Engineering Wonders of the World
Volume I

THE BRIDGES OF protection—a novelty in cable wire—and will be covered with a spiral wrapping of Norway iron wire. The graceful steel towers are an- other original feature. Corresponding to their four-post construc- tion, the bridge has four stiffening trusses. The double-deck floor accommodates four elevated railway tracks, four trolley tracks, a wide carriage-way, and two footwalks. How the piers, towers, and anchorages were built may be understood from the previous review of the Williamsburgh Bridge work, so we will not stop to describe the process again, as our attention is engaged more specially by the highly important operations of cable- making. This picturesque work was done with phe- nomenal rapidity. The 37,888 wires were put Fig. 13.—ANCHORAGE OF MANHATTAN BRIDGE, NEARLY COMPLETED. Fig. 14.—RUNNING OUT ON THE FOOTBRIDGE ROPES TO LAY THE WOODEN FOOTPATH FLOOR, MAN- HATTAN BRIDGE. NEW YORK CITY. ' ' 267 Fig. 15.—ONE OF THE MANHATTAN BRIDGE TOWERS DURING CONSTRUCTION. Each tower contains 6,000 tons of steel. in place in just four months. Though begun only in August 1908, the cables were finished by December of the same year. When the towers were up, footbridges had to be erected, for the use of the workmen who place and adjust the wires of the main cables. To this end sixteen 1-inch wire ropes were drawn Footbridges over one tower, thence through lor the the water to the opposite side, Cnblc Work, and up over the other tower. Hoisting engines pulled these ropes up out of the water and raised them to the desired height—that is, a few feet below the line of the cables. Then the ropes were tied together in groups of four, so that, when their ends were secured to the anchorages, there were four substantial foot- bridge supports. Men now set to work laying a wooden floor over the ropes. Sliding down