Page:Popular Science Monthly Volume 12.djvu/556

This page has been validated.
538
THE POPULAR SCIENCE MONTHLY.

engines having surface-condensers, and with tubular boilers, which are fitted, frequently, with superheaters. One of the best examples of these steamers, the City of Peking, a screw-steamer built by Roach

PSM V12 D556 Modern marine steam engine.jpg
Fig. 60.—The Modern Compound Marine Steam-engine.

for the Pacific Mail Company, is a vessel of 5,000 tons. There are two pairs of compound-engines, having cylinders of 51 and 88 inches diameter, and 412 feet stroke of piston. The crank-shafts are 18 inches in