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344 THE MARINE REVIEW FIG, 2—STERN VIEW OF SOUTHWARK through a valve, undergoes a drop in temperature to considerably below the freezing point and it is contended by some authorities that the entrance of this cold air may be the cause of cracked cylinders, cylinder heads and pistons. Eliminates Drop in Temperature In the Southwark-Harris engine, the necessity of admitting high pressure air into the working cylinders, with the corresponding lowering in temperature, ‘just at the time when it is necessary to build up a temperature, is effectually eliminated by the use of the step pistons. Incidentally, each scavenging piston has a greater area than each of the main pistons, thus permitting the engine to be started under load, with air at 175 pounds pressure instead of at the usual pressure of 800 to 1,000 pounds. Another feature made possible by the ‘use of the step pistons is that while starting on air, the atomizer valves do not operate until the operator engages them and, consequently, the engine is provided with no by-pass valves. Each cylinder is provided with only one cam which is employed for operating the atomizer. Scavenging air is admitted to the working cylinder through ports in its circumference and the exhaust gases pass through ports located opposite the scavenging ports; these ports are so placed that the piston opens and shuts them at the correct time during its stroke. Acts as Crosshead Each step piston, being subject to very little expansion and contraction, may fit rather snugly in its cylinder and thus acts as a guide and cross-head for the working piston, taking the side thrust of the connecting rod and keeping the wrist pin away from the hot working piston. An additional advantage af- forded by this engine is that the air drawn in by the scavenging pumps helps to cool the working pistons, the air itself thus being heated slightly at the same time. As a result, this scav- enging air never enters the working cylinders cold. The reversing of the engine is ac- complished by moving one rod on each cylinder, which can be done by hand without the use of compressed air, the same wheel or lever which admits the starting air and the fuel oil, controlling these rods- Speed Control Simple The governor is. of the centrifugal type, acting directly on the fuel pumps by varying the strokes of all the pumps at once. The speed of the engine may September, 1915 be varied instantaneously, the governor all the time maintaining complete con- trol. The governor may be set to any speed before starting the engine, and, when started, the engine will come to this pre-determined speed and remain there. This feature is of especial ad- vantage in the case of a heavy head sea with the engine racing. Has Wide Range of Usefulness The Southwark-Harris engine was in- vented by Leonard B. Harris and is being manufactured by the Southwark Foundry & Machine Co., Philadelphia, which has been granted the United States license by the Harris Patents Co. The patent in this country is owned by the Harris company, Phila- delphia, and patents already have been obtained in three countries and applica- tion has been made in eight more. The engine, it is said, may be oper- ated on any grade of fuel or crude oil having a gravity of 18 Baume or more, without preheating. Tt. can be made in any size unit desired, being adapted for use on tugs, po- lice, pilot, and fire boats, lightships, ice patrols, submarines and passenger and auxiliary vessels. It is claimed that a tug equipped with such an engine could be provided with capacity for holding oil sufficient to last for a year’s operation. Economical operation would result, it is.said, from the fact that an engine of this type could be gotten under full speed without any delay. The engine is also made in small sizes for driving electric generator sets on large passenger vessels, battleships, etc. and may be used for supplying power for moving railroad care, for stationary power plants and for general power and lighting purposes. FIG. 3—SOUTHWARK-HARRIS DIESEL TYPE ENGINE, WITH SIDE REMOVED TO SHOW CRANK CASE INTERIOR PLATE