HYDRAULICS OF FIRE STREAl\I. . THE combustible nature of many of the buildings

in America, owing to the free use of t~mber in th.eir construction, has led to very great Interest being taken there in fire-resisting appliances, not only among property ~wners, but al.so by . t he. general public. The efficie.n~y of the .bngades ~s stimulated by periodic compet1t10ns, while t he officers of t he insurance corporations exhibit the gr eatest interest in all improvements tending to r ender buildings bet ter fl.ble to resist combustion, and in new appliances for the purpose of extinguishing fires. Among the many cle.vices ~hich have been i.ntro-duced from time to time to Increase the efficiency

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of the briaades, there have been many form of nozzles d;signed to produce jets of exceptional solidity and power. Some little time ago a large number of these nozzles were submitted to exact tests by Mr. J ohn R. Freeman at the expense. of the Associated Factory Mutual Insurance Companies of New England and P ennsylvania. These experi-ments were carried out with the very greatest care, and have a value for many purposes besides those of fire brigades.

Each nozzle was t ested in conjunction with a short ''play pipe " of very much larger diameter than itself, and the coefficient of discharge obtained was practically that of play pipe and nozzle com-bined. The pressure of water at the base of the play pipe was most carefully measured by means of a. peizometer. This consisted of a. ring (Figs. 1 and 2) surrour.ding the pipe and connected t o it by four holes drilled exactly square to the pipe and without burrs. From the ring there was led a pipe to a fixed mercurial column, on which the pressure could be read within 0.15 of a pound. The discharge from the nozzle was measured in a tank which had been very carefully calibrated. The jet was first allowed to become steady, run-ning to waste, and was then deflected against a screen, which guided the water into a tank for a certain interval of time, which was read by a stop-watch to the tenth of a second. The a1nount of water caught was then read off, and the discharge calculated in gallons per minute. The dian1eters of the nozzles were taken with fine micrometer cal-lipers, and were believed t o be correct within

rr~" in. In speaking of the many precautions taken, many of which we have not space t o notice, Mr. Freeman says: "To sum the whole matter up, we may have confidence that in general our determina.tions of the coefficient of discharge of nozzles were certainly correct within one-half of

E N G I N E E R I N G. 1 per cent. , and that probably the mean of. tl~e values found for a. given nozzle was correct within a somewhat smaller limit ."

Figs. 3 to 9 show examples of the forms of nozzles most generally used, while the Table on page 718 gives the results of the t~sts.

I t will be seen that the coefficients decrease as the diameter increases from . 083 for a to . !J71 for e. The larger coefticient of the !-in. a~d J in. nozzles is due to the relative decrease of fnctwn loss con-sequent on the area of t he waterway through the play pipe bearing a larger r~tio t o the ~r:ea of the nozzle and the smaller coefficient of the 1~-1n. nozzle is due' to the r elatively small size of throat, or small end of the play pipe. Several other cones of the

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same general character as those engraved were tested, the coefficient varying 1nostly from . 971 to .978. Two nozzles, however, fell below this standard ; they are illustrated in Figs. 10 and 11. The latter had a coefficient of . 946 owing to in-creased friction due t o the narrowness of the water-way near the down stream end of the play pipe. In Fig. 10 the coefficient was . 961, the r eduction being produced by inserting a hollow cone, which formed a sharp-cornered ridge projecting into the waterway -frr in. When the cone was removed the coefficient was . 976.

These experiments show that the coefficient of discharge of nozzles is not very sensitive to pecu-liarities of form and finish, but that nozzles of the same general style made at different times and places may be relied upon to give, for a given pressure and area of outlet, discharges which are identical within t he practical limits of measure-ment. Mr. Freen1an argues fron1 this that by means of smooth hose nozzles of ordinary good construction, water under high pressure may be measured with extreme accuracy, and that this method of tneasurement, provided an accurate

pressure gauge is at hand, ~nd is conne?ted dire~tly to the base of the play pipe by a su1ta.ble petzo-meter, is equal to all t~e requir~ments of a pump-ing engine test, and u; equal In accuracy to the ordinary weir measurement. nder: 80 lb. pres-sure four 1! -in. nozzles, connec~ed duectly to the main without hose, would discharge the full capacity of a pump lifting 2,500,000 gallons per twenty-four hours. . .

F or the information gained In }us tests, . Mr. Freen1an has designed the standard nozzle Illus-trated in Fig. 12. I t will be noticed that the end is made very heavy to resist burning, and that.the lip is cut out to prevent the edg~s of the. ~nfi~e being burred. The washer by which the JOlllt Is

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made with the play pipe is outside the latter, and cannot project into the stream, while a rim prevents it being blown out .

Some firemen have had a great belief in the efficiency of ring nozzles, but t his will be swept away by the experiments. We illustrate three forms, out of many, in Figs. 13, 14, and 15. The first has a coefficient of . 736, the second of . 713, and the third of .582. The last is not a. style in practical use, but was constructed for the sake of the experiments. The ring nozzle has sometimes an apparent advantage over the plain nozzle, since it throws a smaller jet, even when of the same dia-meter, and thus the pressure in the play pipe is better maintained when the water is delivered through a long length of hose.

vVhile making tests of the jets Mr. Freeman also investigated the loss of head due to friction in dif-ferent kinds of hose. His results are extremely interesting, and demonstrated to what an enormous exten t internal stnoothness increases the conduct~ ing power. Fourteen different specimens of 2!-in. hose were tried in all with J l -in., 1! -in. , and 1~ in. sn1ooth nozzles, and in some cases with smaller nozzles. The hydrant pressure \aried fron1 15 lb. to 125 lb. per square inch, and the delivery of the hose fron1 about 50 to 325 r nited States gallons* a minute; the corresponding mean linear velocity in some of the kinds of hoses varied fron1 3ft. to 21ft. a second. The loss of pressure by friction was found to follow the common theory of being proportional to the square of the discharge closely

* A United States gallon of water weighs Slb., or .8 of an Imperial gallon.

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718 enough for all practical purposes, but the fact that there was a sl ight divergence from the law was also clearly shown. The results of a number of experiments ar~ plotted in Fig. 18, in which the full hnes show the results and the dotted lines are mathematical curves of square plotted throuah the 240-gallon point. The length of hose varied

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50 ft. to 350 ft., and the friction loss was found to be proport:o:1al to the length. The pressures were

Pig. 18. FF?ICTION LOSS IN .CIR HOSE

figuru. 11/pYt lint-grvt-mean pf?I$Sure withinhofif-J , below - number oF txp .t J~

DoUetl curvu gwe. lo53 cu propori:.Jonrui to Sq,uare oF Quantity_ .sl:orting From l:h~ 24-0 gallon point oftJ,e curve through tht. o~crvatiDn3.

E N G I N E E R I N G. F igs. 16 and 17 show t he appearance of samples K and G. This entirely upsets the manufacturer's theory that the roughness does not matter since the w~ter "lies dead" all round the periphe;y.

To Illustrate the effects of the diameter of hose upon the loss of pressure by friction, Mr. Freeman has calculated the following Table, which is based on .the. well-known law t hat the loss of pressure van es Inversely as the fifth power of the diameter.

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T .\.ULE SHOWING COEFI'ICIENTS 01' DISCHARGE OF s~roOTll CoNE NozzLES 011' VAUIOUS SIZK?.

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J 60.0 120.:3 1 50.0 117.2 1 t 40.0 104.4 1 25.0 83.4 1

80.0 205.2 2 60.0 177.0 3 50.0 162.0 1 30.0 125.0 1 { 50.0 208.5 1 40.0 186. 4 1 30.0 161.0 1 50.0 266.5 5 ~ 40.0 238.2 4 30.0 205.9 4

20.0 169.0 2 , 54.0 344.2 2

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" 15.0 180.4 4 { 30.0 310.6 6 25.0 283.0 4 20.0 252.0 2 { 20.0 338.5 1 12.0 261.0 2

read at each end of the hose every half-minute, and several independent tests were made of each sample. Taking the specimens marked in the Table, the worst (L) was unlined linen hose ; at a discharge of 240 gallons per minute it lost about 27 lb. per 100ft. of length. The rough rubber lined hose J{ was nearly as bad; under the same conditions it lost 24 lb. A notable improvement is seen when we come to the very smooth rubber-l ined hose D , and the medium rubber-lined hose G t hese both lost about 12 lb. The leather hose J iost 11lb., and the very smooth solid r ubber hose A 10 lb. Thus between the best and the worst the loss varied from 10 lb. to 27 lb. per 100 ft. This difference was entirely due to the varieties in the smoothness of surface in the hose. Mr. Freeman devised a most ingenious method of demonstrating whn.t the interior was liko; he filled up a piece of hose with plaster-of-paris, and then applied a water pressure of 100 lb. per square inch until the plaster set. The result.ing cylinder was then cut out.

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1.21 81.21 109.90 .91 60.91 95. 18 .74 50.74 86.87 .44 30.44 67.29

1.26 51.26 87.31 1.00 41. 00 78.09 .74 30.74 67.62

2.04 52.04 87.97 1.64 41.64 78.70 1.22 31.22 68.15 .82 20.82 55.65

3.40 57.40 92.40 3.18 63.18 88.93 2.50 42.50 79.51 1.86 31.86 68.84 1.56 26.56 62.84 .9-l 15.94 48.69

2.80 32.80 69.84 2.2$ I 27.28 63.70 1.82 21.82 56.96 3.31 23.31 58.87 1.95 13.95 I 45.55

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F. E. Kir by, of Detroit, Mich., consulting and constructing engineer Detroit Drydock Company; Stevenson Taylor, general manager W. and A. Fletcher Company; J. W. Miller (associate), of New York, president Providence and Stonington Steamship Company; Lewis Nixon, of Philadelphia, Pa.., general manager hull department William Cramp and Sons' Ship and Engine Building Com-pany; C. B. Orcutt, of New York, president New-port News Shipbuilding Company; J. F. Pank-hurst, of Cleveland, Ohio, vice-president and general manager Globe Iron Works; Harrington Putnam (associate), of New York, counsellor-at-law; W. T. Sampson (associate), of Washington, D. C., Commodore, U.S. Navy, Chief of Bureau of Ord-nance; H orace See, of New York, consulting engineer and na.val architect; E. A. Stevens (asso-ciate), of H oboken, N .J., president Hoboken Ferries; G. E. Weed, of New York, pres~dent M organ Iron 'Vorks ; F. W. Wheeler, of West Bay City, Mich., president F. W. Wheeler Ship-yard and Drydock Company.

Executive Committee: Francis T. Bowles, chair-man; H. T. Gause, E. A. Stevens, Lewis Nixon, Harrington Putnam, C. A. Griscom, ex officio; W. L . Capps, ex officio.

The object of the Society is "the promotion of the art of shipbuilding, commercial and naval, ': and to be a member, one must be a naval architect or marine engineer, or a professor of naval archi-tecture or mechanical engineering, and he must be not less t han twenty-five years old, and have been in a responsible position for at least three years. The meeting was extremely well attended, and many of the most prominent engineers in the United States were present; among them your correspondent noted the following : J. F. Holloway, Past-Presi-dent of the Mechanical Engineers ; Professor J. E. Denton, Stevens Institute, Hoboken, N.J. ; Professor W. F. Durand, Cornell University, Ithaca, N. Y. ; S. Dana Greene, General Electric Company, New York; Jas. T. Boyd, general manager George F. Blake Manufacturing Corn-pany, New York; C. H. Haswell, New York ; H. B. Roelker, New York ; A. A. Henderson, Chief Engineer, U. S.N.; A. P. .Niblack, Lieutenant, U.S.N.; J. J. Woodward, Naval Constructor, U.S.N.; A. H. Raynal, superintendent S. L. Moore and Sons' Company, E lizabeth, N.J.; Professor C. H. Peabody, Massachusetts Institute of Technology, Boston; F. M. Wheeler, Wheeler Condenser and Engineering Company, New York; R . W. Daven-port, vice-president of the Bethlehem Iron Com-pany, South Bethlehem, Pa. ; Charles E. Emory, New York ; G. A. Cormack, secretary of the Corinthian Yacht Club; Wm. Gardner, 1, Broad-way, New York; C. D. Mosher, 1, Broadway, New York ; Colonel H. G. Prout, editor of the B ail1oad Gazette; M. N. F orney, editor of the A me1ican Enginee? and R ctJil?oad Jmwnctl; Charles Kirchoff, editor of the b on Age; M. N. Baker, associate editor of the Enginee?ing N ews; S. D. V. Burr, mechanical editor of the I1on Age ; W. M. McFar-land, Bureau Steam Engineering, U.S.N. , Wash-ington; Colonel E. A. Stevens, president of the H oboken F erries, Hoboken, N.J.; Francis T. Bowles, Naval Constructor, U.S.N., Norfolk, Va.; and there were many others of equal distinction, but your correspondent is not blessed as was A rgus, hence can only note those within the range of one pair of eyes.

The first paper was entitled, "Evolution of the Atlantic Greyhound, " by Chas . H. Cramp, of Philadelphia. He contrasted the caravels of Columbus with the Lucania, and said this was the evolution of four hundred years. H e considered the great start in record-breaking was when the Inman Company in 1869 sent out the City of Brussels, which reduced the time of 8 days 4 hours 1 minute to 7 days 22 hours 3 minutes. This ship was 390ft. long, 40ft. 4 in. beam, and 3090 tons gross. Her displacement at 26ft. load was 6900 tons. The engines were simple direct-acting, two 90-in. cylinders with 54 in. stroke, and steam at 30 lb. Indicated horse-power, 3020; average speed, 14.53 knots. Next came the Oceanic (White Star Com-pany), 3808 t ons gross, 420 ft. long, 40. 9 ft. beam, and depth for t onnage 23.4 ft. Engines were com-pound, with four cylinders-high-pressure 29 in. in diameter, and low-pressure 78 in. ; tandem, with 60-in. stroke, and 66 lb. steam. The same com-pany brought out in 1871 the Adriatic and Celtic. These boats ~ere 3886 gross tons, 417 ft. long and 41 ft. beam, had four-cylinder compound engines, high-pressure cylinders 41 in. and low-pressure

E N G I N E E R I N G. 78 in. in diameter, and 60 in. stroke, carrying 80 lb. of steam ; indicated horse-power 3880. The record was reduced to 7 days 16 hours 26 min. The American Steamship Company constructed at the Cramps' Yard the Indiana, Illinois, Pennsy 1-vania, and Ohio.

"The four ships of the American Line were com-missioned in 1872 and 1873. They a.re 357 ft. long over all, and 243 ft. between perpendiculars, 43 ft. beam, with a tonnage depth of 24ft,. United States measurement, and their gross register is 3126 t ons. They were powered with two-cylinder compound engines, having piston diameters of 48 in. and 90 in., with 48 in. stroke ; and, carrying 75 1 b. steam pressure, t hey developed about 2000 horse-power, which gave them an average speed of 14 knots. They made eight-day trips, and for a time attracted their share of the Transatlantic traffic, but, as already intimated, they succumbed at length t o the competition of their subsidised British rivals, and ult imately passed under the control of the International Navigation Company, by whom they have been considered worth re-equipment with new triple-expansion engines after twenty years of continuous service. These ships, though not so large or so high-powered as some contemporary vessels, embodied the best ship-building practice of their date as to material and workmanship, and are still creditable specimens of American shipbuilding skill twenty years ago, as well as of first-rate efficiency in their classe~."

The Adriatic, however, held the record till1874, when the Inman Company put out the City of Berlin ; gross tonnage, 5490; length, 499 ft., and 44ft. beam; tonnage depth, 34ft. Two-cylinder compound engine, high-pressure, 72 in., and low-pressure 120 in., with 66 in. stroke, and steam at 75 lb., and indicated horse-power 5200. The record now became 7 days 15 hours 28 min. The White Star Company replied with the Germanic and Britannic. Length, 455ft. ; breadth, 45ft. ; 33ft. measured depth ; gross tonnage, 5008 ; compound four-cylinder engines; high- pressure cylinder 48 in. in diameter, and low-pressure 83 in., 60 in. stroke, 75 lb. steam, and indicated horse-power 5600. The record now became 7 days 6 hours 52 minutes, and this it was in 1879, although the Cunard Company tried to lower it with the Gallia.

In the same season, however (1879), the Guion Line- a new R ichmond in this particular field, by the way--brought out the Arizona, built at Elder's, and with her took the pennant so long borne by the White Star ships. The principal dimensions of the Arizona are 450 ft. by 45.4 ft. by 35.7 ft., and she is powered with three-cylinder compound engines having one 62-in. high and two 90-in. low pressure cylinders, 66-in. stroke, and, with steam at 90 lb., developed 6640 indicated horse-power. Her gross tonnage is 5164, and her best trip was made in 7 days 3 hours 38 minutes, involving an average all-the-way speed of 16.27 knots an hour. The Arizona carried the banner, by virtue of this performance, two seasons- 1879 and 1880. This success of the Arizona stimulated the Guion people to renewed efforts, and in 1881 they brought out the Alaska, also built at Elder's (or the F air field yard), then under the able management of the late Sir William Pearce.

The Alaska's dimensions are 500ft. by 50ft. by 38 ft. moulded, with a gross tonnage of 9500, and her power is a three-cylinder compound engine having a 68-in. high-pressure and two H>O-in. low-pressure cylinders, which, carrying boiler steam at 100 lb., developed in a mean of four days' perform-ances 11,800 indicated horse-power, and drove her across the Atlantic westward in 6 days 18 hours 47 minutes, which involved an all-the-way mean speed of 17.44 knots per hour. The Alaska now took the pennant, but she did not hold it long. The Barrow Shipbuilding Company brought out the City of Rome the same year, and that vessel was put in the service by the Inman Line, the t itle to the ship remaining with her builders.

The contest between the Alaska and the Rome was fierce. Trip after trip they sped over the ocean '' neck and neck," as horsemen say, the average difference between their records being but a few minutes. Finally, however, the Rome got down to 6 days 18 hours, which beat the Alaska's best by 37 minutes, and then the Rome hoisted the banner in her turn. The R ome was the laraest ship of her day, excepting, of course, the G~eat Eastern; at all events, the largest single-screw ship up to her date. Her dimensions are 560 ft. by 52 ft. by 37 ft., her gross tonnage 8144, and her

maximum horse-power 11,500 indicated. The.Rome underwent some vicissitudes in her early htstOX:Y Her first service in the Inman Line was not satis-factory, and she was thrown back o~ the hands of her builders. They then made constderable a~terations of boiler arrangement and ~ther ~etails ~f internal economy, and she was put 1n servic.e again by the Anchor Line, where she has remained to this time.

During the year 1881 the Cunard Company brought out the Servia, built, as the Gallia was, by Thompsons. The Servia's dimensions are 615 ft. by 53ft. by 37ft., and her gross r egister is 7392 tons. Though a fine ship, t~e Servi~ .repeated the disappointment of the Galha, by failmg to reduce the record of either the Alaska or the Rome. Her propulsion was by a three-cylinder c01~pound engine having one. 72-in. high and two. 100-m. low pressures, with 72 m. stroke, and, carrymg 90 lb. of steam, she developed 10,200 indicated horse-power in her best trip, w hi eh was 6 days 23 hours 49 minutes.

In 1883 the America came out for the National Line, the Aurania for the Cunard Company, and the Oregon for the Guion Company. The last ship lowered the record to 6 days 9 hours 22 minutes, but closed her career off Long Island in a collision. Her dimensions were 501ft. by 54ft. by 38 ft., 7375 tons gross, 25 ft. draught with a displace-ment of 12,560 tons. Engines, three-cylinder com-pound. High-pressure cylinder, 70 in.; and two low-pressure, 104 in. ; 72 in. stroke, and steam at 170 lb.; horse-power, 13,200. The Aurania being a disap-pointment, the Cunard Company in 1884-5 built the Umbria and Etruria, 501ft. by 57 ft. by 38ft.; 8120tons gross; displacement at 26ft. draught, 13,38C tons ; three-cylinder compound Fa.irfield engines. The high-pressure cylinder was 71 in., the two low pressure-cylinders 105 in., with 72 in. stroke, and with 110 lb. of steam, their maximum develop-ment of horse-power has been 14,840 in the Etruria, and 14,460 in the Umbria. They reduced the record to about six days even, though each has made at least one passage slightly inside of six days. They brought the Cunard Line to the front again for the first time in several years. From 1884 to 1889 the Umbria and Etruria maintained their supremacy. It was evident that in them the pos-sibilities of single-screw propulsion had been exhausted, and owners and builders who meditated an advance beyond them had to contemplate twin screws.

During the years 1885, 1886, and 1887 there was much activity on the part of the French and Ger-mans. The latter brought out the Aller, of the North German Lloyds, in 1885, the Saale and Trave in 1886, and the Lahn in 1887 . These were British ships, built at Fairfield. They were all single-screw vessels, but they had the distinction of introducing the triple-expansion engine in Trans-atlantic propulsion. The Aller , Trave, and Saale are substantially alike in hull and fittings, and their engines are exact duplicates, except in cer-tain minor or non-essential parts. These vessels are 439 ft. in length, and register 4994 tons in the Aller to 5380 tons in the Trave and Saale, their displacement a~ 26 ft. draught be!ng 10,400 tons. Their triple-expansion engines have high-pressure cylinders 44 in., intermediate 70 in., and low-pressure 108 in., with 72 in. stroke. Carry-ing steam at 150 lb., these engines have developed 8300 indicated horse-power, and their best f U S-tained speeds have been 17.7 knots for the Aller, 17.1 knots for the Saale, and 18. 6 knots for the Trave. As the time of these ships is reckoned from Southampton, certain deductions are neces-sary for fair comparison with ships dating from Queenstown, so it is not worth while to give their records, except to say that to equalise the records of ships starting from the two points, allowances must be made in favour of the Southampton ship as follows :

For 17 knots speed, 16 hours 20 minutes. For 17! knots speed, 16 hours. F or 18 knots speed, 15 hours 30 minutes. For 18! knots speed, 14 hours 56 minutes. For 19! knots speed, 14 hours. The Lahn is 10 ft. longer, 1 ft. wider, and 10 in.

deeper than her three consorts, and her gross tonnaae is ?681. He~ engin~s are also ~f a d~fferent t.yp~, betng fiye c~lmder tr1p~e-expan ~10n, w1th two high-pressure cyhnders 32?l 1n., one Intermediate 68 in. and two lows each 85 in., the duplicate cylinder~ being arranged tandem, one high and one low working together. These engines, with 150 lb. of

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steam, developed 9800 horse-power, and produced a. speed of 18.40 knots, making a Southampton r ecord of 6 days 22 hours 42 minutes, which, at her rate of speed, is equal to a Queenstown passage of 6 days 7 hourd 30 minutes.

The Spree and Ravel, built at Stettin, in 1890, for the North German Lloyds, present no essential features different from the L1hn, and failed to lower the record.

In 1889 90 the successes of their neigh hours stimulat ed the Hamburg Company to efforts which took shape in the Columbia, N orma.nnia, and Prince Bismarck. The Columbia was built by Lairds, and the N ormannia at Fairfield ; the Bismarck being the only one of th3 thr~e built at home. The Columbia's dimensions are 463.5 ft. by 55.6 ft. by 35.5 ft.: and her gross register is 7363 tons. Her twin screw.i are driven by t.wo threecylinder triple-expan3ion engines, with cylinder diameters of 41 in., 66 in., and 100 in., and 66 in. stroke. With steam at 150 lb. these engines have developed 14,600 collective indicated horse-power, producing mel.n speed for a. passage of 19.15 knots, and a Southampton record of 6 days 14 hours 2 minutes ; equivalent to a Queenstown record of about 6 days. TheN orma.nnia is largar than the Columbia, and has more powerful machinery.

The Normannia's dimensions are 500 ft. by 57 5 ft. by 34 ft., and she tons 8250. Her triple-expansion engines have cylinders 40 in., 67 in., and 106 in., with 66-in. stroke, and, carrying steam at 150 lb., they have developed over 15,000 indicated horse-power. Her best mean speed for a passage has been 19.33 knots. The Fiirst Bis-marck is chiefly remarkable as being the most important commercial ship ever built in Germany, and as a r esult of the policy adopted by the German Emperor to encourage home shipbuilding by m~king marked discrimina.tions in favour of such ships a~ compared with those built abroad. Her dimensions are 502.6 ft. by 57.6 ft. by 38 ft., and her tonnage 8874. ller engines are triple, with cylinder diameters of 43{ij- in., 66"1)6" in., and 106 [6 in., having a stroke of 63 in. She is re-por ted to have developed 16,800 indicated horse-power, as a mean of six days on the trip which gave her, for a brief period, the Southampton record.

D..tring all this effort on the part of the English nnd Germlns, the French remained quiescent until 1836-87, when they brought forward the Cham-patYne and Bretagne, built at St. N azaire, and the Bo

0urgogne and Gascogne, built by the Forges et

Chantiers de la. Mediterranee. These ships differ but little in dimensions or performance, and detail of them is hardly necessary. except to say that their t onnage i ~ from 7087 to 7395 gross; they have com-pound engines of about 9800 indica.ted horse-power on a single screw, and the smartest of them, the Bourgogne, has made a Havre and Sandy Hook record of 7 days and 9 hours, which, at her rate of speed, 17.91 knots, is equal to a Queenstown record of 6 days and 13 hours. These ships satisfied the French until 1891, when they brought out the Touraine, built at St. N azaire. She is the first French liner equipped with twin screws . Her dimensions are 520 ft. by 56 ft. by 34 ft., and she tons 8863 gross. Her engines are three-cylinder, triple-expansion. Cylinder dimensions 41 in., 60t in., and 100 in., with 65 in. stroke, and, carry-ing 140 lb. of steam, they have developed a mean averao-e of 13,600 indicated horse-power (French), which drove her from Havre to Sandy Hook in 7 days 3 hours and 5 minutes, equivalent to a Queenstown record of 6 days 4 hours and 35 minutes. While the Touraine has not made any whole-trip record to compare with the Paris or Teutonic, she has shown some remarkable spurts.

The author then passed to a consideration of the New York Paris, Majestic, Teutonic, Campa.nia, and Lucania. They were not described in detail, but he claimed that the International Navigation Company were entitled to the ~redit of first J;>U~t~ng twin screws into passenger shtps, and subd1v1d1ng the hull so as to make it unsinkable when three compartments were flooded. He claimed that there had been no improvement in model througho?t. He asserted : "The principal fad of the great Enghsh builders is an aversion to statical stability, a re-pugnance to me~~centric height: As one of their standard authorities remarked In a recent paper : 'A ship will roll ; you cannot help that. There fore the problem is to mak~ he~ period as l_ong 7nd her motion as easy as possible. In pursUlt of an e::..sy r vll' they persisten~ly design their models

E N G I N E E R I N G. without initial stability, and then make them stand up by great quantit ies of water ballast or other dead weight which pays nothing. \Vhen I under-took the design of the two steamships now building under our shipyard, Nos. 277 and 278, I avoided this fad at the outset."

The author believed that any design which con-templates the carriage of water ballast (or other dead weight not cargo or coal) as an inseparable condition of stability under any circumstances is radically defective and should be condemned.

" Under such a system no ad vantage can be taken of decreased draught caused by consumption of coal or absence of cargo, but the ship must always be kept down to a load draught in order to stand up.

" This is a purely English fad, and the English designers stick to it with characteristic tenacity. In this, as in many other fads, the English appear tenacious in the exact ratio of the density of their error.

" The proposition that you must carry 1000 or 2000 tons of dead weight in water ballast when you happen to be short of cargo or run down in coal, is one that I cannot really discuss with patience when it is possible to build the ship on lines that will make her stand alone without de-triment to any other desirable quality, and with vast improvement to her most important charac-teristic, that of safety at all times and in all con-ditions. "

Speaking of the increase in size, Mr. Cramp thought on a basis of 28 ft. draught a beam of 70 ft. could be used, with moulded depth of about 50ft. and length of 600 ft. to 620 ft. He argued that for more than 12,000 horse-power you must have two screws, and for over 24,000 horse-power three screws. He closed with the following :

"We are, as is well known, building a couple of 536-ft. ships for the International Navigation Com-pany. They are both framed up about two-thirds of their length amidships, and plating is in progress. They will be launched next spring, and will go in commission about a year from now.

"Their principal dimensions and qualities are as follows :

L ength on load-water line... 536 fb. Length over all ... .. . 55t , Rx.treme breadth .. . ... 63 , Moulded depth .. . .. . 42 , Gross register ... ... About 11,000 tons First ea. bin capacity . . . 320 passengers Second cabin capacity ... 200 , Third cabin capacity .. . 900 ,

'' Their propulsion will be by twin screws, ac-tuated by two quadruple-expansion engines on four cranks, which, with steam at 200 lb., will prol)ably develop about 20,000 collective indicated hors~power. To support the outboard shaft bearings, the hull is built out in a. horizontal web to a steel frame having both bosses cast in one piece, and weighing about 68,000 lb. The after deadwood is cut away, and the keel slopes up so that the shoe meets the boss frame at the after end. It will be observed that these ships are considerably larger than the New York and Paris, or about half-way beteen them and the Campania class. I will not venture a prediction as to their probable perform-ance, but I will guarantee them to be perfectly safe, comfortable, and economical ships.

'' These ships are American from truck to keelson; no foreign material enters into their construction. They are of American model and design, of American material, and they are being built by American skill and muscle. "

The author's remarks were received with great applause, and some discussion followed.

The next paper wa.s read by Naval Constructor J. J. Woodward, U.S.N., and treated of the "Determination of the Approximate Dimensions of a V easel to Fulfil a Given Programme of Require-ments. " It was also followed by a debate. But the paper was mathematical, and discussed the methods and formulas used by our naval con-structors. The author thought our designers were hampered for want of a. tank in which various models could be tested.

(To be continued.)

THE SEW AGE DISPOSAL WORKS OF THE COLUMBIAN EXPOSITION.

ONE of the great problems presented for solu-tion to the World's Fair authorities was the dis-posal of the refuse constantly accumulating . a.t Jackson Park, equivalent to the sewage of a City

of 150,000 inhabitants. It was necessary to adopt a separating system, so that a pure effluent could be discharged into Lake Michigan, for none of the city sewerage was available for the purpose. A complete sewage purification plant was therefore required, and at this plant Mithe sewage from the Exposition buildings was purified by means 0f chemical precipitation on the continuous plan, the plant being modelled after t hat at Dortmund, Germany, designed by Mr. Carl Kinebuhler. The Chicago plant was located in the south-east corner of the grounds, near the stock exhibit, and close by the car and power house.

A general plan of the purification works is shown by Fig. 1, and a combined elevation and section of the tanks by Fig. 2. From these two figures it will be seen that the plant consisted of an elevated receiving and distributing tank (see F;g. 3), four chemical mixers, four precipitating tanks, two boilers, a 50 horse-power engine, two air compressors, three sludge r eceivers, two sludge filter-presses, two pumps, and other accessories, all inclosed in one building. The building containing the plant was 100 ft. by 125 ft.

The main outlet sewer terminated in a vertical standpipe 3 ft. in diameter and 40 ft. Of in. in height, which extended nearly to the top of the re-ceiving and distributing tank, shown in section and detail by Figs. 5 and 6. This standpipe was made of !-in. tank steel, riveted in 5-ft. lengths with !-in. rivets having 1! in. pitch, the seams lapping 1~ in. The pipe terminated in a bell mouth riveted to the top of the standpipe, and the top of the mouth was secured as shown by detail, Fig. 6.

The receiving tank (Figs. 2, 3, and 5) was 16 ft. in diameter and 10 ft. high, or 8! ft. high to t he top of the grating, which gave a capacity to the latter point of 12,750 gallons. Like the stand-pipe, it was of !-in. tank steel, with 1! in. lap at the joints and !-in. rivets with 1t in. pitch. The sewage discharged from the bell mouth of the standpipe on to a grate screen 18 in. below the top of the tank. This screen was in eight sections (see plan, Fig. 4), and was made of ~ in. by lt in. bars on edge, spaced 1 in. centre to centre, as shown in the partial plan of the grating (Fig. 4), and by t he details of the long and short grate-bars (Figs. 7 and 8). The sewage passed down through the grate-screens and from the tank through any or all of the four outlets E, E, shown in Fig. 2 on the section of the tank (Fjg. 5), and also in detail in Figs. 9 and 10. Each of the outlet pipes was 14 in. in diameter , and was controlled by a gate.

Sulphate of alumina. or copperas was admitted to the sewage as it flowed through the outlet pipe from the diBtributing tank, as shown in Fig. 2. The chemical was thoroughly mixed with the sewage by the machine mixers located in the special device in the outlet pipe, and shown in detail by Figs. 12 and 13, after which lime was admitted to the out-let pipe and a further mixing of sewage and chemicals secured by means of the mixer, shown in the plan, Fig. 11, in the section, Fig. 2, and also in detail by Figs. 14 to 16. The outlet pipe terminated a.t the cone mixer in a quarter bend of !-in. wrought iron bolted to the pipe by means of a wrought flange with an 18!-in. bolt circle having 16 bolt holes f in. in diameter. The cone mixer was suspended in the central cylinder of the pre-cipitation tanks by hangers from !-beams, as is shown by Fig. 2, and in detail 1y Figs. 14 to 16. This mixer discharged the sewage over its top edge down the central cylinder to be dis-t ributed by horizon tal arms throughout the lower part of the tank, after which it rose to the top of the large tank and passed out in a clarified state, t he solid matter meanwhile having been precipitated to the bottom of the tank, from which it could be drawn at any time to the sludge receivers and filter presses.

The central cylinder (see Fig. 2) was 6 ft. in diameter and 32 ft. high, made of -itr in. by 60 in. plates. At the lower part the sewage was distributed downward into the conical-shaped bottom of the main precipitation tank by means of eight horizontal radiating arms consisting of inverted V-shaped troughs supported at the outer ends by t-in. rods from the central cylinder, as shown in the section, Fig. 2. After the sewage had passed down through the central cylinder and up through the main part of the tank, the offiuent was collected at the top of the tank by means of a system of suspended wooden troughs resting on the top of the clarified sewage, as shown in detail by the various plans, elevations, and

s~ctions in Figs. 1 , 2, 17, 18, and 19. The trough~ from each pair of tanks led t o a common effiuent standpipe. 12 in. in d iameter, which conveyed the effl uen t d own to t he g round , where i t passed through an outlet p ipe to t h e lak e.

The p recipitating tan ks wer e 32 ft . in d iameter for the fi rst 32 ft. from their top d own, and then diminished in the form of a cone for 22 ft. t o a. diameter of 6 ft . , making their t ot al height 52 ft. The effiuen t t roughs wer e 18 in. below the t op of the tanks, leaving the available h eight of t h e circular par t of the tank 30! f t . A llowing for waste space, th e available capacity of the tanks may be tak en as 237, 000 gallons, of which abou t 54,000 gallons was afforded by the conical portion of th e t ~nk. Of course i t will be understood that t he h old ing capacity of t hese t anks d oes not direct ly indicat e their service capa~ity, the t reatmen t being cont inuous.

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Some of the d eta ils of riveting and supporting the conical part of t he tanks a re sh own by Fig. 20. The pile and t imber foundations of the tanks are shown in Fig . 2 (most plainly on the left). There were three concen t ric rows of piling, thirty in each row ; they were p laced 30 in. apart centre to centre, one beneath and one on each side of the outer edge of the tank.

The sludge pipes started from the b ottom of the precipitation tanks, and extended upward and out of the tanks, as sh own in Fig. 2. The lower end of each pipe terminated in a bell m outh supported on three legs, as shown in detail by Fig. 22. E ach pipe was 6 in. in diameter, and connected with a 6-in. pipe leading t o the three sludge tanks or receivers, as shown in Fig. 1. The detail of the sludge pipe at i ts passage through the conical bottom of the tank is also shown by Fig . 21. The three sludge tanks were each 4 ft. in diameter , and 8 ft. high in t he clear, the ends being curved outward, giving a capacity of about 100 cubic feet, or 750 gallons. The sludge passed in at the top and out at the bot tom of t he t ank through a special casting (Fi?. 23). Compressed air was admitted through a 2~-in. air pipe entering the top of the tank. A hand-hole was provided in the top of the tank, and a float and indicator to show when the tank w~s fu11.

Upon opening the proper gate in the sludge pipe connecting the precipitation tanks with the sludge

E N G I N E E R I N G. t anks, the sludge was forced t o the sludge tank by the head of sewage above it . When the sludge tank was fill ed, compressed air was turned into it, and the sludge was forced into one of the two fil ter presses, sh own in plan by Fig. 1. Each fil ter presJ h ad rl fty cells, 36 i n. in d iameter and I ! in . thick. Each sludge cak e weighed about 47 l b., and each pressful of sludge about 2350 lb. The presses wer e made by t he .Perrin Company , of Chicago, which manufacture filter presses for separating g rease at packing houses, t o which these are simila r. The ironwork of the presses was made by the G. H. Bushnell Company, of Thompson ville, Conn. A tramway, sh own in Fig. 1, was provided for removing the sludge cakes to the Engle garbage crematory, si\uated just east of the disposal works. The two vertical boilers, shown on the plan, Fig. 1, were each of 40 horse-power, and, ltke all the boilers on the grounds, were oil-fed .

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The 50 horse-power high-speed s team engine was made by the New York Safety Power Company. By means of a belt the engine drove the line shaft, which in turn transmitted power to run an elevator, a pulveriser which ground clay for earth closets, the four chemical mixer~, by means of r ope trans-mission, and three centrifugal pumps. The two air compressors were put in by the Norwalk Iron Works Company, South N orwalk, Conn., and had 8 in. by 10 in. steam cylinders. The Worthington pumps, as ahown on the plan, Fig. 1, were used to pump the local sewage of the disposal building, including the liquid from the presses to the tanks, and were also used to empty the tanks. The h eavy flow of sewage, as would be expected, was from 9 A. M. t o 6 P.M. \Veir measurements of the effiuents were taken every hour, and both chemical and bacteriological analyses were made to determine the results obtained. The plant was put in operation on April 14, 1893. The average dc1ily flow of sewage since the beginning of May was as follows :

Gallons. Moo th of M a. y .. . 9!0,000

" June ... . .. ... . . ' 1,630,000

, July . . . . . . . .. 2~21G~COO , August ... . .. . .. 2,497,000 , , September .. . ... 2,425,000

First week in October .. . ... . .. 2,358, 000 Second week in October ... ... 2,5821000 Chicago Da.y, October 9 . .. . .. 2,935,000

Experiments were made with copperas, sulphate of alumina, and lime, as precipitating agents. 'Ihe plant was operated with e jght-h our shifts, and e~h shift was instructed what chemicals to use and In what quant ities. The morning shift incl';lded an engineer, a fireman , and a pressman, w1th two helpers, and a. man to a t tend to the screens, the chemicals, and t o t ake the weir meas urementE-a t otal of six men ; from the afternoon shift the two labourers were omitted ; and, on the night shift, only an engineer, a fireman, and a chemical tender were employed . As each of t he four tanks could be operated independently of the others , it was possible t o use different kinds and amounts of chemicals with t he ~a.me sewage. The cost of the chemicals was ab0ut 8 d ols. per 1, 000,000 gallons.

The cost of the installation, exclusive of the building, was about 32,500 dols. The plant was b uilt under the direction of W. S. MacHarg, eng ineer water supply, sewerag e, and fire protec-tion. Mr. C. E. Chester was in charge of the mechanical portion of the work, and the chemical treatment was in charge of Mr. Allen Haze n, of the Lawrence Experiment Station of the ~Iassachusetts State B oard of Health .

A DDITIONS TO THE NAVY.- The Naval Construction and Armaments Company have received orders from the Admiralty to build three torpedo destroyers of the Ha.vock type. These boats have a. displacement of 230 tons, 4000 horae-power, and a guaranteed speEd of 27 knots. They will be fitted with water-tube boilerl', the patent of Mr. Blechynden, engine works manager of th 3 Barrow works. The dockyard authorities at S heerness ha.ve received in-structions to proceed with the building of the new station gunboats Torch and Alert, which a.re provided for in the Na.vy E stimates of the current financial yea.r. It is pro-posed to build the vessels side by side in No. 2 dock, which ha.s been found just wide enough to admit of their construction. The Torch a.nd Alert belong to an en-tirely new cla.sa of gunboats, and will be built from the designs of Mr. W. H. White, C.B., Director of Na.va.l Construction. ThE> are to have a. length of 180ft., a breadth of 32ft. 6 m ., a.nd a. mean loa.d draught of 11ft . 6 in. Tbey will have a. displacement of 960 tons, and will be fitted with maohinery of 1400 horse-power under fcrced draught and 1050 horse-power under natural draught, with a. speed of 13.25 knot::J a.nd 12.25 knots re-sp~ctivel,Y. Thell' a.rma.mez;tt ~ill consist entirely of qUlckfirmg guns, each carrymg s1x 25-poundera and four 3-pounders.

L ONDON ASSOCIATION OF FOREMRN E KGINEERS AND DRAUGHTSMEN. - The usual monthly meeting of this Association was held in the Cannon-street Hotel on Saturday, the 2nd inst., when the President, Mr. W. S Coa.tes, occupied the chair, a.nd Past-President Mr. J. E. Bart.le was in the vice-chair. Among other business constdered was a. report by the committee recommending the disposal of a. quantity of ~he older books in the library, to ma.ke room for more modern a.nd useful works which wa.s agreed to. After the ordinarr. business wa.,; finished, a paper wa.s read by Mr. J. G. Gtbbon, a. former member of the Association, on "Reclaiming the Fore-shore of the River Thames. " Mr. Gibbon stated tha.b the arguments in favour of this were usually under three ?,ead~-first, "to find work for the ~me.mployed ;"secondly.

to Improve the health of the dtstrtcts near the river " and thirdly, "to improve the trade of the Port of London~, but he di~ not think it would be likely to do either. He thought tb very doubtful whether many of the olass of ~en who are out of work would be employed in reclaim-mg the foreshore, a.s such an undertaking would probably be lE't to contractors, who would employ men accustomed to that class of work. With reference to the second argument, he did nob think there was much in it a.s alt~oug~ Poplar ha.s. the largest river frontage of' any pa.nsh m L ondon, 1ts dea.th-ra.te is lower than Bow which is more inland ; and since the new sewage work;

~b the outfa.lls ha.ve been in full operation, a marked Improvement has taken place in the condition of the foreshore~ of the river. 4s there were many entrances to docks, shpways, &c., whtch would ca.use brE>aks in the

e~bankment, there would be largb deposits of mud oppo-~tte those entrances; the narrowing of the channel would mc~ease the cu~rent and the difficulty of navigating. whtle the reduct10n of the width of waterway would tend to _crowd t~e centra more, and so iucrea.se the risk of ~ertou~ accidents. ~he cost of such an undertaking, mcludmg compensatton to J?resent occupiers of riverside property, would probably mvolve an annual charge of not less than 600,000l., which, added to the present _port

ohar~es, would very. s_erioutt~y handicap the Port of Lon-don 10 the competttton w1th other ports for shipping trade. He thought, therefore, it would be a mistake to emba.nk the r~ver above Woolwich; but that it might be an advantage 1f a.n arrangement could become to between the vestries and the County Counoil to send the dust and other refuse down. t~e river in large barges, mix it with sewage, and depostt 1t on the low lands in the lower reaches o~ the river, where it would soon become good soil, and g1ye employment to numbers of people to cultivate and ratse prfitabl~ and useful crops upon it. A discussion ensued, m whiCh seyeral mem~e~s took part, and a. vote of thanks t_o Mr. Gtbbon for hts mteresting paper closed the proceedmgs .

E N G I N E E R I N G. [DEc. I 5, I 893.

DOUBLE-CYLINDER STEAM FIRE ENGINE FOR CALLAO. CONSTRUCTED BY THE FIRE APPLIANCE) :MANUFACTURING COlYIPANY, LIMITED, NORTHAMPTON.

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WE illustrate above a. steam fire engine constructed by t he Fire Appliances Manufacturing Company, at their Vulcan Works at Northampton, for the Callao Fire Brigade, Peru, whither the engine has just been shipped. The engine, al though of the standard type of the company- the Vulcan type, siz~ No. 7-with double cylinders and pumps, differs in general design from t he steam fire engines usually adopted in this country. It is mounted on a crane-necked frame, provided with laminated springs, steel axles, anci wrought-iron wheels with polished steel hubs. The design of the crane-necked frame permits of the locking of the large fore wheels. Brackets are provided on each side of the engine t o carry two 10-ft. lengths of suction hose, one on either side. The fore car-riage is fitted with a windlass, with drag ropes for manual haulage.

The boiler is constructed entirely of Low Moor iron, with welded shell, and is of the vertical cross-tube type, similar to those in use by the Metropolitan (Lon-don) Fire Brigade. It is stoked from behind, and fitted with the usual mountings, and covered with orna-mental, highly-polished brass lagging. The steam cylinders are two in number, cSLst t ogether in one piece, and fitted with steel covers and pistons. The piston-rods and motion work are entirely of steel. The pump valves and pistons can be readily examined by removing six nuts. The engine is also fitted with a. swivel suction-bend, so that the suction can be led away from either left or right of t he engine. Two feed pumps are provided, a~d are worked. from_ the crankshaft, feeding the holler on oppos1te s1des. The diameter of the steam cylinders is 8! in., that of the pumps 6 in., and the stroke ~ in. . The engi~e, running at an average fire speed, 1s des1gned to dis-charge 400 gallons of water per minute through five jets. .

The engine has been purchased by the Compagma Italians. Pompeiri Italia,. the leading fire brigade i? Callao, Peru, in celebrn.t10n of the twenty-fifth a.nm-versa.ry of the brigade, and has been named the "Fra.ncesco Toso," in commemoration of the foun~er of the institution. This type of engine has met w1th much favour in South America., where they have

been hitherto accustomed to engines of the horizontal type.

The engine ha.s been tested by a.n engineer sent over from PHu for the purpose, and he has expressed him-self highly satisfied and pleased with the way in which the contract has been executed.

HYDRAULIC PASSENGER ELEVATOR. THE hydraulic passenger elevator, illustrated on the

opposite page, was exhibited at the Columbian Exposi-tion, and is of the high-speed type, constructed by the Ea ton and Prince Company, of 70 to 76, Michigan street, Ch icago. The mechanism is placed in the cellar, and is of the usual pattern, with multiplying pulleys. The car is stopped and started by means of a lever, instead of the man grasping the hand-rope directly. The water supply to the hydraulic cylinder passes through the valve shown in Fig 2, which gives a very easy mot ion in stopping and starting, and pro-duces no shock. At the top and bottom of the car 's travel the cross-head of the ram operates a special valve to cause the motion t o cease, an arrangement that puts the passengers' security beyond the care of the attendant and the integrity of the hand-rope. This latter valve-or rather valves, for there is one in the supply pipe and another in the discharge-pipe-is shown in the upper part of Fig. 2. The two valves are on one rod, and block one passage or the other, accordingly as they are drawn to the right or left. The supply water comes through t he left passage, and, entering the lower valve case, turns to the right. If the lower valve be open (it is shown closed), the water passes through openings in the brass liner into the bulbous swelling which is in communication with the hydraulic cylinder. When the lower valve is moved to the left, the supply water is first cut off, and then, as the motion proceeds, the hydraulic cylinder is placed in communication with the dis-charge pipe. The valve stem carries two extra pistons, besides those forming the valve, in order that it may be always in equilibrium. It also carries a. controlling piston, to render its movemant easy and gradual.

Figs. 3 to 7 show the governor. The pulleys run in

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STANDARD ROLLING STOCK ON THE VICTORIAN RAILWAYS.

\VITH a view to facilitating maintenance a.nd economising in the cost of repairs , a complete set of standard designs of rolling stock has been adopted on the railways of Victoria, and all fnture engines and vehicles will be constructed upon these lines. The older stock, which is of varied types, will also be gradually replaced by those of standard form as time goes on. All passenger stock (whether old or new) is fitted with the Westinghouse automatic brake; and all new goods wagons are also supplied with the "quick-acting " 'Vestinghouse. The whole of the stock, it should be noted, is of Victorian manufacture, having been built to the designs of Mr. A. D. mith, the loco-motive superintendent, but in this article we propose to deal only with locomotives, reserving our descrip-tion of the carriages and wagons for a future issue. \Ve may, howe,er, in passing call attention to Figs. 1 to 4 {see page 732 and our twopage engradng), in which the general features of every one of the etandard forms of engines and carriages are shown, with the ex-ception of the D class, light line engine, which, however, closely resembles both in general appearance and in de-tails of construction the A class engine shown in Fig. 4. Coal is used almost exclusively as fuel , the great danger of bush fires, resulting from wood combustion, pre-cluding its use; to minimise t he risk of fires as far as possible, all engines are fitted with spark-arresters, or screens, consisting of iron rod grids placed in the smokeboxes, and enveloping the blast pipe3 and connecting them with the chimney opening. As will be seen from Figs. 1 t o 4, and from the more detailed views of engines A, Y, and E (Figs. 5 to 9), the locomotives are essentially British in design, having copper fireboxes, brass tubes, plate frames, and, in the case of the bogie engine, the bogie itself is built on British lines.

Class A engine (Figs. 5 and 6) is designed for the

ENGINEERING, DECEMBER 15, 1893.

STANDARD TYPE LOCOMOTIVES FOR THE VICTORIAN GOVERNMENT RAILWAYS.

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long-distance intercolonial traffic, and is a powerful t ype of express engine, having cylinders 18 in. in diameter by 26 in. stroke. It has two coupled driving wheels 6 ft. in diameter, and a four-wheeled bogie in front wi th 3 ft. G in. wheels. The boiler is 4 ft. 4~ in. in diameter and 10 ft. 6 in. long between tubeplates. The tubes, 212 in number, are of brass, and are 1l in. in external diameter. The firebox is of copper, and has the roof supported by radial stays. The heating surface is 1151 square feet , of which 1050 squ are feet are tube surface. The grate area is 21 square feet. The cylinders are placed between the frames, with the valve chests arranged between them. The gauge of the Victorian lines being 5 ft. 3 in., this does not necessitate such close packing as is necessary in stan-dard gauge engines of similar-sized cy linclers. The re\Tersing gear is of the ordinary tephcnson link t ype. The engine has in working order a total weight of 43 tons 12 cwt., of which 29 tons 4 cwt. are concen-t rn.ted on the drivers. Its total estimated tractiYe power is 11,700 lb. The t ender designed to accompany this engine is of the mmal six-wheeled type, and is designed to carry 2200 gallons of wat er and 70 cwt. of fu el. Its weight in working order is 28 tons 14 cwt.

lass Y engine (Figs. 6 and 7) is an ec1 ua1ly power-ful goocls locomotive. Like the A type, it has inside cylinders 18 in, in difl.m~ter by 26 in. stroke, The

boiler, t oo, is almost identical in construction, the principal dimensions being the same, though the different arrangement of wheels has necessitated some slight differences at the firebox encl. The number of tubes, heating surface, and grate area a re the same for the two classes, though there is a slight difference in weight, Class Y weighing 40 tons 9 cwt. , all on, as compared with 43 tons 12 cwt . for the A type. The tractive power of the Y t ype, owing to all its weight being utilised for adhesion, and its smaller drivers, is, of course, greater than that of the A engines, viz., 15,600 lb., as against 11,700 lb. The same tenders are used for both classes of engine.

Class B (Figs. 9 and 10) is of a less powerful type than either of the foregoing. It is a side tank loco-motive, intended for suburban and similar passenger t raffic. It has inside cylinders 17 in . in diameter by 26 in. stroke, and has four coupled drivers 5 ft. in diameter. The boiler is 10 ft. 6 in. long between tube-plates, and is 4ft. 2 in. in diameter. The tubes, as before, are 1! in . in external diameter. The fire-box is smaller than in the case of the engines already described , the grate area being 17.8 square feet. The total heatiog surface is 1054 square feet, of which 97 1 sqnare feet is in the tubes. The weight of the engine in working order, with 1300 gallons of wa ter in the ta.nks7 and 5Q cwt, of cot\l ou board, is 50 tons

6 "cwt., of which 32 tons 4 cwt. is available for adhesion.

As already mentioned, all the rolling stock is colonial-b~ilt. This is done no~ in the railway shops, b.ut by pnyate fin~s; the destgns, as already men-ttoned, bemg furm~hed by the locomotive superin-tendent. As, however, the engiues already number upwards of 500, and the ca rs of various types nearly 10,900, large works are required for the repair a.nd mamtenance of these. For this purpose extensive new works have been erected at Newport, some five miles from Melbourne, where an area of 147.5 acres has been laid out in workshops and stores. On this space buildings covering an area of 8 acres have been erected at a. cost of 160,000l., t o the designs and under th~ supervision of Mr. A. D. Smith, the locomotive super-intendent. In the various departments of the works about 1250 men are on the average employed. The buildings at present completed consist of three main blocks, viz., the central, east, and west blocks and a tarpaulin factory. The central block, as its ~ame implies, is situated between the east and west blocks from which it is separated by clear intervals of 46.5 ft: This block, which has a frontage of 1034.75 ft. and is 294.5 ft. deep, is subdivided into offices (semi-detached) stores, patteru a.nd coppersmiths' shops, and bl'a.s~ foundry, to which will shortly be added ~n ifon

E N G I N E E R I N G.

DIAGRAMS OF STANDARD ROLLING STOCK : VICTORIAN RAILWAYS. - 40 ruT -c """ - - HOO:lC eO"

DEc. 1 s, 1893.] by G. 5 ft., fitted with a 25- ton steam ha mmer rolls and all other a pplia nces necessary for t he productio~ of blooms from scrap and their convers ion into bar &c

The ta.rpaulin shop has a floor space 91ft. by 7 .5 ft.: bu~ ~ co~tract ? as bee n concluded for an exten s ion whtc:l wtl_l e~ns tderably inc rease its length. The pre-sent cJ.pa.city 1s equal t o an output of 500 new tarpa ulins

pe~ ~onth . The sides are constructed up on the louvre prt~?Lple, to allo_w of a thorough through draught, to f~cthtate. the dry10g of ~he wa_terproof varnish (having lmseed o tl ~s a base) w1t h wb1ch the can vas is coat ed . After coatmg u pon the concrete fi0or, the shee ts are snsp_end~ 1 from the roof by snita ble tl.ck le until dry. ewmg ts p crfor'!led b y_ four doub~e and two s ing le n eetlle l~eavy ~pectal sew10g machine~, r un from a. line of sho.ft mg dr1 ven by a 10 horse-power engine.

( ro be continued.) CA K-MAKING MACHINERY

AT the ordinary m eeting of the Ioqtitutio~ of Civil Rogmeera, held on Tu~sday, J?ecember 12, Si r B enja.min Dl>ker, K .C. ~ G , y1ce~~restdent, in the chair, a. pa.per was rea~ d eahng w1tb Cask-Making 1\Iachinery," by Mr. L 9 WlS II. Ra.nsome, Assoc. M. Ins t . C.E.

The ch_ief d ifficulties t o be overcome in the application of machmery to th~ ma.nufa~ture of barrels were ata.ted t o be, first, the d1ff~rent. s1zes and varying shapes of barrels :. second, t_he dtversJty of the materials employed; a~d, thtrd, the dtfficulty of working wood by machinery wtthout undue waste.

Casks might be _divided into three classes, viz. , slack cask R, used for holdmg ftour and ce~ent; semi-tight casks, for gunpowder, butter, &c. ; and ttght casks for liquids Th~ paper wM confi ned t o one type of slack ba.rrel that used for cement, and one type of tight the ope~ end. ready for the trus ing ~achine.

1s machm~ cons!s~ed of five dog , with steel clips attached. ~avmg a r1s1ng and fall ing motion, worked by a screw. ~be c~sk was plar.ed on the floor in the centre of the m_achme wath truss hoop3 on; the dogs closed again&t the stdes of t~e cas~, . and, descending, drew down the tru~s hoop unt1l the JOtnts of the s taves were close a fter wbtch they were ~aused t o rise again, and the ope~ation was repea.t~d unttl all the hoops were in poaition. The next ma.c_hme ~o which the caek was taken was most valuab_le ID sav~ ng: labour, . as it performed the various operattons o! chmung, orozmg, and howelling both ends of the cask simultaneously, besides trimming off the ends. The cask was clamped b~tween two revol viug chuck~, and the cutter blocks, bemg brought into action s imul-t aneously, completed the opera.tion in a s ingle revolution.

The f~ces of t~e heads were planed, and the joints made wtth an ordma.ry hand-feed planing- machine and ~he dowel holes were bored by a small auger fitted mt_o the end of the planing spindle. The bead when fim hed must be . lightly oval, as the external pressure brought to be_ar upon it was considerable, and the wood was more eas1ly compressed, and a lso had a. greater t en-dency to. shrink oross'_Vise than end wise of the grain. The ovalhn~ and bevelhng were pffected in one operation the head bemg cramped between two ea. t-iron revolving pla;tes. T _wo cutter-blocks were employed, each carrying

kmves. whic~ cut the t op and bottom be vel and at th~ same t1me tr1mmed the edge of the head. The machine was. so arra.nged that the cutters always worked with the

gr~t? of th e wood, which insured a clean out. The dnvmg on ?f the permanent iron hoops was accom plished by hydrauhc power.

Tb~ chief obstacle to the introduction of cask-making machmery was th_e hosti_le. atti.tude of the coopers ; as ma_ny ma. ter~, while a~mtttmg 1ts great value, hesitated to tocur the mconvemence attending the s trikes wbic:h generally followed its introduction into works. I t had, however, been proved by pra.ctical results that casks could be turned out far more economically by machinery than by hand, and thP-re was li ttle doubt that before long hand made casks would be things of the past.

THE PHYSICAL SOCIETY. AT a mn~ting of the Physical Society, held on D ecem-

bFr ~ 1893! Professor A . W. R iicker, ~LA, F .R S. , Prestd~nt, m the chair, Messrs . .J. H . G illett and F . H ovenden were elected meD?Lers o f the Society.

A paper by 1\fr. J ames S wmburne, on "A Potentiometer for Alttrnat~ng Currents," was rAad by Mr. Bla.kesley. A fter referrtng t o the many advantages of the potentio-meter method of me~surement, the au thor d tscribes an arrangement by whteh alternating pressures can be

m~asured. A quadrant electrometer, with a. double fi h ta.tl needle susp~nded by .a torsionless fibre, is employed. The electrostatic attra.ctaon exerted by an alternating pressure between the needle and one pair of qua.drants is balanced by the force due to a steady pressure between the needle and the other pa~r of qua~rants. The magnitude of the st eady pressure 1s determmed by a potentiometer and. standard cell, and the effective value of the alter-natmg pressu.re thus_ded uced. For measuring alternating current~. a dtfferenttal _electrodyna.mometer, having t wo

~xed coi ls an~ one movmg coil, and no controlling spring, ~~ used. A dtrect c1;1rrent, measured by the fall of poten -tta.l over a small res1stance, is passed through one of the fixed c~ils, the alternating current through the other fixed cOil, and the moving coil is included in both alter-nating and direct current circuits. When the two forces

~a.lance, t~e curren~s are taken as equal. Several small ma.ccura.Cies t o wh10h the method is subject are men-tioned in the paper.

ProfessorS. P. Thompson inquired if the fishtail-shaped needle o f the electrometer was n ovel.

Mr. Blakesley said the author had mentioned the needle r.reviously. He (Mr. Blakesley) thought the name 'potentiometer " was not very suitable. In effect the

so-called measurement of pressures wa.CJ a. compa.ris~n of two powers.

The President announced that Mr. Preeoe's note on the "Specific Resistance of Sat Water " bad been temporarily withdrawn.

Profe.qsor G. M. Mincbin, M. A ., made a. communica-tion on the "Calculation of the Coefficient of Self-Induc-ti on of a Oircutar Current of given Aperture and Cross-Section ." Ins tead of assuming the cross-section of the v:ire sm~ll, and the current densi ty constant over the sec-ti0n, as ts usually done, the author takes into account the dimensions of the section, and the n on-uniform distribu-tion of the current. Making use of the expressions for the vector potential {G) of the current given in his pre-vious papers (" Pbil. l\1ag., " April and August, 1893), the author calculates the total normal flux of force through a surface intersect ed once in the positive direc-tion by every tube of force emanating from the given curr~nt. This fl~x divi_ded by the current g ives the co-effiCient of self-mduot10n. 'l'he surface chosen is the circular aperture of the current, and half of the anchor ring formed by the wire. \Vhen the current density is inversely proportioned to the distance from the axis of the circular current, the value for the coefficient of aelf-induction is found to be

.,. { 4 a (L - 2) + 2 c ( L - ~) - 1~2 a (2 L + 19) } , where a is the radius of the central filament of the cur -rent, c the radius of the cross-section of the wire, and

rJ = loge ~ . c

After the cask bad been "raised," it was placed in a eteaming chamber until it was thoroughly soft and pliable. Clerk-1\faxwell's ap;>roxima.to exprers :on agreeJ with

this in the principal t erm. A s an example of the closen_ess of the approximation, the caEe of a cur-rent 10 a wire 2 millimetrPS in diameter bent to a. circle of 2 centimAtre3 mean diameter bad been taken, the approximate and corrected coefficien ts being 58.866 and 59.207 absolute units respectively. \Vben the current in th E! wire is superficial, as in case of alternating currents of_ hag~ frequency, the codficient is somewhao greater, bemg glVen by tl. e exprs~ ion

.,. { 4 a (L - 2) + 2 c ( L + i J + 1~2a ( 4 L + 11)} Incidentally it was pointed out that the function G.c

where G is the vector potential at A point distance x fron~ the a xis of a circular current was the same as , tokes's currer.t fufl,ction in hydrodyna.'mics.

An~the~ papa~, ~n t~e " Marmetic Field of a Currl'nt R-u;mn~g ut a Cylu~drt~al CCJi~, ". was read by Professor Mmchlr;t. The. cy hnd rtca.l coal IS regarded as a. seri e~ of equal otrcles lymg cl~se t ogether _and forming a cylindri-cal . surface. Rep~acang each Circular current by its

eqUival~nt mag~etic shell, the problem of finding the magnetic potenttal at a. point resolves itself into calcu-lating the g ravitational potential due to the circular

plate~ of a~tracting matt~r, one posi tive and the other neg:att ve, st tuatcd rcsl?ectt vely. at opposite ends of the cylmder . . The magnettc potent1al due to one plate is tb~n

deduce~ JD ~erms of elliptic integrals of the first, second, and tbtrd ~mds .. The_ Pre3ident bad pointed out that the expre_sstons gtven m the printed proof of the paper only applied when the perpendicular from the point t o the J?la.te fell within the circle; the author had. tbereforf', md1fied the formula so as to be true generally. From th1s formula. the equipotentia.l curves can be constructed. The same sys tem o~ curves serve ~or the plate at the other end of the oy_hnder by changmg the signs of the numerals representmg the potentials and giving the our_ves a _motion c;>f tr~nslatio_n equal t~ the length of the cylinder m the d~rectton of 1ts a xis. The equipotential curves for the cOil can then be deduced by drawing through the points of intersection of the two sets of curves .w~ose numerical values have a constant sum. In det ermmmg the curve , the author bad to calculate tables of elliptic integrals of the third kind, and these be hoped t o comple.te before the paper was published . In reply t o a questt?n on the first paper, which had been brought befo_re btm by Professor P erry, the au lihor said that as the dta!l'leter _of the wire _diminished indefinitely, both the self-mduct1on and re 1 tance became infinit~ but the ratio L / R became zero. It was interesting t~ exa~ine what ~el.ation ~etween the apertnr~ and cross-sectt~n gave mmuuum urpedanc:e. If the ordinary ex-presston for L be taken, the problem was impossible but the corrected form admitted of a solution. '

Professor P erry ho~ed the work Professor Mincbin had done so ~ell . for CI~cles and cylinders would be ex-tended t o _cyhndrtcal co1ls of rectangular cross-section. lb was most 1mportant t o be able to find the shape of the fi eld produced by such coils.

Professor S: P. Thompso~ inquired if there was any way of deducmg the expressiOn for the magnetic force at a. P?int _other than . that given in the paper on the " l\Iag-nettc Field of a Ctrcular Current" C' Phil. l\Iag. " April 1893). , ,

In reply, Professor Mincbin explained how the formula. followed at once from the fundamental theorem that magnetic force is the work of the vector potential. This was based on La place's ex prassion for the force between a. magnetic pole a.od an element of current which had been proved experimentally. '

~TREET RAILWAYS AT SAN FRANCisco.-An effort is bemg mad~ to place the whole of the street railways of San Fra.nCis~o ull;der one manag_ement. With this object a company 1s bNng formed, w1th a. proposed capital of 3, 600, OOOt .

A MERICAN RAILROAD PROP&RTY.-America.n railroad property appears to have become, upon the whole less pro-ductive during the last five years. In 1 7 the ~ggregate

leng~h of line worked was 13G,989 miles; the revenue acqmred was 931,385,154 dols., and the n~t income realised

~as 331,135.676 dols. In 1892 the aggregate length of hoe worked had increased to 170,607 miles the rough revenue acquired was 1, 191,857,0!)9 dols. but the net profit realised did not exceed 352,817,405 dols. In other words, while the net receipts per mile worked were 2141 dols. in 1887, the corresponding return in 1892 did not exceed 2068 dols. per mile worked.

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0 TAGO CENTRAL R AlLWAY.-Tbe works on this line have been energetically proceeded with. The earthworks between Middlema.rch and Hyde may be regarded a.s practically finished, and the masonry abutments for most of the bridges have also been erected. The contract for the manufacture of the iron superstructures of the bridges was let to Messrs. Anderson, of Cbristchurch, in Decem-ber, 1892; to expedite the work a bonus was offered to the contractors for the completion of their contract before t _he specified time, and the girders are now being de-livered ; as soon as possible after their erection plate-laying will be proceerled with. The bulk of the sieepers are already in band. Con tracts for the supply of the balance have been let, and all the rails and fastenings req o1ired are in store at Dunedin. The New Zealand Government hopes t o ba able to open the new line for traffic to Hyde in the early part of next year. It is proposed to at once proceed with the nonstruotion of the section between Hyde and Eweburn, a. distance of 21 miles 67 chains. An extension of the line to Eweburn will promote settlement, and will materially assist in openin~ up Central Ota.go.

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DOUBLE PLATE PLANING MACHINE. CONSTRUCTED BY THE NILES TOOL \VORK S COl\IPANY, IIA~fiLTON, OHIO, U . . A.

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forming a diaphragm to create a circulation from the extreme upper ends of the car to the ice chamber, as shown to the right of Fig. 1. Over this ! in.

by~ in. strips are nailed on the sides of the carlines at a height of 3% in. from the bot tom of the carline to the top of the strips. The space to the top of the strips is then filled with ground cork. On the top edge of theije strips a line of twine is tacked, over which comes a course of g-in. sheathing. This is covered with one thickness of "P and B " three-ply paper, the paper turning up on the ca.rlines and being secured by strips placed over it and nailed to the carlincs. The spaces between the carlines are filled with ground cork. On the top of the carlincs, the ridge pole, and the plates, a line of twine is nailed, followed by one thickness of paper, then another line of twine is put in place, on top of which comes the lower course of roofing. The whole is surmounted by a '' Drake and \V eir " roof.

Coming to the floor of the car, the insulation of this has been done with equal care. Commencing a.t the bottom of the sill, on each side of the centre and intermediate, and on the inner side of the outside sill, A in. by 1~ in. strips are nailed. On top of these strips comes a line of twine, as before, followed by a floor of g-in. pine, then a second line of twine and one thickness of "P and B " three-ply {>&per, turning the edges up 1~ in. on the sill. Over this is nailed another