"# 745 Drilling Jumbo in operation in the face of one
of the Diversion Tunnels. From 20 to 25 drills can be operated at once and one-half of the face drilled in one operation. December 8th, 1931.
# 671 View of the drilling Jumbo taken outside the
Diversion Tunnels. It is of welded steel con¬struction, mounted on a truck chassis. December 13th, 1931.
# 747 Another view of a drilling Jumbo, backed up to the tunnel--face, showing the method of con¬struction and mounting. December 8th, 1931.
# 748 100-ton Marion Electric Shovel excavating blasted rock from one of the Diversion Tunnels. A three-and a half cubic yard dipper is used on these shovels. December 8th, 1931."