Telegraph engineering : a manual for practicing telegraph engineers and engineering students (1922)
Hausmann, Erich, 1886- · New York : D. Van Nostrand Company · leaf 275
ncross-arms: Average maximum downwardload in pounds Longleaf pine (75 per cent heart) 10,180 Longleaf pine (100 per cent heart) 9?780 Longleaf pine (50 per cent heart) 8,980 Shortleaf pine 9,260 Shortleaf pine (creosoted) 73650 Douglas fir 7j590 Wliite cedar 5,200 26o TELEGRAPH ENGINEERING… … Fig. 3. usually provided with double cross-arms, placed on op-posite sides of the poles and bolted together. Lightning Arresters. — To protect pole lines against de-struction by lightning, it is common practice to lead aground wire to the top of at least every tenth pole. Fig. 4shows one…
Telegraph
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