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140 nor space is of such importance as in high-speed ships. The question is primarily one of economy. Description of Machinery. We are indebted to Mr. Ismay for special permission to inspect the ma- chinery of the Laurentic; the result of our observations must be pro- nounced in terms complimentary to the designers. As to the boilers, there are in both the Megantic and the Laurentic six double-ended steam- generators for a working pressure of 215 lbs. The proportions of the boilers are the same in each ship, the allowance in heating surface being, in accordance with the White Star practice, about 2% sq. ft. per horse- power, while the ratio of heating surface to grate area is 37 or, 38 to 1. With the higher steam efficiency of the combination system of machinery, a reduction on these proportions will- be justified, and it is probable that with experience the design of boilers will be so modified as to compensate for any increase in weight in the engine room. In making the experi- ment with these two Canadian liners the builders and owners have acted with their characteristic prudence, as. the experience gained will enable them to so proportion the machinery in the two immense White Star liners now being built at Belfast as to insure the best results. These vessels are to be of about 45,000 tons gross register, with machinery of nearly 50,000 horsepower to give a speed of 21 knots, so that the application of machinery of the combination type may result in a considerable total saving in consumption, The machinery of the Megantic, the twin screw ship, is of a quadruple- expansion type, the cylinders being 29 in, 41% in, Gl in, and $7 in. in diameter respectively, with a stroke - of 60 in--proportions which will give a very satisfactory range of expansion. In the Laurentic the reciprocating engines are of the triple-expansion type, with four cylinders to insure perfect balancing.. The cylinders in thie -é@ase -/are «30-2 in 46 in, S3:in-' and © $3 in im = digmet- ter respectively, with a stroke of 54 in. 'The general design follows Messrs. Harland and Wolff's prac- tice, with single columns, which give an open engine. In the Megantic, however, the condensers form part of the framing, and the air and cir- culating pumps are placed contiguous to the condenser. In the Laurentic the condensers are of necssity inde- pendent. In this latter ship the en- THE Marine REVIEW gines are at a greater distance apart than in the Megantic, to suit the three-propeller arrangements. The low-pressure turbine of Parsons' latest turbine type is in the center of the ship, and abaft the mas; engines, with one condenser on each side, while the auxiliary machinery is ar- ranged in the wings. We understand that the principal difference in the disposition of the machinery in the two ships is that in the Megantic the electric generators--three sets of Al- len's. machines, of 750 amperes at 100 volts--are placed where the tur- bine is accommodated in the Lauren- tic, while in the latter ship the elec- tric generators take the place of a small coal bunker at the forward end on the port side of the engine room. The center shaft also encroaches on the cargo), space vailable abaft the machinery-room in the Megantic. Confining ourselves now to the re- sult of observations on the Laurentic, we may note that the exhaust pipes from the two low-pressure cylinders, which are at the extreme ends of each engine, are led, with the usual ex- pansion, or bellows, joint, to the forward end of the turbine. On each pipe there is a double-beat valve, op- erated each by a separate high-pres- sure engine secured to the after bulk- head in the engine. room, and con- trolled by levers at the reciprocating engine starting platforms. These en- gines and valves can be worked inde- pendently, but are normally connected, and work simultaneously. The tur- bine will be thrown out of action for all maneuvering: in other words, when the telegraph indicates "stand by." The double-beat valve will then pass steam to the condenser, and the ship will maneuver as a _ twin-screw steamer. The benefit in having in- dependent valves is, that should one of the engines break down, two pro- pellers will be available for driving the ship, one rotated by the recipro- cating engine in service and the oth- er by the turbine. There is thus the advantage that with one engine out of use two-thirds of the total power would be available instead of one- half, as in an ordinary twin-screw ship, so that the reduction in speed would be considerably less. The trial trip results showed the possibility of this maintenance of high power with one engine out of service, as the low-pressure turbine developed 4,600 shaft horsepower out of a total of 12,400 horsepower, the exhaust pressure from the reciprocat- ing engine, and therefore the initial pressure in the turbine, being about June, 1909 18 lbs. absolute. The speed obtained exceded the 16 knots anticipated by the design. The main engines were designed to run under these conditions at about 83 revolutions while the turbine made 220 revolutions. The turbine, as we have already indicated, accorded with Parsons' lat- est practice, and gives 28 shaft horse- power per ton. The thrust-bearing is at the forward end, with the for- ward main bearings betwen this thrust and the rotor, and the after bearing abaft the rotor. The blading is arranged for six. expansions, the lengths being from 6 in. to about 10 in., while the average clearance is about one-tenth of an inch. There is the usual arrangement for ad-. justments, and the bearings are lubri- cated by gravity with two stand-by oil pumps. The shaft-bearings have also water circulating round them. In order to obviate any matter pass- ing over with the steam to the tur- bines, strainers have been fitted in the steam pipe between the recipro- cating engines and turbine; provision is made for lowering these strainers for examination and cleansing. Auxiliaries. As to the' auxiliary machinery aboard the ship, it is of a most com- prehensive type. Weir's independent air-pump and Harland & Wolff's circulating pumps are fitted for -each condenser, and Weir's monotype air pump and Harland and Wolff's cen- 'trifugal pump for the auxiliary con- denser, with the usual hot-well pumps, filters, feed-heaters and feed pumps. The hot water for the baths is got from the condenser, and, like the fresh water, is pumped to supply tanks on the boat deck to gravitate to all parts of the ship. The bilge, sanitary, and other pumps are all of high capacity, and, with the main feed and hot-well pumps, are accom- modated in the engine room. Reserve pumps, however, are placed in a for- ward compartment so as to be avail- able for their duty sfrould the main engine room be flooded. Here are also Hall's CO, refrigerating instal- lations for the holds and for eight independent rooms for storing ship's provisions, the latter being exception- ally' extensive. The refrigerating pipes, ballast pipes, steam leads, and other such communications are in a tunnel over the ballast-tanks, open for winch so that they are always examination, and do not obstruct the alley-ways or decks for passengers. With other features of the ship we shall, we hope, be able to deal later,