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 less 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 beactly resembling in minature 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. It may be said that all three involve a temporary transformation of the mechanical power to be utilized into potential energy. Also in each of these 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 instru- 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

ropes furnishes the highest proportion of useful work; but that as regards a wide distribution of the transmitted power the other two methods, by air and water, might merit a preference.

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 g., 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 steam engines would be established at central positions in towns, whence the power would be distributed by electricity as required. He held that a few experiments were necessary to settle the arrangements of such transmissions, be cause the conditions might always be preserved constant, by arranging the proper resistance in the leading wire; REPORTS OF ENGINEERING SOCIETIES. and considered that prejudice was now the only thing that hampered the transmission of power by electric means.

Mr. Fernie recalled the attention of the meeting from electricity, and gave some examples of the extensive use of transmitted water power in Switzerland. He mentioned that in Geneva the men who cut firewood for house use used small machines, which they worked by attaching them to high-pressure mains laid along the streets. M. Schönheyder then drew attention to a statement in the paper with regard to the wide belts used in America-viz., that at high speeds a partial vacuum is formed between the belt and the pulley, which gives an adhesion more like that of an ordinary leather sucker, and greatly increases the tension which the belt will bear without slipping. M. Schönheyder altogether disbelieved in the existence of this action-and probably with justicethough it has undoubtedly been claimed in the case of American belts. He discussed the reason why the iron ropes

water engines, the greatest inconvenience was the slide valve, which always gave trouble, and should be done away with if possible, a result already attained in Mr. H. Davey's water engines, described by him to the Institution in 1880.

HE AMERICAN SOCIETY OF CIVIL ENGI

NEERS. The Society have of late engaged in the discussion of the question of wind pressure on Bridges. Paper No 213, by C. Shaler Smith, gave some interesting and valuable observations bearing on this question.

The following is an abstract from it:

For a number of years past, whenever practicable, I have personally visited the tracks of destructive storms as soon as possible after their occurrence, for the purpose of determining the maximun force and width of the path in each case.

The most violent on my records are as fol

lows:

overturned; maximum force required, 93 lbs. per square foot.

First.-East St. Louis, 1871: Locomotive

Second.-St. Charles, 1877: Jail destroyed; force required, 84.3 lbs. per square foot.

Third.-Marshfield, Mo., 1880: Brick mansion house leveled; force required, 58 lbs. per square foot.

Fourth.-Havre de Grace, Md., 1866: Ten spans wooden Howe truss bridge, 250 feet each, blown over; force required, 27 lbs. per square foot.

of Combination Triangular truss blown over; Fifth.-Decatur, Alabama, 1870: Two spans force required, 26 lbs. per square foot.

Sixth.-Meredosia, Ill., 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.

Seventh.-Omaha, Nebraska, 1877: spans iron Post truss, 250 feet each, down; force required, 18% lbs. per square foot.

Next.-A fully loaded passenger train, and Two the heaviest possible freight train will leave blown the track at the respective pressures of 31 and 561⁄2 lbs. per square foot. If the braces are proportioned at 15,000 lbs. per square inch, with a wind pressure of 30 lbs. per square foot, they will still be within their limit of elasticity at the moment when the train is blown from the track in either case. Destruction of the span will then take place, if at all, from the effects of derailment; to resist which greater strength in the wind bracing will be of no value.

Also, sundry cases of train derailment caused by wind, the maximum force required being 30 lbs. per squre foot.

In each of the foregoing cases I have given what appeared to be the maximum effort of the wind and the lowest pressure required to produce the observed result. It is therefore not unlikely that the real force of the wind in each example was greater than I have given it. Some of the tornadoes were very destructive-the Marshfield one, for instance, having cut a swath 46 miles long and 1800 feet wide, and killed and wounded over 250 people. To the above cited instances may be added the Tay Bridge disaster, in which case 20 lbs. per square foot on train and bridge were required to destroy the piers, through the rupture of the vertical bracing in the four bottom tiers of the pier, over which the train was passing when failure began. My reasons for considering 30

Next. If there is no tension in the pier columns until 30 lbs. wind pressure is reached, and these columns are properly spliced and anchored, as per specifications, there will be an ample margin of tensile strength in any case where this pressure may be exceeded.

Last.-In view of the comparative rarity of these extreme strains and the consequent slight fatigue to which the iron is exposed, the high stresses imposed on the wind bracing are perfectly legitimate.

lbs. per square foot sufficient for a working B

specification, when the above record shows much higher pressures, are these

OSTON SOCIETY OF CIVIL ENGINEERS.-At the regular February meeting, a paper on "The Fall River Bridge," prepared by the late E. N. Winslow, was read by the Secretary.

The committee to whom was referred the subject of issuing a work on the "Law and Practice for Land Surveyors in the New England States," reported adversely.

First.-I very much doubt if a direct wind or gale ever exceeds 30 lbs. per foot; whirlwinds do exceed it, but the width of the pathway of maximum effort in these is usually very narrow, although the general direction is SO 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 case. With the exception of the Marshfield tornado, I have yet to find a storm swath where the width of pathway, wherein the force exceeded 30 lbs. per square foot, was more that 60 feet wide.

The committee on the Metric System reported on the information obtained relative to the progress toward introduction of the system into this country and the world at large.

St. Charles tornado is a case in point. POTUIN. The paper of the CANLY.

DOLYTECHINIC CLUB OF THE AMERICAN IN

This whirlwind cut a swath about 1000 feet wide for 14 miles, and destroyed over 300 houses, exerting a force of over 84 lbs. per square foot at its point of maximum effort. It crossed the middle span of the St. Charles bridge nearly at right angles, and developed a pressure of 52 lbs. per square foot in picking up and crushing a barrel of tar, which stood on the bridge in the path of the vortex. The width of the vortex was distinctly marked on the span by the circle in which the tar was spun around, the wreckage left upon it, and the points at which it ceased to destroy the flooring. This width was thus shown to be slightly over 60 feet, and, guided by this, I was subsequently enabled to locate the path traveled by the central vortex throughout the entire length of the storm swath. The bridge itself was uninjured, although it was only proportioned to withstand 30 lbs. per square foot, with a strain of 20,000 lbs. per square inch on the braces. This span was 320 feet long, 30 feet in depth, and the top chord was 120 feet above the water. I consider it very unlikely that a bridge of over 200 feet span will ever be exposed to a wind force of more than 30 lbs.

February 24, was upon the subject of scientific books, by Mr. Win. H. Farrington, of the house of D. Van Nostrand. It was an elaborate discussion of the subject, and was full of the most interesting information.

The noticeable feature of modern scientific literature is the tendency to give science an every-day dress, and to describe many of the most ordinary vocations from a scientific standpoint.

At the present time at least ten divisions are needed in order to reasonably classify scientific books. The last of them, the so-called "Popular Science," attempts to draw into itself all the forms and phases of modern scientific literature.

In all languages, especially English, French and German, works bearing upon construction take prominent places, and in this term "construction" it is intended to embrace steam en gineering, railway science, building, &c. The engineering books easily take the foremost rank among the works of science.

One of the earliest leading publishers of scientific books, and one who in his day made 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 notable 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 In 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 Weale's series and many other important and elaborate works. In Paris, Mallet-Bachelier, Lacroix and Dunod are the leading houses, the former, successor to Gautier-Villars, deal mostly in mathematical books, and the latter mainly in engineering, architectural and hydraulic works. Recently they have issued an exhaustive series on engineering in all branches. Dubauve's "Manuel de l'Ingénieur" in 20 octavo volumes and 12 quarto atlases of plates. Dumain of Paris confines himself to military literature exclusively. In this country the leading publishers in science alone are H. C. Baird & Co., of Philadelphia, and Van Nostrand and John Wiley & Sons, of this city. The former house publishes books of an exclusively practical nature, or, as they term it,

The first named of these is-or, rather, was -a very popular series in the French language, of compact little volumes upon technology, or the science of the workshop, and were largely embraced within the domain of applied chemistry. The Actualities Scientifiques" of Mallet-Bachelier, Paris, are no more popular than the "Weale's Series," but cover a rather wider range of subjects, and are strictly less scientific, while for Van Nostrand's we can only say, that so far as the higher branches of science are concerned, they would take precedence of all, but as individual treatises are much less exhaustive of the subject, and in many instances partake more of the character of a monograph on some special branch. Some of Mr. Weale's other publications, such as his collections of plans and drawings of bridges, with descriptive text, his large and exhaustive works upon the Steam Engine" and on "Railways," his fine volumes on Architecture," his " Quarterly Papers on Engineer ing," and another series in the same style on "Architecture," while expensive as books, are remarkable examples of scientific literature, and remain as monuments to the man John Weale more enduring than brass or stone

The relatively high price of scientific works was spoken of at length, and the reasons for it pointed out. These were the comparatively small editions which can be sold, and the greater expense entailed in the original preparation of the work. Tabulated work, algebraic formula, with cuts and diagrams, largely increase the expenses of production. In England, publishers of scientific books do not, as a rule, electrotype their works, preferring, when an edition is exhausted, to prepare a revised edition. In this country electrotyping is the rule, hence different editions are brought out with only trifling variations.

It is a noticeable fact that Rankine's works, though of the highest character-one might almost say abstruse-have had a large and steady sale in this country. This is a fact that. to say the least, speaks well for the ability of our students.

VOL. XXIV.-No. 4-24.

Industrial Science. Van Nostrand, on the other hand, has more of the theoretical class on his list, and also combines with these military and naval science. The Messrs. Wiley have never confined themselves solely to science, They are possibly doing so more of late, but still they deal in some miscellaneous literature, as well as in biblical.

Large numbers of publishers, however, throughout the country are turning their attention to works in science, and the number of books issued are increasing year by year. The proportion of scientific works published in this country, however, to the whole number in other branches of literature, is relatively small, and, in comparison to what the Germans and French are giving to the world, would seem quite insignificant. In closing these remarks, I would like to say that now that the apprentice system has been virtually abandoned, young men, who are learning a trade, have to depend largely upon their own studiousness to become proficient in their line of work. To this end these books, of which I have been speaking, are the essential helps, and I really think that, with the array of volumes presented, little excuse exists for any conscientious workman to remain in ignorance of the requirements of the trade of his choice, or fail to attain a fair proficiency in it.

"roads

ENGINEERING NOTES

Thus the whole number

of

men employed on the tramway, as apart from the excavation, is only six at the most. The engine employed is of 8 HP., but 2 to 3 HP. is found to be all that is required for the work. The laying down of the tramway was completed, though in the depth of winter, in less than ten weeks; and Herr Bleichert, the inventor, states that he has tramways at work on this system which are 2,400 yards long, with gradients of 1 in 34, and conveying earth to the extent of 500 cubic yard per day.Deutsche Bauzeitung.

S

WISS TRIANGULATION.-The operations in the neighborhood of Aarlberg, under the direction of the Spanish General Ibanez, for measuring the base of the network of Swiss triangulation, have been very satisfactory. The base has been measured twice. The result of the first measurement was 2400.087 meters (1.502 miles); the second operation, which was conducted entirely independently of the first, for the purpose of verification, gave 2400.085 meters. The difference between the two measurements was only two millimeters, or less than one ten-thousandth of one per cent The place chosen for the base is on the route of Sisselen, where a perfectly straight and nearly horizontal line may be drawn for a distance of about three kilometers (1.864 miles). Similar measurements are to be made in the valleys of Tessin and of the Rhine.

it on to one of the lines of rails leading to the face of the excavation. He has already put in NA ROPE TRAMWAY AT STRASBURG.--position a full skip which has just arrived by (From abstracts of Inst. of Civil Engi- the other line of rails; and the same coupling neers) This tramway is in use at Strasburg which has 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. Starting from the lowest point of tramway. the excavation, it is carried first through a short tunnel at a rise of 1 in 10, then passes over a railway (which is protected by a temporary roofing) and thence is led horizontally to its farther or discharging end, the total length being about 1,000 yards. A peculiarity of the system is that the roads, as they may be termed, on which the skips of earth travel are not of wire rope, as usual, but of round bar iron. Of these there are two lengths, 5 feet 9 inches apart-one having a diameter of 14inch for the loaded skips, and the other having 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 by steel couplings, having a diameter as little differing from their own as possible. These are anchored down to the ground at the loading end, but at the other end terminate in chains which pass over pulleys and support hanging weights, sufficient to bring a strain of 41⁄2 tons on the stronger "road," and 31⁄2 tons on the weaker. There are forty intermediate supports of timber (some of them above 100 yards apart), carrying at the top small grooved pulleys on which the rope actually rests. The skips are made entirely of wrought iron, much like a dredger bucket. They weigh about 290 lbs, and carry 81% cubic feet, the total weight transported being thus about 1,000 lbs. They are hung on gudgeons, and empty themselves by turning over as soon as a single fastening is loosened. There are special mechanical arrangements for connecting the hanging skip with a small frame above, carrying two wheels which travel on the fixed "road." The whole is connected with a running endless wire rope which communicates the motion. It is inch in diameter, is driven by a portable engine at the loading end, and is kept taut by passing round a counterweighted sheave of 5 feet 9 inches diameter, capable of traveling upon cast iron guides. The speed of the running rope is in general about 4 feet per second. Small steel couplings are fixed on it at intervals of 130 feet, and to these the successive skips are attached-the mechanism both for attaching and disengaging being self-acting. At the discharging end there is an apparatus of iron rails for transferring the skips from one road to the other; by making this portable 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 progress of the excavation. With the speed of rope and distance between skips given above the quantity of earth conveyed is about 40 A GREAT CRUCIBLE STEEL CASTING.-Dur

cubic yards per hour. The changing of the skips at the loading point (and similarly at the discharging point) is managed by a single workman. Each empty skip, as it comes upon the return road, detaches itself just before it reaches the workman, who receives and pushes

THE SUEZ CANAL TONNAGE of a total of 3,446,431 tons gross of shipping that passed through the Suez Canal in 1880, the share of England was 3,446,431 tons, or more than three-fourths of the whole. The increase, compared with 1879, was from 2,508 524 English, and a total of 3,236,942 tons. Next to England the most marked augmentation was that of the Russian flag, which rose from 8799 tons to 45,899 tons. French tonnage remained almost stationary, having only advanced from 262,017 tons to 271,598. German rose from 21,548 to 52,551; Austrian, from 51,400 to 103,030; Spanish, from 64,468 to 84,519; Italian, from 94,162 to 104,567; and Dutch from 159,024 to 174,485. All the principal countries of Europe shared in the improved trade with the East in 1880.

IRON AND STEEL NOTES.

ing the past week Messrs. Jessop & Sons, Brightside Steelworks, Sheffield, cast the largest crucible steel casting that has yet been produced. It is a spur ring 28 feet in diameter, machine moulded, and cast whole. To cast it 270 pots were used, each pot holding 80 pounds weight of molten steel. When the