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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
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
