Public domain
Butte, Montana. Anaconda Copper Mining Company. Bits for the pneumatic drilling machines are classifed as to length of shaft in this automatic machine; a segregation of bits to one-thirty-secondth of an inch is maintained
From the collection of Library of Congress. Free to download, adapt and use — no permission needed.
Credit lineButte, Montana. Anaconda Copper Mining Company. Bits for the pneumatic drilling machines are classifed as to length of shaft in this automatic machine; a segregation of bits to one-thirty-secondth of . 1942-01-01. Lee, Russell. Farm Security Administration/Office of War Information Collection, Library of Congress. Public domain.