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Show fHE MODERN STEAMSHIP. ImpoftIbl to Gaesg What Speed Hay Nut Be Reached Hereafter. Twenty years ago it was thought by maDy fast the limit as to size, speed and economy had been reached. At present pres-ent it seems that the draft of water at the harhsrs and the cost are the limits that will crevent fnrther rlovftlnnmfmt on present lines. With different material ma-terial for construction, with liquid fuel, and other improvements or inventions, it is possible that 20 years from now one may look back at the Lucania with her 21. C knots as we look back on the Germanio and Britannic of IS 74 with their 16 knots. The steam pressures on ocean Eteam-ers Eteam-ers up to 1850 did not exceed 20 pounds. With the earlier vessels, with only -8 to 10 pounds of steam, it wa3 nossible to stop a leak in a boiler "by pushing a rag in the hole." As late a3 1846 a prominent firm of engine builders ir England stated that from 10 to 12 pounds was what they used for merchant mer-chant vessels. By 1880 pressure had increased in-creased to from 60 to 90 pounds, and on the introduction of steel for boilers pre-sures pre-sures went up to about 100 pounds by 1885, and now boilers are being built, for large steamers, to carry 200 pounds. Special types of boilers for torpedo boats and. other uses carry much higher pressure. pres-sure. The Ericsson machinery weighs only 66 pounds per horsepower. This last is for torpedo boats and nigh pressures and can not yet bo approached for large vessels. On the trial trip the Minneapolis Minneapo-lis developed 20,812 horsepower, and the total weight of all the machinery, with the water in the boilers, was 1,961 tons. 60 thac the weight of machinery for each horsepower was about 210 pounds. Had the Minneapolis machinery been of the same relative weight as that of the Powhatan it would have weighed over 8,400 tons, or 1,000 tons more than the Minneapolis herself weighed on her trial trip. Chautauquan. |