Engineering Wonders of the World
Volume I

mes The Steel=frame Building, as we know it to=day, is a masterpiece of engineering skill. it provides accommodation for the population of a fair - sized town, and represents worthily the advances made in metallurgical and structural know- BOLTING A COLUMN. {Photo, Illustrations Bureau.) ledge during the past fifty years. BY W. NOBLE TWELVETREES, M.Inst.Meeh.E. Origin of the Steel-frame Building-. THE genesis of the steel-frame building, known colloquially as the “ sky- scraper,” is due primarily to the high, cost of sites in the great cities of the United States—notably New York, Chicago, and San Francisco—and the importance of having business offices in close proximity to the centre of commercial life. Although land is of great value in the central parts of London, Paris, and other European cities, it is always possible to extend the mer- cantile quarter into outer regions—a develop- ment which is constantly in operation. In places like Chicago and New York, however, there are obstacles to lateral expansion, and the inhabitants of those cities have adopted the policy of spreading themselves out verti- cally rather than laterally, by the aid of lofty steel-frame buildings. The business districts of New York cover the southern end of Manhattan Island, where land fetches enormous prices. A corner plot at the junction of Broadway and Wall Street sold for £120 a square foot—the highest price ever paid for a building site. The triangular site on which rises the famous Flat-Iron Build- ing cost half a million pounds sterling. No wonder, then, that in New York engineers and architects have turned their attention very seriously to the problem of securing more ample office accommodation by increasing the height of buildings. With brick and stone the limit had been reached at from twelve to fourteen stories, as the necessary thickness of the walls at the foundations diminished the floor space to a serious extent. Architects therefore took advantage of the fact that mild steel is at least two hundred times stronger than brickwork in compression, and infinitely stronger in tension, VOL. II.