53 



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 







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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 diam- 

 eter, and 4|- feet stroke of piston. The crank-shafts are 18 inches in 



