Engineering Wonders of the World
Volume I

 142 ENGINEERING WONDERS OF THE WORLD. 75 feet, at Bohio somewhat less, and gradually decrease towards Obispo, CROSS SECTION OF THE GATUN DAM, THE LARGEST EARTH DAM IN THE WORLD. IT WILL HAVE A BASE WIDTH OF NEARLY HALF A MILE. dam, spillway, and locks at Gatun was 4,795,000 cubic yards, considerably more than half the quantity required. The depth of Gatun Lake at the dam and the upper gates of the highest lock will be about thence where the standard depth, 45 feet, has been already obtained. The deeper portion of the lake for sixteen miles—that is to say, between Gatun and San Pablo—will have a width generally of half a mile, and through this there will be a navigable channel nowhere less than 1,000 feet wide at the bottom. Farther S / '' on, however, the width will be reduced gradu- ally to Las Cascadas, where vessels enter the heaviest portion of the great cutting and, for 4’7 miles, the narrowest section of the entire Canal. In this section the bottom width will be 300 feet, and the side walls almost vertical. Ten feet above the normal water-line there will be on each side of the prism a terrace 40 feet wide, that on the east side being in- LIDGERWOOD MECHANICAL UNLOADER. ' An unloader and ten men can move as much material in one day as 400 labourers working with shovels. The unloader, drawn along by a cable, simply ploughs the material off the flat cars.