This is a rarely seen back of the Hoover Dam before it filled with water 1936. Hoover Dam is expected to be one of the last remaining visible structures from our species and it contains a star map that if no other means were available, could be used to determine the exact date on which Hoover Dam was completed.
Francis Crowe, the chief engineer of the Hoover Dam, was awarded two patents for design of special steel buckets used to deliver the concrete. The buckets were 7 feet high (2.1 m) and almost 7 feet in diameter. These buckets, which weighed 20 short tons (18 t) when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars. The buckets were then suspended from aerial cableways, which were used to deliver the bucket to a specific column.
Publication number: US1234734 A
Patent Title: Dumping device for excavating-buckets
Publication date: Jul 31, 1917
Filing date: Dec 7, 1915
Priority date: Dec 7, 1915
Inventors: Francis Trenholm Crowe
Original Assignee: Francis Trenholm Crowe
Publication number: US1560895 A
Patent Title: Excavating bucket
Publication date: Nov 10, 1925
Filing date: Mar 9, 1925
Priority date: Mar 9, 1925
Inventors: Trenholm Crowe Francis
Original Assignee: Trenholm Crowe Francis