OCR Text |
Show If HE MODERN STEAMSHIP. fmpotmlble to Guess 'What Speed May N Bo Reached Hereafter. Twenty years ago it was thought by many th ut th6 limit as to size, speed and economy had been reached. At pres ent it soems that the draft of water at tho harbors and tho cost are the limits that will prevent further development on present lines. With different material ma-terial for construction, with liquid f ueL and other improvements or inventions, it is possible that 20 years from now one may look back at tho Lucania with her 21.6 knots as we look back on th Germanio and Britannic of 1874 witi their 16 knots. The steam pressures on ocean steamers steam-ers up to 1&50 did not exceed 20 pounds. With the earlier vessels, with only 5 to 10 pounds of steam, it was possible to stop a leak in a boiler "by pushing a rag in the hole." As late as 1846 a prominent firm of engine builders in England stated that from 10 to 12 pounds was what they used for merchant mer-chant vessels. By 1860 pressure had increased in-creased to from 60 to 90 pounds, and on the introduction of steel for boilers pressures pres-sures went up to about 100 pounds by looo, and zscw bcilorB are being built, for large steamers, to carry 200 pounds. Special types of boilers for torpedo boats and other uses cany much higher pressure. pres-sure. The Ericsson machinery weighs only 66 pounds per horsepower. This last is for torpedo boats and hieh pressures and can not yet bo approached for large vessels. On the trial trip the Minneapolis Minneapo-lis developed 20,813 horsepower, and the total weight of all the machinery, with the water in the boilers, was 1,96 tons, so thae the weight of machinery for each horsepower was about 210 pounds. Had the Minneapolis machinery been of tho same relative weight as that of the Powhatan it would have weighed over 8,400 tors, or 1,000 tons more than the Minneapolis herself weighed on hoi trial trip. Chautauquan. |