The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 200
cord boards is to join thedrop coils to the two outer springs of the jack, and use a singledouble-strand cord, with a 2-point plug joined to each end forconnection. When lines are connected, both drops are then SMALL SWITCH-BOARDS 175 left in shunt to the lines, and both fall when the clearingring… … r jpa/- y.-« □ s> The. earth,on thecentreopservice instrument bellcous when the hook isdown, 15 only necessarywith automatic clearing Fig 202 junction lines are furnished with special apparatus, and theworking is modified. Two jacks (Fig. 202) are fitted for theexchange line, the upper one…
Telephone
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