The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 419
e standard practice inAmerica is to make the manholes of concrete moulded in posi-tion by the help of temporary wooden templates or moulds.The form generally given to them is egg-shaped in plan, withflattened ends where the ducts terminate, this shape beingadopted for greater strength to resist… … 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
Telephone
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