. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 134 LECTURE shut one door behind him before opening the other, which leads into the interior of the cyhnder. All being made tight, air is pnrnped into the cylinder by an engine, and the water forced downwards in the pile until it is all driven out at the bottom; workmen then enter through the air-lock, which only permits a small portion of the enclosed compressed air to escape as the doors are opened, and descending to the bottom excavate t
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. 134 LECTURE shut one door behind him before opening the other, which leads into the interior of the cyhnder. All being made tight, air is pnrnped into the cylinder by an engine, and the water forced downwards in the pile until it is all driven out at the bottom; workmen then enter through the air-lock, which only permits a small portion of the enclosed compressed air to escape as the doors are opened, and descending to the bottom excavate the soil under the edge of the pile and in the centre allowing it to sink down gradually by its own weight. It is directed in a vertical position by guides above. As the pile sinks, new cylinders are added to the top, when necessary, and after the whole is down to a firm foundation the interior is filled up with rough stone or concrete, the air-lock removed, a permanent cap substituted, and the superstructure raised upon it. In loose, sandy bottoms these piles have been sunk by permitting the air to rush out under the edge of the pile and by carrying out with it the sand so as to make an annular channel into which the pile settles by its own weight. Man}' bridges in England and on the continent, and some in this country, have been built in this way with great success. One of the most interesting examples is that of the new bridge over the Rhine at Kehl, near Strasburg, where caisson piles were sunk to a depth of sixty feet below the surface of the Avater. ^ Frequently the bed of the river, between masonry piers and for. a short distance above and below them, is paved, planked, or covered with loose stone, to prevent the current from undermining the structure. The foundations having been completed, and the piers having been built up to a certain level, the bottom of the beam of a truss bridge and the spring of the arch of a stone bridge, preparations must be made for adding the s
Size: 2376px × 1052px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorsmithsonianinstitutio, bookcentury1800, bookdecade1840
