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8 Engines of 27-Knot British Torpedo Boat Chasers. The propelling machinery of three 27-knot British torpedo boat -- chasers, built by the Fairfield Ship Building & Engineering Co., Glas- gow, and named Handy, Hart and Hunter, are illustrated on this page. =~s The engravings are reproduced from Engineering of London. The boats are 194 feet long by 19 feet 4% inches beam and 12 feet 714 inches depth, their displacement in service trim being 245 tons. The engines are of the three cylinder triple expansion type, (other British firms have pre- ferred four cylinders with three expansions for vessels of this kind), and the cylinders are 18%, 27% and 42 inches diameter with a common stroke of 18 inches. All have piston valves. The cylinders are of cast iron, and with each was cast also the valve casing. The cylinder and casing bottoms, which are separate from the cylinders, are also of cast iron. The cylinder covers, however, are of cast steel and of light design, © while the casing tops are of rolled steel plate and dished to give the nec- essary stiffness. The pistons are of the conical or dished pattern, made from high-tension forged steel. The connecting and piston 'rods are made from forged mild steel and bored. The guide shoes, which are separate from the piston-rods, are of gun metal lined with white metal, and they can be readily adjusted. The guides, which are of cast iron, are attached, one at the top end to the cylinder bottom, the other to a crossbar midway down the columns, and itin turn is held in place by. the cross-stays. The valve gear is of the usual bar-link and double-ec-. centric description, the eccentric rods being made of mild steel with ad- justable gun-metal bushes at the top end. The straps are also of gun metal, and lined with white metal. The three-throw crankshaft is made from mild steel, and in, one piece. The body of the shaft and crankpins are 6 inches in diameter, Ha i SEN Ke Td ; ii Lees a 2 HUE i Ong MARINE REVIEW. nes an ae oR 5 pump is of the sin --_---- gle-acting description, 18% inches in diameter, aid having a stroke of 4 inches. The head and fopt valve and the bucket x fitted with metal annular group valves. The pump is driven -by'a sepa. rate crankshaft from the end of the main crank. -.... he boilers; three in number, are arranged two in the after boiler compartment and one in the forward. They are of the Thornycroft Day. ing type modified. Each boiler has 63 square feet of grate surface and 3168 square feet of heating surface. The boilers are constructed for g 'workin g pressure of 210 pound and were tested to 300 pounds per square inch. The vessels have only two funnels. The forward funnel' is used for the boiler in the fore compartment, as well as for one of the boilers in the after boiler space. The after funnel is used for' the remaining boiler and also in connection with the ventilation of the engine toom, On six runs, ote of the vessels equipped with this: machinery, the Handy, averaged 27.006 knots, the speed during one rad averaging 27.48] knots. During the run in which the highest speed was attained the mean indicated horse power was 4,677, vacuum 24% inches, steam pres. sure 195 pounds, air pressure 34inches, and revolutions 888.4 : and 397.5 for port and starboard propellers respectively. bf) Eee Just Double the Suez Traffic, ~~ "y thie truly wonderful to find that the net registered tonnage of ves- sels passing through the Suez canal during the full calendar' year 1895 was barely one-half the tonnage of vessels passing through 'the tee canals at St. Mary's falls during 231 days of navigation on Lake Superior in the same year. This comparison applies as well, of coursé, to the American canal alone at the Sault, as the new Canadian canal was open 'to navigation for only eighty-seven days in 1895, and the commerce pass- sai ul rn ee in ay Ai Rhy sity ENGINES OF 27-KNOT BRITISH TORPEDO BOATS. with a3-inch hole. The crank, crankpin, cheeks, and moving gear have been carefully balanced by means of weights suitably placed. The tun- nel shaft is 6 inches in diameter with 34-inch hole; the propeller shaft is 64 inches in diameter, with 31-inch hole bored throughout. The thrust blocks are of the ring description, made of cast iron, and lined ' with white metal at the bearings. The block is also water-jacketed. Cylinders are each supported on four wrought steel columns, their bottom ends passing through the cast steel bearers, being fastened thereto by nuts on the under side. The barriers are of }4-section. The main bearing bushes are of gun metal, lined with white metal; these bushes are held in position by wrought steel caps, each having two steel studs. The cross-bearers are bolted at each end to the fore-and-aft por- tions of the soleplates, which are made from rolled steel angle-bars, these bars being planed on the face and bottom. The fore-and-aft por- tions of the soleplate or angle-bars are continued forward to receive the air pump, and aft to carry the thrust blocks. By this means the engines are complete and self-contained, so that all strains are well distributed over the shipwork. It will be seen from the design that diagonal bracing is dispensed with, the cylinders for each set of engines being bolted together in a fore-and-aft direction, and diagonal stays are carried from the cylinders to the fore-and-aft bulkheads. The cylinders of the two sets of engines are tied in the athwartship direction together, and also to a fore-and-aft stiffener at the ship's sides. The engines are so placed in the engine-room that there is a passage between, and also between the engine and its corresponding condenser, which is in the win gs andona low level. The condensers, with their tubes and ends, are of brass, the steam being led in on the top and diagonally to give free distribution. Circulating water to the condensers is supplied by two centrifugal pumps having 8-inch discharges, and sufficient for moderate powers. The air ing through it was but about 4% per cent of the entire Lake Superior commerce, with the great bulk of it in American vessels. The Suez canal passed last year 3,434 vessels of. 8,448,383 net registered tons, while the commerce, of the two canals connecting Lake Superior with other parts of the chain of great lakes involved, during 231 days of navigation in 1895, the passage of 17,956 vessels of 16,806,781 net registered tons. These figures are official, as those relating to the Lake Superior canals are furnished by the United States war department, while the Suez sta- tistics have just been received from the London office of that:canal. A more extended comparison of these statistics will be found atthe head of the editorial columns in this issue. A representative of the REVIEW was in theeast recently calling on concerns that supplied material or machinery for lake vessels. One of the most interesting calls was upon the largest concern of its kind in the United States, the B. F. Sturtevant Co. of Boston, Mass. This. company has furnished some fifty or more blowers for draft: apparatus on lake steamers, the North West and North Land being equipped entire with their machines. Some 75,000 blowers of all kinds are turned out of the Jamaica Plains works each year,the foreign trade requiring a large number. The varied uses to which the machines are applied can be imagined from the fact that a blower was shipped recently to a crematory at Washington. The engine department and electrical departments would in themselves make a large separate business. -Their upright engine and direct cot nected dynamos are very compact. Thereis no position in which they do not place their blowers 'on shipboard, using space. which: can not be utilized in any other way. The engineers of the company have collected some valuable data from steamers having different systems of forced draft and this is available for the information of customers.