Fig. 163.—An eccentric.
10. When 3 cu. ft. of water are used for a hot bath and the water has been heated from 50°F. to 112°F., how many B.T.U.'s have been absorbed by the water?
11. If the average temperature of water at the surface of Lake Michigan is 50°F., how many B.T.U.'s would be given off by each cubic foot of water at the surface, if the temperature of the water should drop 5°F.?
12. In a cold storage plant carbon dioxide gas is used. The pipe leading from the compression pump to the expansion valve passes through a condensing tank of cold water. Why?
13. When the gas is compressed in a cold storage plant, what becomes of the energy used by the compression pump?
14. An eccentric (Fig. 163), is a round disc mounted a little to one side of its center, A, on the engine shaft B. A band, C, on the circumference of the disc is connected by a rod, D, with the slide valve in the steam chest. How is the rotary motion of the shaft changed into a backward and forward motion of the slide valve?
(4) Heat Engines
196. The Gas Engine.—One of the heat engines in common use to-day is the gasoline engine. It is used to propel automobiles and motor boats, to drive machinery, etc. The construction and action of a gasoline engine may be understood by studying a working model, or by proper diagrams.
Fig. 164.—Cut away view of a modern automobile engine, with parts requiring attention most frequently, indicated. (Courtesy of the "Automobile Journal")