The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 419
Fig. 389.—Section of Double Manhole (Scale fa) building which has found a good deal of favour in America isto use large concrete blocks, moulded in five different shapes … Fig. 390.—Sectional Plan of Double Manhole (Scale fa) suitable for the formation of manholes of a similar egg-shape.This is found to be a cheaper and more rapid method of buildingthan that of direct moulding on the spot. UNDERGROUND WORK 391 For access to manholes iron steps are built into the…
Telephone
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