Smithsonian Report. 1935. — Nelson. W. R. 



Plate 4 







1. Headquarters of Boulder Canyon Project, seen From the Air. 

 Boulder City. Nev. 



View looks northwest. December 1.3, 1934. 



2. Truck Mounted Drill Rig Used by Contractors in upper Portion of 



Diversion Tunnels. 



Rig is seen in tlie position in which it approaches heading. April 20, 1932. 



