Engineering Wonders of the World
Volume I

146 ENGINEERING WONDERS OF THE WORLD. AT WORK IN THE CULEBRA CUT. moving the spoil rapidly to distant “ dumps,” a very high standard of organization is de- manded. Otherwise the efforts of the largest labour force which might be placed on the ground, assisted by the most powerful of ma- chinery, might readily be squandered. For example, it may be noted that, whereas in 1906 the average' daily output per steam-shovel was 535 cubic yards, the same machine now disposes of three to four times that quantity. Much of the French plant was kept at work in the Culebra cutting during the early period of the American occupation, and its trial proved what were the best Machincry types of machinery suitable for more extensive operations. All the methods of dry excavation previ- ously employed, whether side excavation with buckets, “ hill-diggers,” swinging derricks, or cableways, were costly and. wasteful. Ma- chinery capable of handling material on a much larger scale was needed. The engineers imported American steam-shovels of great capacity, and had to scrap, as a consequence, the French and Belgian locomotives and dump cars as too small and fragile for the work. Of the hundred and one Bucyrus or Marion steam-shovels now in the Isthmus, between fifty and sixty are constantly digging on the Steam- shovels. various levels of the great cutting. They are usually 70 or 95 ton machines, with dippers that scoop up from 2 J to 5 cubic yards of material at a single stroke. The scoop is armed with four great teeth of manganese steel, has a flap bottom, and is mounted at the end of a steel neck or handle. When working in a cut- ting, the sides of which are earth or soft rock, the scoop is thrust against the bank and raised slowly, scraping A MECHANICAL SPREADER AT WORK. This wonderful machine distributes material dumped from spoil cars in one-fifteenth of the time which would be required were hand labour only employed. off a portion of the surface. In excavating harder rock, however, blasting usually pre- cedes the operations of the steam-shovel. I Thø scoop is then forced into a mass of débris,, of which the largest machines can lift 10 tons at a single stroke. The dipper full, the neck is raised and swung round until the dipper is immediately over a dump car. The scoop is emptied either by opening the flap bottom, or when it contains a specially heavy load or very large pieces of rock, by being thrust into the car itself. The various motions, occupying very few minutes, give a fascinat- ing display of prodigious strength combined with almost human intelligence.