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der and one set of steering gear are below the water line, and in the way of the engine and boiler rooms there are side bunkers, which, filled with coal or water, will be equivalent to an ar- mor belt round the vulnerable portion of the ship. The following interesting table shows at a glance the progress made by the Cunard company in connection with the speed dimensions and accommodation of their various vessels, as time has proceeded, the enormous advance of the Lusitania on the Campania being particularly noticeable. "TAE Marine. REVIEW be so necessary to build such very large ships. This, of course, would some- what reduce the power for a given speed. The case of the torpedo boat destroyer is quoted; but destroyers have limited fuel capacity; the Atlantic liner has to carry coal to maintain her maximum speed for a voyage of 3,000 miles across the Atlantic. This itself is a very heavy load, and there is in- volved a great increase in size and in weight of constructional material, which again necessitates great power. The importance of making a ship of very fine lines, and consequently of secur- Another table. of exceedingly great ing the least possible coefficient' of S Se) ; z a eS 4 ay Oo co re oO : 8 RG. oO ; a oe . g é g ° ae as eg, 3 ee a a oe a. &§ = e i § a 3 S 3 . A O Pp Oo 4 Coal necessary to steam to New York (tons)........ 570 1,400 836: 1,900 2,900 '5,000 Gargo cattied Cons) ii a ccecaesca ches or ee 224 7904-700; 1,000 * 21,620 41.500 Passengers wee e WinieiWeg ergietaruya Ti anewcs GA plea ciao uier Sole sq 115 250 620°) 1255. 251,700" 625350 Indicated "horsepower 46.4. oe eG a 710 3,600 5,000 14,500 30,000 68,000 Steam PIESSUTE CUD ee ee Ce ae aie ees 9 33 75 110 165 200 Coal per indicated horsepower per hour Cb). tee Dt 3.8 1.9 1.9 129 1.45 Speed CENOER) iss ak ee i os ce oo, BS 7 Ae eae 19 22.) 25 interest is"one which shows in juxta- fineness, calls for length as well as position the dimensions and other par- ticulars concerning the Lusitania, the - Campania, and the Kaiser Wilhelm II, the last mentioned boat having tem- porarily wrested the supremacy of the Atlantic from the Campania only to be herself outmatched by the great Cun- ard flyers: ; NAME OF SHIP, 1 Kaiser . Lusitania. Campania. Wilhelm II.: Length : Overall 24: 7-785' ft, 622 ft. 706 ft. 6 in. Breadth molded .. 88 ft. 65 ft. 3 in. 72% ft. Depth mold- Obie. as « 60 ft. 6 in, 41-ft. Gin; 52% ft. Gross ton- : nage ....32,500 tons 12,500 tons 20,000 tons Draught 3... 33-ft. 25: ft. 29 ft. Displace- ment ....38,000 tons 18,000 tons 26,000 tons No. of pas- sengers-- first %... 550 600 715 No. of pas- sengers-- * second .. 500 400 343 No. of pas- sengers-- third 2 23,300 ' 700 770 Type of en- i gine .... Turbine Recipro- Recipro- cating. cating. Total i.h.p. 68,000 * 30,000 38,000 to * - * 40,000° Speed 25 knots 22knots 23% knots Engineering in the course of along description of the Cunard liner Lusi- tania, says that the ship is the largest yet constructed, alike - in draught and displacement; but this is not due so much to requirements for high speed as to the need for providing extensive accommodation to ensure satisfactory revenue, in order, as far as | 'possible, to meet the expense of the great speed. The proposal has often been made that first-class passengers should only be carried on high-speed Atlantic liners, as it would not then length, great beam; and thus, notwithstanding the continuous aim on all hands to economize the size of the ship, each increment in speed has involved a great advance in size. The 20-knot. Atlantic liner of twenty years ago had a displacement of 10,500 tons; the 22- knot ship of ten years ago was 18,000 tons; the 23-knot ship of five years ago, 23,000 tons; and now to reach 25 knots it has been found necessary to raise the displacement weight to 38,-. ooo tons. The dominant factor in this great increase of displacement is the great addition to engine power for a> comparatively slight increase in speed. Thus, twenty years ago the ratio of power to displacement for a 20-knot speed was 1.35 to 1; for 22 knots ten years ago; 1.66 to 1; and today for 25 knots, it is 1.8.to 1.. Thus, for an ad- vance in speed in twenty years equal to 25 per cent, the power has increased from 14,000 to 68,000, or nearly five- fold. It is true that with increased economy the coal consumption per unit of power is considerably less--25 per cent--but notwithstanding the less time taken on the voyage, owing to in- creased speed from Liverpool to New York, the total tonnage of coal has gone up from 1,900 to 5,000 tons. The table appended is instructive from this point of view. It shows the reduction in consumption pef unit of power per hour, due largely to the increase in steam pressure; but it indicates also a very steady advance in the power nec- essary to obtain the increase in 23 speed. Since the first Cunarder was built, sixty-five years ago, the speed has been multiplied only three-fold, but the power has had to be increased nearly a hundred-fold. Owing, how- ever, to the higher economy, and the shorter time taken on the voyage-- about four and a half days, as com- pared with fifteen days--the coal con- sumption. for the voyage is only ten times greatér. LUSITANIA'S TURBINES. In the course of an exceedingly in- teresting description of the engines of the Lusitania, the engineering corres- pondent of the Glasgow Herald gives the following particulars: The machinery, however, is after all the most important feature in the ves-_ sel. As already indicated, there are four shafts, each driving an independ- ent propeller. .On the two-wing shafts there are the high-pressure turbines taking steam direct from the boilers. After the steam has' passed through these, driving the long series of rings of blades, connected to the shaft, it passes to the low-pressure turbines. mounted on the inner shafts, does sim- ilar work in them, and _ ultimately passes into the condensers. On the inner shafts there are large turbines for driving the ship astern. Thus there are six turbines--four for ahead and two for astern motion. In the con- struction of the turbines the first oper- ation consisted in forging the shafts, © and the rotor drums to be mounted on the shafts. These forgings, of great weight and strength, were made at the Atlas works of the company at Shef- field. Simultaneously there were cast the casings which enclose the rotors, with their thousands of blades, for utilizing the velocity of the steam to give the shaft its rotary motion. These casings are also massive pieces of work, a fact which will be appreciated -- when it is stated that the rotor casing and blades of the low-pressure tur- bines of the ship weigh about 450 tons. While the rotor is in one piece, the casing requires to be in halves, the one for the lower part of the circumference and the other for the upper. Both are ultimately bolted together to form a complete circle. Around the rotor grooves were turned into which the actuating blades were secured; while on the inner surface of the casing there were similar grooves formed for the fixed blades to guide the steam against the moving blades on the rotor. The work of turning the rotors and casing required to be most precise, be- cause there will only be something like one-twentieth part of an inch between the tips of the rotating blades and the