The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 379
as they have nolateral strength by themselves. At least four stays must beattached to the shortest, and longer poles made up of two orthree tubes should have at least eight—four fixed near the top,and the others at the next joint below. Each of the staysshould be provided with a stay tightener or… … T Fig. 345.—4-Wire Channel-Iron Arm of the roof by means of rafter swivels and pivot hooks, whichare fixed by a bolt passed through the timbers, but they mustbe carefully made off with lead, etc., to prevent leakage of rain;or the stays may be attached to iron-wire bands passed roundheavy chimney…
Telephone
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