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MARINE REVIEW. 1 Water-Tube Boilers for: Cargo Steamers. The following paper read before the conference of the institution of civil engineers in England will,answer many of the objections urged against water-tube boilers for cargo' steamers. The water-tube boiler first appeared in America in the very early days of this century, long before QueenVictoria ascended the British. throne. The object of Colonel Taylor, in 1807, was to substitute for the heavy, roomy, and somewhat inefficient Cornish boiler a genera- tor more suitable to the exigencies of. shipboard, and that after ex- perience with the paddle-steamer Claremont on the Hudson. It will thus be seen that at the outset the distinguishing features of a water- tube boiler --viz., light weight and small-space occupied--operated to cause it to be proposed in the mercantile marine of America. Many efforts have since been made in America to employ a water-tube boiler of some kind or other in mercantile*Ships, so that to-day the engineers of the United States are in a much'more receptive mood for the adoption of the water-tube boiler than are the engineers of this couutry, where hitherto the attempts to'wSe that form of boiler at sea have been few and far between, and mostly, attended with ill-success. In H. M. navy, experiments with bath the Belleville and Thorny- croft boilers have shown that the type ea Be worked as economically as to fuel as the Scotch boiler, and that' the amount of coal required to get up steam is considerably less. Thi te is indeed no prima facie reason why the water-tube boiler, properly designed and properly worked, should not be capable of evaporating as much water froma pound of fuel as the ordinary boilér ¢an. The prime cost of the Belleville boiler is undoubtedly very much greater than that of the best cylindrical boilers, and it is probable that every kind of water tube boiler in which so much screwing and so much accuracy of fitting is involved, and for which so many special fittings are required, will always exceed the cost of the old type of boiler; but the Babcock and Wilcox boiler, and boilers of the type:in which the tubes are simply expanded in place, and for which no special appliances are necessary either for circulation or for fuel burning, cost little or no more than the ordinary boiler. Experience with both the Belleville and the Babcock boiler has shown that defects and mishaps may be remedied at sea by the vessel's own staff, and that mishaps of a more serious nature can at comparatively slight expense and in a short time be effected in port. : With existing designs of water-tube boiler, a little more care in stoking is necessary, especially if the best results from thé fuel are required; but there is nothing so serious as-to prevent the ordinary every-day marine fireman from being educated in a few hours to manage the fires of a water-tube boiler as well as he manages those of the Scotch boiler. From the conditions of employment in the mer- cantile marine this is lixely for some time to be a difficulty; still it is not an insuperable one, and, if ship's engineers will take the proper precautions, need not be one of long duration in any ship. The shipping of the mercantile marine may be roughly divided into (1) passenger steamers pure and simple; (2) cargo steamers carry- ing passengers; and (3) cargo steamers pure and simple. The passen- ger steamer must necessarily be a fast one, and is usually of fourteen to twenty-two knots speed. Its speed is dependent on its form and the power its machinery can develop. "Without the fine form the largest power is unavailing for speed, and without the necessary power the fine form is useless, Fineness of* form means minimum of dis- placement, and consequent minimum. weight of hull and machinery. Great power means great weight; therefore in this class of ship every- thing is resolved into a question of weight. The hull of the vessel has to be designed and constructed in accordance with the rules and regu- lations of registries and the Board of Trade, which circumscribe the designer. The engineer in designing 'the: machinery is similarly fet- tered; but he can, by causing a small engine to work at a large num- ber of revolutions, and by skillful 'design, considerably reduce the weight per I.H.P. The great item of weight, however, is the boiler and the water contained in it. Consequéntly, by changing from the heavy Scotch boiler, with its mass of water, to the lighter water-tube boiler, with its small quantity of water; much more horse-power can be developed in the ship, or her lines may be fined, or there may be Modifications in both directions with pethaps the best results, Large numbers of passenger steamers are on short service, making daily or nightly runs of a few hours at a time, Steam being raised on each oc- casion, and lowered when done with. The water-tube boiler accom- Modates itself admirably to this; and"not only so, but seeing that steam can be raised in half an hour, the boiler-room staff of:such a boat can have ample rest between the runs, besides requiring only a small consumption of fuel to raise steam, so that even if the boiler when running is not so economical as the Sentech boiler, the total re- sult of arun of a few hours duration is a consumption of no more coal. It is also necessary in passenger steamers that the running should be uniform. The water-tube boiler, with its very high pressure and reducing valve, permits of this, as the variation of pressure in the engine room is exceedingly slight. : at EN With the second class of steamers--namely, the cargo and passen- ger boat combined--speed is desirable, but it must not be on extrava- gant conditions. It is usually from twelve to fifteen knots; therefore any saving in weight by the adoption of a water-tube boiler would not be taken advantage of to increase the speed very largely by in- creasing the power, but it might, and probably would, lead to an in- crease in speed by the finding of the ends of the ship without loss of cargo-carrying power. If, however, the owners were quite content with the speed, they could effect a very considerabe gain in the in- creaséd cargo-carrying capacity obtained by the saving in weight of machinery, in some trades and in some ships the difference would often mean a useful margin of profit instead of a loss. In certain vessels of this class a saving in weight of boiler would permit of the carrying of a larger quantity of fuel, which might be bought at a cheap port, and enable the ship to return to a cheap port, instead of being obliged to purchase it at a dear one, as is often the case now, and this with- out disturbing the question of cargo-carrying, so frequently a nice point with ships of this class. Iu the cargo and passenger steumer in short trades, the same advantages in the raising and lowering of steam would be appreciated as in the passenger ship. In the cargo-boat, pure and simple, the water tube boiler does not make such a good bid for acceptance as in the other two classes; but it has still something to offer, especially to those of moderate and small size--namely, the advantages stated above for the cargo-passen- ger steamer. There are not lacking signs that the final adoption of the water- tube boiler in the mercantile marine will be preceded by the use of a mongrel form or combination of a water-tube and a tank boiler, and in some respects such a boiler is more tempting to the mercantile , engineer than the pure article. Such boilers would, of nece-sity, con- tain more water than the water tube boiler, pure and simple. and con- sequently would not evaporate dry in so quick a time in case of, the feed failing temporarily--a fear often expressed by practical sea going men. ; The Modern Marine Engine, The first ship having triple expansion engines to enter the trans- atlantic trade was the Martello, built in 1884 for the Wilson Line by Earle's Shipbuilding Company of Hull. Tuis ship was 370 feet long, of 43 feet beam and 28 feet deep. She had engines with cylinders 35, 50 and 82 inches in diameter and 57 inches stroke, carried 150 pounds working pressure, indicated 2,400 horse power and inade 12 knots on a consumption of 38 tons of coal per day. ny a In 1886 the North German Lloyd Company placed in service tle fine steamers "Aller, Trave and Saale, built by the Fairfield Company, with engine cyindlers 44, 70 and 108 inches in diameter and 72 inches stroke, thus being the first of the large passenger lines to adopt engines of the triple expansion type. ; The triple expansion engine being fairly established in popular favor, the commercial balance soon adjusted itself to the new condi- tions of greater economy of operation, and engine builders began to seek avenues for still further advancement which: naturally. took the direction of quadruple expansion. It was soon found, however, that. further advance by means of expansion in consecutive .cylinders _offered much less promise than in the past, and that, improvement was rather to be looked for in the use of various smal]l economies, hitherto neglected as profitless or impracticable refinements. The future of the quadruple expansion engine would seem to be largely dependent upon the perfecting of the water-tube boiler, as with the advent of a boiler.of that type which will exhibit such a degree of economy, durability and facility of repair as to secure its general adoption, one of the chief causes now tending against the use of the quadruple expansion system, namely, the difficulty of obtaining boilers which can be economically built and successfully kept in continuous service under the required high-pressure and temperature will disap- pear.--Charls E. Hyde in the Marine Number of Cassier's Magazine,