Chicago : Engineering and Contracting Pub. Co. · leaf 193
an article published in the Min- 4 SandTherefore Bullel Proof three men each, or 30 men. One occasion ittook three men an entire shift to drill one 10-ft. hole. It was the custom for two men tostrike with hammers, and one man to twistthe steel, which was single bitted. When 8-ft.depth was attained,… … Stove with Coi/sfor Hot Water The gopher holes were put in about 20 ft.apart, and would lift about 15 ft. of rock.Three or four were fired at once, and whenproperly tamped, they broke the ground nicely,without throwing the fragments. On oneoccasion a misfired hole went off just as theminer had…
Buildings
Internet Archive · University of Illinois Urbana-Champaign · Public Domain Mark 1.0. Free to use for anything.
