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the inlet pipe, and serves to deaden the from the first instrument to the second. shocks. This engine is often made with This last factor for transmission by electwo cylinders, having their cranks at tricity is the exact correlative of the effiright angles. Its efficiency is equal to ciency of the pipe in the case of comfrom 37 to 83 per cent. The other en- pressed air, or of water pressure. It is gine, which is much ess used, is a tur. as useful in the case of electric transmisbine on Girard's system, with a horizon- sion, as of any other method, to be able, tal axis and partial admission, ex- in studying the system, to estimate be. actly resembling in minatnre those forehand what results it is able to which work in the hydraulic factory furnish; and for this purpose it is necesof St. Maur, near Paris. The water sary to calculate exactly the factors is introduced by means of a distributor, which compose the efficiency. In order which is fitted in the interior of the to obtain this desirable knowledge, the turbine chamber, and occupies a certain author considers that the three following portion of its circumference. This tur. points should form the aim of experibine has a lower efficiency than Schmid's mentalists: (1) The determination of machine, and is less suitable for high the efficiency K of the principal kinds of pressures; but it possesses this advant magneto-electric, or dynamo-electric maage over it—that by regulating the chines working as generators. (2) The amount of opening of the distributor, determination of the efficiency K, of the and consequently the quantity of water same machines working as motors. (3) admitted, the force can be altered with. The determination of the law according out altering the velocity of rotation. Its to which the magnetism of the cores of efficiency varies between 35 and 68 per these machines varies with the intensity cent. The transmission of power by of the current. The author added that electricity was considered last of all. he would gladly have concluded this The author stated nothing new on this paper with a comparison of the effisubject. He gave a table by Mr. Hagen- ciencies of the four systems which have bach, which promised to be useful, but been examined, or, what amounts to the he added that the brake measurements same thing, with a comparison of the obtained were inaccurate, consequently losses of power which they occasion. the table is of little value. He con- Unfortunately such a comparison has cluded his paper with a retrospective never been made experimentally, beglance at the four methods of transmis- cause hitherto the opportunity of doing sion of power which had been examined. it in a demonstrative manner has been It would appear that transmission by wanting; for the transmission of power ropes forms a class by itself, whilst the to a distance belongs rather to the three other methods combine into a natural future than to the present time. The group, because they possess a character author believes that transmission by in common of the greatest importance. ropes furnishes the highest proportion of It may be said that all three involve a useful work; but that as regards a wide temporary transformation of the me-, distribution of the transmitted power the chanical power to be utilized into poten- other two methods, by air and water, tial energy.
Also in each of these might merit a preference. methods the efficiency of transmission is The discussion which followed, the the product of three factors or partial author being absent, was opened by Mr. efficiencies which correspond exactly - J. N. Shoolbred, who gave facts and set namely, (1) the efficiency of the insiru- forth certain experiments on the effiment which converts the actual energy ciency of electric generators, quoted in of the prime mover into potential the paper, in a form more in accordance energy; (2) the efficiency of the instru- with English ideas. He observed that ment which reconverts this potential they confirmed the previous experiments energy into actual energy, that is into of Dr. Hopkinson and others as to the motion, and delivers it up in this shape very high efficiency of such generators, for the actual operations which accom- but this of course proved nothing as to plish industrial work; (3) the efficiency of the efficiency of transmission by electhe intermediate agency which serves tricity, where the electricity, after being for the conveyance of potential energy generated, had to be reconverted into
power at the other end. In this recon- used in the transmission wore so rapidly, version Dr. Siemens' experiments showed lasting, e.g., at Schaffhausen, only twelve a loss of about 50 per cent. Recent ex- months; and suggested that they must periments of his own, however, led to either be drawn too tight, or given too the hope that this loss might be largely high a working strain. He also spoke of reduced by adopting proper precautions the great friction of water in pipes under between the two machines, the generator heavy pressure, examples of which were and the motor. Anyhow, there were given in the paper; and suggested that many ases where efficiency was of the further experiments were desirable on first importance, e. 9., where natural this subject. Mr. W. E. Rich took up a sources were utilized, or a large central point neglected in the paper, viz., the steam engine could be drawn upon, &c., proper pressure to be used in transmisand here the greater compactness and sion by compressed air. This, he held, economy of the electric transmission should be as low as was convenient, say, would give it important advantages. 30 lbs. per square inch, for dry air comMr. Alexander Siemens followed in the pressors. Air compression he considered same strain, and thought far too much was better suited to intermittent than was made of the question of efficiency, constant transmission. In the latter case which was often of little importance. the freezing at the exhaust ports was a He instanced Sir William Armstrong's great inconvenience, but this might be arrangement at Rothbury, and that remedied by placing a small fire near of Dr. Siemens at Tunbridge; and them, or otherwise.
With regard to looked forward to the time when large water engines, the greatest inconvensteam engines would be established at ience was the slide valve, which always central positions in towns, whence the gave trouble, and should be done away power would be distributed by elec- with if possible, a result already attained tricity as required. He held that a few in Mr. H. Davey's water engines, de. experiments were necessary to settle the scribed by him to the Institution in 1880. arrangements of such transmissions, be cause the conditions might always be preserved constant, by arranging the proper resistance in the leading wire; and considered that prejudice was now
REPORTS OF ENGINEERING SOCIETIES. the only thing that hampered the trans
HE AMERICAN SOCIETY OF CIVIL Engi mission of power by electric means.
NEERS. — The Society have of late engaged Mr. Fernie recalled the attention of in the discussion of the question of wind pressthe meeting from electricity, and gave ure on Bridges. Paper No. 213, by C. Shaler some examples of the extensive use of Smith, gave some interesting and valuable obtransmitted water power in Switzerland.
servations bearing on this question.
The following is an abstract from it: He mentioned that in Geneva the men For a number of years past, whenever pracwho cut firewood for house use used ticable, I have personally visited the tracks of small machines, which they worked by destructive storms as soon as possible after attaching them to high-pressure mains
their occurrence, for the purpose of determin
ing the maximun force and width of the path laid along the streets. M. Schönheyder
M. Schönheyder in each case. then drew attention to a statement in The most violent on my records are as folthe paper with regard to the wide belts lows: used in America-viz., that at high! First. - East St. Louis, 1871: Locomotive
overturned; maximum force required, 93 lbs. speeds a partial vacuum is formed be
per square foot. tween the belt and the pulley, which Second.–St. Charles, 1877: Jail destroyed; gives an adhesion more like that of an force required, 84.3 lbs. per square foot. ordinary leather sucker, and greatly in
Third.-Marshfield, Mo., 1880: Brick man
sion house leveled; force required, 58 lbs. per creases the tension which the belt will bear without slipping. M. Schönheyder Fourth.-Havre de Grace, Md., 1866: Ten altogether disbelieved in the existence of spans wooden Howe truss bridge, 250 feet each, this action-and probably with justice— blown over; force required, 27 lbs. per square though it has undoubtedly been claimed foot. in the case of American belts. He dis- of Combination Triangular truss blown over;
Fifth.-Decatur, Alabama, 1870: Two spans cussed the reason why the iron ropes force required, 26 lbs. per square foot.
Sixth.-Meredosia, Di., 1880: One span per square foot, acting in the same direction wooden Howe truss, 150 feet long, overturned; over its entire length. force, 24 lbs. per foot.
Next. - A fully loaded passenger train, and Seventh.-Omaha, Nebraska, 1877: Two
the heaviest possible freight train will leave spans iron Post truss, 250 feet each, blown the track at the respective pressures of 317 down; force required, 1876 lbs. per square and 5642 lbs. per square foot. If the braces foot.
are proportioned at 15,000 lbs. per square inch, Also, suudry cases of train derailment caused with a wind pressure of 30 Ibs. per square by wind, the maximum force required being foot, they will still be within their limit of 3014 lbs. per squre foot.
elasticity at the moment when the train is In each of the foregoing cases I have given blown from the track in either case. Destrucwhat appeared to be the maximum effort of the tion of the span will then take place, if at all, wind and the lowest pressure required to pro
from the effects of derailment; to resist which duce the observed result. It is therefore not greater strength in the wind bracing will be of unlikely that the real force of the wind in each no value. example was greater than I have given it. Next. If there is no tension in the pier colSome of the tornadoes were very destructive-- umns until 30 lbs. wind pressure is reached, the Marshfield one, for instance, having cut a and these columns are properly spliced and swath 46 miles long and 1800 feet wide, and anchored, as per specifications, there will be killed and wounded over 250 people. To the an ample margin of tensile strength in any case above cited instances may be added the Tay where this pressure may be exceeded. Bridge disaster, in whichi case 20740 lbs. per
Last.-In view of the comparative rarity square foot on train and bridge were required of these extreme strains and the consequent to destroy the piers, through the rupture of the slight fatigue to which the iron is exposed, the vertical bracing in the four bottom riers of the high stresses imposed on the wind bracing are pier, over which the train was passing when perfectly legitimate. failure began. My reasons for considering 30 fos. per square foot sufficient for a working Boethe regular February meeting, a paper specification, when the above record shows much higher pressures, are these
on “ The Fall River Bridge,” prepared by the
late E. N. Winslow, was read by the Secretary. First.-I very much doubt if a direct wind
The committee to whom was referred the or gale ever exceeds 30 lbs. per foot; whirl- ! subject of issuing a work on the “ Law and winds do exceed it, but the width of the path. Practice for Land Surveyors in the New Engway of maximum effort in these is usually very land States," reported adversely. narrow, although the general direction is
At the February meeting a paper on “Railerratic that the appearance of the debris is gen- road Signals” was read by George W. Bloderally such as to produce the impression that
gett. the vortex was much larger than was really The committee on the Metric System rethe case. With the exception of the Marsh- ported on the information obtained relative 10 field tornado, I have yet to find a storm swath the progress toward introduction of the syswhere the width of pathway, wherein the force tem into this country and the world at large. exceeded 30 lbs. per square foot, was more that 60 feet wide.
OLYTECHINIC CLUB OF THE AMERICAN INThe St. Charles tornado is a case in point.
of , This whirlwind cut a swath about 1000 feet February 24, was upon the subject of scientitic wide for 14 miles, and destroyed over 300 books, by Mr. Wm. H. Farrington, of the houses, exerting a force of over 84 lbs. per house of 'D. Van Nostrand. It was an elaborsquare foot at its point of maximum effort. ate discussion of the subject, and was full of It crossed the middle span of the St. Charles the most interesting information. bridge nearly at right angles, and developed a The noticeable feature of modern scientific pressure of 524 lbs. per square foot in pick- literature is the tendency to give science an ing up and crushing a barrel of tar, which every-day dress, and to describe many of the stood on the bridge in the path of the vortex. most ordinary vocations from a scientific The width of the vortex was distinctly marked standpoint. on the span by the circle in which the tar was At the present time at least ten divisions are spun around, the wreckage left upon it, and needed in order to reasonably classify scientific the points at which it ceased to destroy the books. The last of them, the so-called “Popflooring. This width was thus shown to be ular Science,” attempts to draw into itself all slightly over 60 feet, and, guided by this, I the forms and phases of modern scientific literwas subsequently enabled to locate the path ature. traveled by the central vortex throughout the In all languages, especially English, French entire length of the storm swath. The bridge and German, works bearing upon construction itself was uninjured, although it was only pro- take prominent places, and in this term “conportioned to withstand 30 lbs. per square foot, struction” it is intended to embrace steam en. with a strain of 20,000 lbs. per square inch on gineering, railway science, building, &c. The the braces. This span was 320 feet long, 30 engineering books easily take the foremost feet in depth, and the top chord was 120 feet rank among the works of science. above the water. I consider it very unlikely One of the earliest leading publishers of that a bridge of over 200 feet span will ever be scientific books, and one who in his day made exposed to a wind force of more than 30 lbs. this class of literature a representative one,
was John Weale, of London. We all know, I There are constant calls for books upon subpresume, what the “Weale's Series " are--the jects which are treated of in the larger and little green or red covered books, in limp or more expensive technical cyclopedias. That flexible cloth, with flush cut edges. Mr. these demands are not supplied, is largely due Weale has been dead many years, but his se to the fact that in many cases the works would ries of reasonably-priced scientific, treatises of necessity be filled with trade secrets. upon all manner of subjects still lives. It is Some of the potable scientific books were true the advancements science has made has described and their curious histories given. rendered necessary many changes in these lit- Among others the growth of Weisbach's “Metle books; some have been rewritten and en chanics” was traced, and its curious continual larged and altered as they have passed down publication in parts in Germany mentioned. through different publishers' hands; their În conclusion, Mr. Farrington said: number has been added to, until there are now “Regarding the publishing houses of scienabout 200 of them, and they have had a sale of tific books, I would state that in England two many thousands and continue to sell. To a only confine themselves exclusively to this line considerable extent engineering science is pre- - E. & F. N. Spon, and Crosby Lockwood & dominant in this series, but they cover a wide Co. Many other houses, as in this country, range of other subjects. No attempt has been publish various works in science of all kinds, made to emulate this series of Weale, unless and are heavy publishers as well, such as Longwe might mention in connection with it the mans & Co., London, or Appleton & Co., here; “Roret Manuals” and the more recent “ Actu- but Spon and Lockwood confine themselves alities Scientifiques," and the Science Series,' now to science only, and the former house of Van Nostrand, New York, begun a few deals mostly in engineering and the allied sciyears ago.
ences. Lockwoods are now the publishers of The first named of these is—or, rather, was Weale's series and many other important and -a very popular series in the French language, elaborate works. In Paris, Mallet-Bachelier, Laof compact little volumes upon technology, or croix and Dunod are the leading houses, the for. the science of the workshop, and were largely mer, successor to Gautier-Villars, deal mostly embraced within the domain of applied chem- in mathematical books, and the latter mainly istry. The ' Actualities Scientifiques of in engineering. architectural and hydraulic Mallet-Bachelier, Paris, are no more popular works. Recently they have issued an exhaustthan the “Weale's Series,” but cover a rather ive series on engineering in all branches. wider range of subjects, and are strictly less Dubauve's “ Manuel de l'Ingénieur” in 20 ocscientific, while for Van Nostrand's we can tavo volumes and 12 quarto atlases of plates. only say, that so far as the higher branches of Dumain of Paris confines himself to military science are concerned, they would take prece- literature exclusively. In this country the dence of all, but as individual treatises are leading publishers in science alone are H. C. much less exhaustive of the subject, and in Baird & Co., of Philadelphia, and Van Nosmany instances partake more of the character trand and John Wiley & Sons, of this city. of a monograph on some special branch. The former house publishes books of an excluSome of Mr. Weale's other publications, such sively practical nature, or, as they term it, as his collections of plans and drawings of Industrial Science." Van Nostrand, on the bridges, with descriptive text, his large and ex- other hand, has more of the theoretical class haustive works upon the “ Steam Engine ” and on his list, and al combines with these milion “ Railways," his fine volumes on Archi- tary and naval science. The Messrs. Wiley tecture,” his “Quarterly Papers on Engineer have never confined themselves solely to science, ing,” and another series in the same style on They are possibly doing so more of late, but “ Architecture,” while expensive as books, are still they deal in some miscellaneous literature, remarkable examples of scientific literature, as well as in biblical. and remain as monuments to the man John Large numbers of publishers, however, Weale more enduring than brass or stone throughout the country are turning their atten
The relatively high price of scientific works tion to works in science, and the number of was spoken of at length, and the reasons for it books issued are increasing year by year. The pointed out. These were the comparatively proportion of scientific works published in small editions which can be sold, and the this country, however, to the whole number in greater expense entailed in the original prepar- other branches of literature, is relatively small, ation of the work. Tabulated work, algebraic arii, in comparison to what the Germans and formula, with cuts and diagrams, largely in- French are giving to the world, would seem crease the expenses of production. In Eng- quite insignificant. In closing these remarks, land, publishers of scientific books do pot, as I would like to say that now that the apprena rule, electrotype their works, preferring, tice system has been virtually abandoned, when an edition is exhausted, to prepare a re- young men, who are learning a trade, have to vised edition. In this country electrotyping depend largely upon their own studiousness to is the rule, hence different editions are brought become proficient in their line of work. To out with only trifling variations.
this end these books, of which I have been It is a noticeable fact that Rankine's works, speaking, are the essential helps, and I really though of the highest character-one might think that, with the array of volumes préalmost say abstruse—have had a large and sented, little excuse exists for any consciensteady sale in this country. This is a fact that. liou workman to remai in ignorance the to say the least, speaks well for the ability of requirements of the trade of his choice, or our students.
fail to attain a fair proficiency in it. VOL. XXIV.No. 4-24.
it on to one of the lines of rails leading to the
face of the excavation. He has already put in ON From abstracts "f Inst. of Civil Engi: heitither line ok i palls; and the same coupling neers) — This tramway is in use at Strasburg which bas conveyed the empty skip picks up for removing the earth from a ditch, 22 feet the full skip in passing, attaches it to deep, forming part of the new system of forti. the rope and takes it away along the fications. Siarting from the lowest point of tramway. Thus the whole number of the excavation, it is carried first through a 'men employed on the tramway, as apart short tunnel at a rise of 1 in 10, then passes from the excavation, is only six at the most. over a railway (which is protected by a tem. The engine employed is of 8 HP., but 2 to 3 porary roofing) and thence is led borizontally HP. is found to be all that is required for the to its farther or discharging end, the total work. The laying down of the tramway was length being about 1,000 yards. A peculiari- completed, though in the depth of winter, in ty of the system is that the roads, as they may less than ten weeks; and Herr Bleichert, the be termed, on which the skips of earth travel inventor, states that he has tramways at work are not of wire rope, as usual, but of round on this system which are 2,400 yards long, bar iron. Of these there are two lengths, 5 with gradients of 1 in 34, and conveying earth feet 9 inches apart--one having a diameter of to the extent of 500 cubic yard per day.17 inch for the loaded skips, and the other hav- | Deutsche Bauzeitung. ing a diameter of 1.02 inch for the empty ones. They are welded up into lengths of about 55 yards, and these lengths are afterwards united the neighborhood of Aarlberg, under the by steel couplings, having a diameter as little direction of the Spanish General Ibanez, for differing from their own as possible. These measuring the base of the network of Swiss “roads” are anchored down to the ground at triangulation, have been very satisfactory. the loading end, but at the other end terminate The base has been measured twice. The rein chains which pass over pulleys and support sult of the first measurement was 2400.087 mehanging weights, sufficient to bring a strain of ters (1.502 miles); the second operation, which 44 tons on the stronger “road," and 372 tons was conducted entirely independently of the on the weaker. There are forty intermediate first, for the purpose of verification, gave supports of timber (some of them above 100 2400.085 meters. The difference between the yards apart), carrying at the top small grooved two measurements was only two millimeters, pulleys or which the rope actually rests. The or less than one ten-thousandth of one per cent: skips are made entirely of wrought iron, much The place chosen for the base is on the route like a dredger bucket. They weigh about 290 of Sisselen, where a perfectly straight and lbs , and carry 812 cubic feet, the total weight nearly horizontal line may be drawn for a distransported being thus about 1,000 lbs. They tance of about three kilometers (1.864 miles). are hung on gudgeons, and empty themselves Similar measurements are to be made in the by turuing over as soon as a single fastening is valleys of Tessin and of the Rhine. loosened. There are special mechanical armonnements for mennecting the hanging bkip
. T'E.SEZ: CANOAS TONNAGEhifpå total of which travel on the fixed “road." The whole passed through the Suez Canal in 1880, the is connected with a running endless wire rope share of England was 3,446,431 1ons, or more which communicates the motion. It is g inch than three-fourths of the whole. The increase, in diameter, is driven by a portable engine at compared with 1879, was from 2,508 524 Eng. the loading end, and is kept taut by passing lish, and a total of 3,236,942 tons. Next to round a counterweighted sheave of 5 feet ġ England the most marked augmentation was inches diameter, capable of traveling upon that of the Russian flag, which rose from 8799 cast iron guides. The speed of the running tons to 45,899 tons. French tonnage remained rope is in general about 4 feet per second almost stationary, having only advanced from Small steel couplings are fixed on it at iuter. 262,017 tons to 271,598. German rose from 21,vals of 130 feet, and to these the successive 548 to 52,551; Austrian, from 51,400 to 103,skips are attached--the mechanism both for 030; Spanish, from 64,468 to 84,519; Italian, attaching and disengaging being self-acting. from 94,162 to 104,567; and Dutch from 159,At the discharging end there is an apparatus 024 to 174,485. All the principal countries of of iron rails for transferring the skips from Europe shared in the improved trade with the one road to the other; by making this portable East in 1880. and providing it with supports it is further utilized for shifting the ends of the tramway and the point of loading so as to follow the
IRON AND STEEL NOTES. progress of the excavation. With the speed of rope and distance between skips given above
A the quantity of earth conveyed is about 40 ing the past week Messrs. Jessop & cubic yards per hour. The changing of the Sons, Brightside Steelworks, Sheffield, cast skips at the loading point (and similarly at the the largest crucible steel casting that has yet discharging point) is managed by a single been produced. It is a spur ring 28 feet in workman. Each empty skip, as it comes upon diameter, machine moulded, and cast whole. the return road, detaches itself just before it to cast it 270 pots were used, each pot holding reaches the workman, who receives and pushes 80 pounds weight of molten steel. When the