File:Panama Canal Lock Forms.jpeg
The Panama Canal locks under construction in 1910. In the foreground are shown the huge, collapsible steel forms used to mould the culverts into the side walls; behind can be seen the towering wall forms, mounted on rails to allow the locks to be constructed in sections. Each of these was 78 feet high and 36 feet wide.
From The Panama Canal, An address to the National Geographic Society, by Colonel Goethals, February 10, 1911.
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