Scientific American 69 JANUARY 20, 1906. shown the method by which he proposes to carry on excavation after the opening of the canal, without in- He believes terference with navigation. His first step would be ing through the full length of the summit level. In this he would place dredges and… … the lock gates would be slope of the _ sea-level This device is used for under-water excavation. The heavy chisel, weighing 15 tons, is shod with a hardened steel point. It is mounted on a twin built of the same double prism, as shown by the ecow and hoisted, and let fall, like a pile-driver…
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