of occurrence4 ,a knowledge of the substance was introduced into ,western ,europe by the ,arabian physicians1 and the name by which the substance is generally known is said to be of ,arabic origin4 ,much of the material which under the name of tabasheer finds its way to ,syria and ,turkey is said1 however1 to be fictitious or adulterated4 ,in #aghh ,dr4 ,patrick ,russell1 ,f4,r4,s41 then resident at ,vizagapatam1 wrote a letter to ,sir ,joseph ,banks in which he gave an account of all the facts which he had been able to collect with respect to this curious substance and its mode of occurrence1 and his interesting letter was published in the ,philosophical ,transactions for #agij 7vol4 lxxx41 p4 #bgc74 ,tabasheer is said to be sometimes found among the ashes of bamboos that have been set on fire 7by mutual friction874 ,ordinarily1 however1 it is sought for by splitting open those bamboo stems which give a rattling sound when shaken4 ,such rattling sounds do not1 however1 afford infallible criteria as to the presence or absence of tabasheer in a bamboo1 for where the quantity is small it is often found to be closely adherent to the bottom and sides of the cavity4 ,tabasheer is by no means found in all stems or in all joints of the same stem of the bamboos4 ,whether certain species produce it in greater abundance than others1 and what is the influence of soil1 situation1 and season upon the production of the substance1 are questions which do not seem as yet to have been accurately investigated4 ,dr4 ,russell found that the bamboos which produce tabasheer often contain a fluid1 usually clear1 transparent1 and colorless or of greenish tint1 but sometimes thicker and of a white color1 and at other times darker and of the consistency of honey4 ,occasionally the thicker varieties were found passing into a solid state1 and forming tabasheer4 ,dr4 ,russell performed the interesting experiment of drawing off the liquid from the bamboo stem and allowing it to stand in stoppered bottles4 ,a whitish1 cottony sediment was formed at the bottom1 with a thin film of the same kind at the top4 ,when the whole was well shaken together and allowed to evaporate1 it left a residue of a whitish brown color resembling the inferior kinds of tabasheer4 ,by splitting up different joints of bamboo ,dr4 ,russell was also able to satisfy himself of the gradual deposition within them of the solid tabasheer by the evaporation of the liquid solvent4 ,in #agia1 ,mr4 ,james ,louis ,macie1 ,f4,r4,s4 7who afterward took the name of ,smithson71 gave an account of his examination of the properties of the specimens of tabasheer sent home by ,dr4 ,russell 7,phil4 ,trans41 vol4 lxxxi41 #agia1 p4 #cfh74 ,these specimens came from ,vellore1 ,hyderabad1 ,masulipatam1 and other localities in ,india4 ,they were submitted to a number of tests which induced ,mr4 ,macie to believe that they consisted principally of silica1 but that before calcination some vegetable matter must have been present4 ,a determination of the specific gravity of the substance by ,mr4 ,macie gave #b4ahh as the result4 ,another determination by ,mr4 ,cavendish gave #b4afi4 ,in this same paper it is stated that a bamboo grown in a hot-house at ,islington gave a rattling noise1 and on being split open by ,sir ,joseph ,banks yielded1 not an ordinary tabasheer1 but a small pebble about the size of half a pea1 externally of a dark brown or black color1 and within of a reddish brown tint4 ,this stone is said to have been so hard as to cut glass1 and to have been in parts of a crystalline structure4 ,its behavior with reagents was found to be different in many respects from that of the ordinary tabasheer2 and it was proved to contain silica and iron4 ,the specimen is referred to in a letter to ,berthollet published in the ,annales de ,chimie for the same year 7,october1 #agia74 ,there may be some doubt as to whether this specimen was really of the nature of tabasheer4 ,if such were the case1 it would seem to have been a tabasheer in which a crystalline structure had begun to be set up4 ,in the year #ahjf1 ,,mm4 ,foureroy and ,vauquelin gave an account of a specimen of tabasheer brought from ,south ,america in #ahjd by ,humboldt and ,bonpland 7,mem4 de l',inst41 vol4 vi41 p4 #chb74 ,it was procured from a species of bamboo growing on the west of ,pichincha1 and is described as being of a milk white color1 in part apparently crystalline in structure1 and in part semi-transparent and gelatinous4 ,it was seen to contain traces of the vegetable structure of the plant from which it had been extracted4 ,on ignition it became black1 and emitted pungent fumes4 ,an analysis of this tabasheer from the ,andes showed that it contained #gj per cent4 of silica and #cj per cent4 of potash1 lime1 and water1 with some organic matter4 ,it would1 perhaps1 be rash to conclude from this single observation that the ,american bamboo produced tabasheer of different composition from that of the ,old ,world2 but the subject is evidently one worthy of careful investigation4 ,it was in the year #ahai that ,sir ,david ,brewster published the first account of his long and important series of observations upon the physical peculiarities of tabasheer 7,phil4 ,trans41 vol4 cix41 #ahai1 p4 #bhc74 ,the specimens which he first examined were obtained from ,india by ,dr4 ,kennedy1 by whom they were given to ,brewster4 ,brewster found the specimens which he examined to be perfectly isotropic1 exercising no influence in depolarizing light4 ,when heated1 however1 it proved to be remarkably phosphorescent4 ,the translucent varieties were found to transmit a yellowish and to reflect a bluish white light--or1 in other words1 to exhibit the phenomenon of opalescence4 ,when tabasheer is slightly wetted1 it becomes white and opaque2 but when thoroughly saturated with water1 perfectly transparent4 ,by preparing prisms of different varieties of tabasheer1 ,brewster proceeded to determine its refractive index1 arriving at the remarkable result that tabasheer has a lower index of refraction than any other known solid or liquid1 and that it actually holds an intermediate place between water and gaseous bodies6 ,this excessively low refractive power ,brewster believes to afford a complete explanation of the extraordinary behavior exhibited by tabasheer when wholly or partially saturated with fluids4 ,a number of interesting experiments were performed by saturating the tabasheer with oils of different refractive powers1 and by heating it in various ways and under different conditions1 and also by introducing carbonaceous matter into the minute pores of the substance by setting fire to paper in which fragments were wrapped4 ,the mean of experiments undertaken by ,mr4 ,james ,jardine1 on behalf of ,brewster1 for determining the specific gravity of tabasheer1 gave as a result #b4bce4 ,from these experiments ,brewster concluded that the space occupied by the pores of the tabasheer is about two and a half times as great as that of the colloid silica itself6 ,from this time forward ,brewster seems to have manifested the keenest interest in all questions connected with the origin and history of a substance possessing such singular physical properties4 ,by the aid of ,mr4 ,swinton1 secretary to the government at ,calcutta1 he formed a large and interesting collection of all the different varieties of tabasheer from various parts of ,india4 ,he also obtained specimens of the bamboo with the tabasheer in situ4 ,in #ahbh he published an interesting paper on ,the ,natural ,history and ,properties of ,tabasheer 7,edinburgh ,journal of ,science1 vol4 viii41 #ahbh1 p4 #bhh71 in which he discussed many of the important problems connected with the origin of the substance4 ,from his inquiries and observations1 ,brewster was led to conclude that tabasheer was only produced in those joints of bamboos which are in an injured1 unhealthy1 or malformed condition1 and that the siliceous fluid only finds its way into the hollow spaces between the joints of the stem when the membrane lining the cavities is destroyed or rent by disease4 ,prof4 ,edward ,turner1 of the ,university of ,london1 undertook an analysis of tabasheer1 the specimens being supplied from ,brewster's collection 7,edinburgh ,journal of ,science1 vol4 viii41 #ahbh1 p4 #cce74 ,his determinations of the specific gravities of different varieties were as follows3 ,chalky tabasheer4 #b4ahi ,translucent tabasheer4 #b4afg ,transparent tabasheer4 #b4afj ,all the varieties lose air and hygroscopic water at #ajj ,c41 and a larger quantity of water and organic matter 7indicated by faint smoke and an empyreumatic odor7 at a red heat4 ,the results obtained were as follows3 ,loss at #ajj ,c4 ,loss at red heat4 ,chalky tabasheer4 #j4hch per cent4 #a4bgg per cent4 ,translucent tabasheer4 #a4fbj #c4hdj ,transparent tabasheer4 #b4daa #d4eah ,dr4 ,turner found the ignited ,indian tabasheer to consist almost entirely of pure silica with a minute quantity of lime and vegetable matter4 ,he failed to find any trace of alkalies in it4 ,in #ahee1 ,guibourt 7,journ4 de ,pharm4 #c1 xxvii41 #ha1 #afa1 #beb2 ,phil4 ,mag1 #d1 x41 #bbi7 analyzed a specimen of tabasheer having a specific gravity of #b4adh4 ,it gave the following result3 ,silica4 #if4id ,potash and lime4 #j4ac ,water4 #b4ic ,organic matter4 trace ,guibourt criticised some of the conclusions arrived at by ,brewster1 and sought to explain the source of the silica by studying the composition of different parts of the bamboo4 ,while the ashes of the wood contained #j4jfab of the whole weight of the wood1 the pith was found to contain #j4ddh per cent41 the inner wood much less1 and the greatest proportion occurred in the external wood4 ,on these determinations ,guibourt founded a theory of the mode of formation of tabasheer based on the suggestion that at certain periods of its growth the bamboo needed less silica than at other times1 and that when not needed1 the silica was carried inward and deposited in the interior4 ,in the year #aheg1 ,d4,w4 ,host van ,tonningen1 of ,buitenzorg1 undertook an investigation of the tabasheer of ,java1 which is known to the natives of that island under the name of singkara 7,naturkundig ,tijdschrift voor ,nederlandsch ,indie1 vol4 xiii41 #aheg1 p4 #cia74 ,the specimens examined were obtained from the ,bambusa apus1 growing in the ,residency of ,bantam4 ,it is described as resembling in appearance the ,indian tabasheers4 ,its analysis gave the following result3 ,silica4 #hf4chg ,iron oxide4 #j4dbd ,lime4 #j4bdd ,potash4 #d4hjf ,organic matter4 #j4ejg ,water4 #g4fcb ------ ,total4 #ajj4jjj ,apart from the question of its singular mode of origin1 however1 and its remarkable and anomalous physical properties1 tabasheer is of much interest to mineralogists and geologists4 ,all the varieties hitherto examined1 with the exception of the peculiar one from the ,andes1 are in composition and physical characters true opals4 ,this is the case with all the ,indian and ,java varieties4 ,they consist essentially of silica in its colloidal form1 the water1 lime1 potash1 and organic matter being as small and variable in amount as in the mineral opals2 and1 as in them1 these substances must be regarded merely as mechanical impurities4 ,the tabasheers must be studied in their relations on the one hand with certain varieties of the natural semi-opals1 hydrophanes1 beekites1 and floatstones1 some of which they closely resemble in their physical characters1 and on the other hand with specimens of artificially deposited colloid silica formed under different conditions4 ,prof4 ,church1 who has so successfully studied the beekites1 informs me that some of those remarkable bodies present singular points of analogy with tabasheer4 ,by the study of thin sections ,i have1 during several years1 been endeavoring to trace the minute structure of some of these substances4 ,in no class of materials is it more necessary to guard one's self against errors of observation arising from changes induced in the substance during the operations which are necessary to the preparation of transparent sections of hard substances4 ,unfortunately1 too1 it is the custom of the natives to prepare the substance for the market by an imperfect calcination1 and hitherto ,i have only been able to study specimens procured in the markets which have been subjected to this process4 ,it is obviously desirable1 before attempting to interpret the structures exhibited1 under the microscope1 to compare the fresh and uncalcined materials with those that have been more or less altered by heat4 ,tabasheer would seem1 from ,brewster's experiments1 to be a very intimate admixture of two and a half parts of air with one part of colloidal silica4 ,the interspaces filled with air appear1 at all events1 in most cases1 to be so minute that they cannot be detected by the highest powers of the microscope which ,i have been able to employ4 ,it is this intimate admixture of a solid with a gas which probably gives rise to the curious and anomalous properties exhibited by this singular substance4 ,the ultra-microscopical vesicles filled with air in all probability give rise to the opalescence which is so marked a property of the substance4 ,their size is such as to scatter and throw back the rays at the blue end of the spectrum and to transmit those at the red end4 ,when the vesicles of the substance are filled with ,canada balsam1 and a thin slice is cut from it1 this opalescence comes out in the most striking manner4 ,very thin sections are of a rich orange yellow by transmitted light1 and a delicate blue tint by reflected light4 ,i do not know of any substance which in such thin films displays such striking opalescence4 ,that the excessively low refractive power of tabasheer is connected with the mechanical admixture of the colloidal silica with air seems to be proved by the experiments of ,brewster1 showing that with increase of density there was an increase in the refractive index from #a4aaa in specimens of the lowest specific gravity to #a4ahb in those of the highest specific gravity4 ,where the surface was hard and dense1 ,brewster found the refractive index to approach that of semi opal4 ,the wonderful thing is that a substance so full of cavities containing gas should nevertheless be transparent4 ,by the kindness of ,mr4 ,f4 ,rutley1 ,f4,g4,s41 ,i am able to supply a drawing taken from one of my sections of tabasheer4 ,the accompanying woodcut gives some idea of the interesting structures exhibited in some sections of tabasheer1 though much of the delicacy and fidelity of the original drawing has been lost in transferring it to the wood4 ,in this particular case1 the faint punctation of the surface may possibly indicate the presence of air vesicles of a size sufficiently great to be visible under the microscope4 ,but in many other instances ,i have failed to detect any such indication1 even with much higher powers4 ,the small ramifying tubules might at first sight be taken for some traces of a vegetable tissue1 but my colleague1 ,dr4 ,scott1 assures me that they do not in the least resemble any tissue found in the bamboo4 ,i have myself no doubt that it is an inorganic structure4 ,it is not improbably analogous to the peculiar ramifying tubules formed in a solution of water glass when a crystal of copper sulphate is suspended in it1 as shown by ,dr4 ,heaton 7,proc4 ,brit4 ,assoc41 #ahfi1 p4 #abg74 ,similar forms also occur on a larger scale in some agates1 and the artificial cells of ,traube may probably be regarded as analogous phenomena4 ,the aggregates of globular bodies seen in the section so greatly resemble the globulites of slags and natural glasses1 and in their arrangement so forcibly recall the structures seen in the well known pitchstone of ,corriegills in ,arran1 that one is tempted to regard them as indicating the beginnings of the development of crystalline structure in the tabasheer4 ,but ,i have good grounds for believing the structure to have a totally different origin4 ,they seem in fact to be the portions of the mass which the fluid ,canada balsam has not succeeded in penetrating4 ,by heating they may be made to grow outward1 and as more balsam is imbibed they gradually diminish1 and finally disappear4 ,i must postpone till a future occasion a discussion of all the structures of this remarkable substance and of the resemblances and differences which they present to the mineral opals on the one hand1 and to those of the opals of animal origin found in sponge spicules1 radiolarians1 and the rocks formed from them1 some of which have recently been admirably investigated by ,dr4 ,g4,j4 ,hinde 7,phil4 ,trans41 #ahhe1 pp4 #dbe-hc74 ,i cannot1 however1 but think that it would be of the greatest service to botanists1 physicists1 and mineralogists alike1 if some resident in ,india would resume the investigations so admirably commenced by ,dr4 ,patrick ,russell nearly a century ago2 and it is in the hope of inducing some one to undertake this task that ,i have put together these notes4 ,there are certain problems with regard to the mode of occurrence of this singular substance which could only be solved by an investigator in the country where it is found4 ,illustration3 ,,section ,,of ,,indian ,,tabasheer1 ,,seen ,,with ,a ,,magnifying ,,power ,,of #bej ,,diameters4 ,most parcels of the commercial tabasheer appear to contain different varieties1 from the white1 opaque1 chalk like forms through the translucent kinds to those that are perfectly transparent4 ,it would be of much interest if the exact relation and modes of origin of these different varieties could be traced4 ,it would also be important to determine if ,brewster was right in his conclusion that the particular internodes of a bamboo which contain tabasheer always have their inner lining tissue rent or injured4 ,the repetition of ,dr4 ,russell's experiment of drawing off the liquids from the joints of bamboos and allowing them to evaporate is also greatly to be desired4 ,my colleague1 ,prof4 ,rucker1 ,f4,r4,s41 has kindly undertaken to re-examine the results arrived at by ,brewster in the light of more recent physical investigations1 and ,i doubt not that some of the curious problems suggested by this very remarkable substance may ere long find a solution4 ,,john ,w4 ,,judd4 99 99 99 99 99 ,,the ,,edible ,,earth ,,of ,,java4 ,in #ahhc ,mr4 ,hekmeyer1 pharmaceutist in chief of the ,dutch ,indies1 exhibited at ,amsterdam some specimens of ,javanese edible earth1 both in a natural state and in the form of various natural objects4 ,a portion of this collection he has placed at our disposal1 and has given us some information regarding its nature1 use1 etc4 ,these clays1 which are eaten not only in ,java1 but also in ,sumatra1 ,new ,caledonia1 ,siberia1 ,guiana1 ,terra del ,fuego1 etc41 are essentially composed of silex1 alumina1 and water in variable proportions1 and are colored with various metallic oxides4 ,they are in amorphous masses1 are unctuous to the touch1 stick to the tongue1 and form a fine1 smooth paste with water4 ,the natives of ,java and ,sumatra prepare them in a peculiar way4 ,they free them of foreign substances1 spread them out in thin sheets1 which they cut into small pieces and parch in an iron saucepan over a coal fire4 ,each of these little cakes1 when shrunken up into a little roll1 looks somewhat like a grayish or reddish fragment of cinnamon bark4 ,the clay is also formed into imitations of various objects4 ,we have tasted this ,javanese dainty1 and we must very humbly confess that we have found nothing attractive in the earthy and slightly empyreumatic taste of this singular food4 ,however1 a sweet and slightly aromatic taste that follows the first impression is an extenuating circumstance4 ,according to the account given by ,labillardiere1 confirmed by the information given by ,mr4 ,hekmeyer1 the figures are often craunched by women and children1 to the latter of whom they serve as dolls1 toys1 and even money-boxes1 as shown by the slits formed in the upper part of the larger objects1 which are usually hollow4 ,we have not sufficient documents to carry us back to the origin of that tradition that would have it that the human form has been given to certain food preparations from remote times4 ,savants will not be slow to see in this a vague relic of the horrible festivities that succeeded human sacrifices among primitive peoples4 ,for want of prisoners and of designated victims1 a symbolic representation would have gradually developed1 and been kept up1 though losing its religious character4 ,we merely call brief attention to this obscure problem1 not having the pretension to solve it4--,revue d',ethnographie4 99 99 99 99 99 ,,the ,,scientific ,,american ,,supplement4 ,,published ,,weekly4 ,terms of ,subscription1 #e a ,year4 ,sent by 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ordinary book pages1 forming1 practically1 a large and splendid ,magazine of ,architecture1 richly adorned with elegant plates in colors and with fine engravings2 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 ,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