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250 casing and the rotor. Girders also serve the function of transverse ties in view of the great width of the engine room casing. Starting at the forward end of the ship we have No. 1 boiler room con- taining six boilers, No. 2 boiler room containing six boilers, then No. 3 boiler room containing six boilers, and finally No. 4 boiler room con- taining three boilers. Each of these boiler rooms is a watertight com- partment within a watertight com- partment. The fore-and-aft sides of the boiler rooms are formed by -wa- tertight steel bulkheads, which- are some 18 ft. from the outer skin of the ship, and transverse steel bulkheads fitted with watertight doors, separate adjacent boiler rooms. We thus get watertight compartments on _ both sides of the ship outside the boiler rooms, whose floor levels, usually termed the "inner bottom" are also watertight, extending right across the ship, and situated several feet above the bottom of the ship. In these compartments coal is carried. Access from these to the boiler rooms is gained by watertight doors, fitted in the sides of the boiler rooms, and through these coal is conveyed to the boiler fires. The transverse sides of the boiler rooms are formed of steel bulkheads and are also watertight, with water- _tight doors for communication pur- poses between various boiler rooms and the engine rooms. Prevention Against Flooding In the event of the outer sides be- ing pierced, it is clear that flooding could only take place in the outer compartments or coal bunkers, formed by the skin of the ship, and the longi- tudinal bulkhead forming one side of any boiler room, the water-tight doors in this bulkhead preventing water from flooding into the boiler rooms. Similarly, if the bottom be pierced, water could only flood into the com- partments formed by the bottom of the ship and the inner bottom, or watertight floor of the boiler rooms and the: bunkers. S50 'lone "as" the floor remains intact, water could not flood the boiler rooms above. Fur- ther, the space between the aforesaid inner bottom and the bottom of the ship, is itself divided into watertight compartments by longitudinal steel divisions, so that if the bottom be pierced the space filled with water is thus limited in extent. For such an event as flooding, con- sequent on collision, pumping ar- rangements have been provided for dealing with about 15,000 tons of water per hour. THE MARINE REVIEW Water ballast is carried in the cellu- lar double bottom. formed between inner and outer shells, and this space further provided large stowage capaci- ty for the carriage of fresh and con- densed water. Boilers. We can now take the various units in detail, commencing with the gener- ating of steam in the boilers, There are 21 large double-ended boilers, each with eight furnaces, the .com- bined area of fire: grate being 3,542 sq. ft., while the most efficient parts of the internal surface, in contact with water outside and exposed to flame and hot gases inside, give an aggre- gate of 138,596 square feet, capable of converting 9,600 tons of water into steam per day. : The boilers are constructed. ior a working pressure of 195 lbs. per sq. in., and all work under forced draught. The air pressure is maintained by 28 fans 66 in. diameter, driven by 14 electric motors each 50 horsepower, one motor driving each pair of fans, which are arranged in separate fan rooms immediately above the boilers. The fans are connected to the boiler fronts by trunking, through which is discharged the air drawn in from the boiler rooms. The air is heated by coming in contact with tubes which in turn are heated by the waste gases, and is afterwards blown into the fur- naces and through the burning coal. Thus the air which passes down the huge ventilators on the top deck, first cools the firemen in the boiler rooms, ventilates the. latter, and is finally drawn in by the forced-draft fans and utilized as described above for increas- ing the rate of combustion in the furnaces. Each of the three forward groups of six boilers, with their correspond- ing uptakes and funnels, weighs 1,600 tons. There are four eliptical fun- nels, 24 ft. by 17 ft. and the distance from the top of the funnels to the level of the fire grate in the boiler room is some 160 feet, Great care has been exercised in the design of the boiler room firing plat- form to insure that coal, ashes and dirt do not find their way to the in- numerable pipes carried underneath, and the highest efficiency is thus as- sured, in the case of flooding, for the pumping arrangements, in providing Immunity from choking of pipes. Ash expellers. For disposing of ashes in the boil- er rooms there are seven of the latest ash-expelling devices whose pumps are driven by steam turbines. The ashes are shoveled into a hopper, through gratings which regulate their July, 1914 size, and after being drawn into the expeller, are discharged through the ship's side far below the water line. These machines are fitted in large re- -cesses in each boiler room, which serve for the stowage of ashes after cleaning fires, thus facilitating the work of the stokers by preserving a clear platform at all times. They may also be used as bilge pumps or discharging water overboard: in case of emergency. In addition eight ash hoists are distributed through the boiler rooms. The plant will be called upon to dispose of about 1,200 tons of ashes during the round voyage. On leaving No. 4 boiler room we pass through a watertight door and enter the center engine room, ip which the low pressure ahead and astern turbines are situated; the high and intermediate pressure ahead and astern being located in the part and starboard wing engine rooms respect- tively. In all there are three engine rooms, -one on each side of the center room, to which access is obtained by means of watertight doors in the longitudinal watertight bulkheads. All three com- partments are watertight as in the case of the boiler rooms and bunkers. Turbines The turbines are directly coupled through our lines of shafting to the screws, this arrangement permitting a reasonable sub-division of the im- mense power, and they are arranged as already described in three engine rooms. An important departure from the Cunard company's previous prac- tice has been made in this scheme. The triple compound system has been adopted for the turbines. In giving a greater range of expansion for the steam, this enables high economy to be maintained at normal speed, and by special adaptation of steam dis- tribution, provides for the full use of reserve power necessary during a call for speed. By following the course of the steam this system may be readily appreciated. Thus, enter- ing from the boiler rooms the steam first rotates the high pressure tur- bine in the port engine room; after expending work in passing through the blading, it is exhausted into the intermediate pressure turbine in the starboard engine room, the steam flowing then to a pipe large enough for a man to walk through, leading to both low pressure turbines, mount- ed on the inner shafts and housed in the center engine room. The low pressure turbines then exhaust to the condensers, where the steam comes in contact with some 18,700 tubes, having a cooling surface of 46,000