R.R.S. 'DISCOVERY' 159 



main deck immediately above. A main suction line is led direct from the engine room 

 to the bilge valve boxes. 



The remainder of the compartments between the freshwater tank space and chain 

 lockers are arranged for the stowage of provisions and scientific and other gear. Between 

 the after end of the freshwater tank compartment and the fore end of the boiler space 

 is a coal bunker, the total capacity of this and of the wing bunkers being 208 tons. 



The whole of the spaces below the main deck are subdivided by means of wooden 

 bulkheads, constructed of two thicknesses of tongued and grooved pine, one horizontal 

 and one diagonal, with painted felt between. The two thicknesses are clinched with 

 strong fastenings, providing a watertight construction. In addition to the thwartship 

 bulkheads a similar fore and aft bulkhead extends from the after end of the bunker 

 space to the after end of the chain locker, completely dividing the vessel on the centre 

 line. The forward bulkhead of the boiler room is of steel as in the original arrangement, 

 and in addition a light steel screen is fitted between the engine and boiler rooms. 



Full advantage is taken of the space available in the 'tween decks alongside of and 

 above the boilers for bunker space, the bunkers in this part of the ship being constructed 

 of steel. 



The Propelling Machinery is the same as in the original vessel and it has not been 

 altered in any material way. Steam is supplied by two cylindrical boilers, each 10 ft. 3 in. 

 in diameter and 9 ft. long, each having two furnaces: the combined total grate surface 

 provided is 67 sq. ft. The maximum working pressure is 150 lb. per square inch. 



The engines are of the triple expansion type designed to develop 450 H.P. when 

 working at about 90 revolutions per minute. The diameters of the cylinders are: high 

 pressure 14J in., intermediate pressure 22| in., low pressure 36 in.: length of stroke 

 30 in. The high and intermediate pressure slide valves are of the piston type, the low 

 pressure being a flat valve, all actuated by the usual link motion. The condenser cooling 

 surface is 560 sq. ft. The main air, feed and bilge pumps are worked by levers from 

 the high pressure engine. The shafting is of steel, the crank webs being forged in one 

 with the shaft. The propeller is two-bladed, loh ft. in diameter and with a pitch of 

 12 ft. The boss is of gun-metal, and the blades are of high tension bronze. 



The auxiliar}^ machinery fitted in connection with the main engines comprises a 

 reversing engine, two centrifugal circulating pumps and an auxiliary feed pump. The 

 circulating pumps are each capable of pumping 100 tons of water per hour; they have 

 connections to the bilge and each is arranged with an auxiliary air pump. The outlet of 

 the main condenser circulating water is kept well above the water line, and all pipes are 

 arranged so that they can readily be drained and, as far as practicable, kept above the 

 floor plates. Owing to the special service on which the vessel was to be employed all 

 cylinders, including those of the auxiliary machinery, are made self-draining and each 

 main engine cylinder is water-jacketed. 



On reconditioning the ship certain new auxiliary machinery was installed: a 10 ton 

 evaporator with freshwater distiller working in conjunction with it : an electric generating 



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