Rock Drill Small 251×320 Medium 503×640 Large 804×1024 Download Tiff Original 1885×2400 | (1.2 MB) Description A high powered pneumatic or electrically driven device for boring holes into rock. Keywords device, drill, Hammer, hammerdrill, percussion, pneumatics, tool Galleries Miscellaneous Tools Source: Government Printing Office Official Gazette (Washingon, DC: Government Printing Office, 1912) Courtesy the private collection of Roy Winkelman
