Engineering Wonders of the World
Volume I

264 ENGINEERING WONDERS OF THE WORLD. tower a pleasing taper to the heavy girders which connect them at the top. On these girders are set the four immense saddles— steel castings 19 feet long and 7| feet wide, and 13,0 less than 36 tons in weight—which hold up the cables. Each saddle rests on forty 2J-inch steel rollers 7| feet long, which allow it to move forward as the cables stretch in the heat of summer. While the piers and towers were under construction, work Anchorages. was progressing also on the a n chorages. These are im- mense blocks of concrete and stone, to which the ends of the cables are fastened, and so heavy that the great- est pull on the cables cannot shift them on their founda- tions. In the case of this bridge, the an- chorages are each about 175 feet wide by 155 feet long, and about 120 feet high—solid masses of stonework. The ends of the four cables enter the anchorage and are looped round pins, from which a strong chain of steel bars curves downward to sets of beams firmly bedded in the rear bottom part of the anchorage, so that the entire mass of anchorage would have to be broken apart or pulled off its base before this “ anchor chain ” could shift or pull out. The external appearance of one of these anchor- ages (Fig. 9) gives a good impression of their immense weight. Fig. 9.—ONE OF THE HUGE ANCHORAGES OF THE WILLIAMSBURGH BRIDGE. Each, anchorage is 175 feet wide, 155 feet long, and 120 feet high. Simultaneously with, this work men were busy erecting the steel trusses of the shore spans, and the intermediate towers on which they rest. Wooden staging, technically known as “ falsework,” was erected on the proper line, and on it the pieces composing the trusses were laid and fastened together until the shore span was complete and self-supporting, and allowed the removal of the falsework. In this particular case, the falsework of the shore spans was also used to support the derricks by which the parts of the main towers were raised and set in place. When the towers reached the future road- way level, timber frame- work was built on the shore span trusses for raising the upperportions of the towers and setting the cable saddles. Now fol- lowed the most interest- ing part of the whole work, spinning the cables. The four cables of this bridge are each 18| inches in diameter (one-fifth thicker than those of the Brooklyn Bridge), and contain 7,696 steel wires of -192 inch (about T3^ inch) diameter laid straight side by side. It might bo thought that they could be laid together on the ground and tied in groups or strands to form small ropes, which would then be pulled up to th© tops of the towers and hung in place. Noth- ing of the kind. The wires are passed over