The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 87
d an ebonite or black fibre sleeve. The double-pole magnet is fixed at the terminal end by a screw passingalso through the ebonite terminal block,as shown. The faces of the pole-piecesand the rim of the outer case are groundflat, so as to be all in the same plane, anda brass ring about 16 mils in… … Fig. 46.—Scale \ clamping ring,which clamps thediaphragm in posi-tion. The case
Telephone
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