Handbook for the use of electricians in the operation and care of electrical machinery and apparatus of the U.S. seacoast defenses (1902)
United States. War Dept, Anderson, George Lucius, 1849-1934 · Washington, Govt. Print. Off. · leaf 203
162 HANDBOOK FOR ELECTRICIANS. … 201. Cross=section of lron=Pipe Conduit. clay conduit set in concrete. Both of these ducts connect manholes about 350 feet apart and will last indefinitely. (2) Wrought-iron pipe duct (figs. 201-3), in 20-foot lengths, of 3 to 4 inches diameter, i inch thick, dipped in tar to prevent rust, are…
Electric machinery · Searchlights · Coast defenses
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
