TWIN SCREW ENGINES. 75

being common to the respective cylinders, andconnected to the condensing chambers. Thesupply steam pipes are secured to the slidevalve casings, over the back ends of thecylinders. The main supply pipe is connectedat the forward end of the arrangement.

The slide valves are the equilibrium doubleported type, similar to those already described.The link motion also presents no novelty forfurther comment. The hand wheels and shaftsare supported in vertical columns—seen in planand elevation. The feed and bilge pumps aresecured at the sides of the frames, motionbeing derived from the piston rods, or directfrom the steam pistons, if preferred. The *doors for access to the valves of both air, feed,and bilge pumps are respectively arranged; alsothe supplementary valves, detailed allusion towhich, for the present purpose, is not re-

quisite. It may be added, that in the eventof the space between the back ends of thecylinders not being sufficient for the con-denser, &c., as at present arranged, thearrangement adopted by the Messrs. Maudslaywill be the better.

Another mode of arranging the cylindersand condensers—when oppositely situated—isto secure the condensers between the crankshafts, and the cylinders beyond the same, ateach side of the hull. Some authorities preferthe screws as close together as their diameterswill permit, for protection, or prevention fromfouling. Other advocates recognize the steer-ing acquisition only, and thus increase thespace between the screw shafts proportionately.In conclusion, therefore, it can be stated thatthe beam of the vessel regulates the type ofengine for twin screw propulsion.

2 L