Engineering Wonders of the World
Volume I

98 ENGINEERING WONDERS OF THE WORLD. THE ARCH RIB COMPLETED. {Photo, Cleveland Bridge Company.) Observe the great safety net stretched under the work. eventually it was removed, as the men com- plained that, instead of making them feel more secure, the sight of it caused The nervousness. It may be re- Safety Net markec[ }iere that the experi- and Nervousness. enced bridge-builder never gets dizzy, and foolhardiness is a greater danger than nervousness. Without hesitation he will walk across a beam only a few inches wide, even when a high wind blows gustily and his foothold is made pre- carious by ice and snow. The new hand soon gets accustomed to positions the perilousness of which really depends on his nerve. Thus when a “ skyscraper ” is in its earlier stages he may feel great reluctance to cross a broad plank, but by the time he has helped to build it to a height of 500 feet above the street he experiences no qualms whatever. Progress became more rapid as the canti- levers advanced, and the amount of steelwork in each panel—that is, section of bridge be- tween two upright posts—di- minished. The last eight panels Cantilevers at the centre of the arch (out joined. of twenty-six in all) were put together in twenty-six days, and on April 1, 1905—less than six months from the start— the great 3-foot square booms of the arc were joined. The rapidity of the work bears wit- ness to the efficiency of the workmen and the designer, and to the precision with which the parts of the steelwork had been made. In order to give the top chord its proper share of the final strain, a slight gap was left in it until the arch was complete. Hydraulic jacks forced the ends apart to create the required strain, while packing-pieces were in-