Captions: On the left, the gate structure to #4 diversion tunnel, 165 ft high. On the right side the upper portal to #3. Note: bulkhead in foreground, will be blown out after the completion of coffer dam, allowing water to pass thru; Coffer dam - Boulder Dam '32; Looking down a completed tunnel. Just before the water was diverted. Sunday Nov. 13, 1932, Hoover Dam.
Captions: View showing a section of sheet piling in the upper cofferdam; Diversion tunnel #4 - a hole 50 ft. in dia. surrounded by 3 ft. of concrete - Hoover Dam, Oakes 229; Reclamation truck.
Captions: Trucking mammoth concrete buckets in the 50 ft. dia. tunnels at Hoover Dam, Oakes 228; The Grand Canyon bridge, Arizona [postcard]; Catwalk across Colorado [River]; Colorado [River] from lookout point;