The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 130
Fig. 107.—Scale i Fig. 108.—Scale £ globule of easily fusible metal in the centre, as shownat K in Fig. 108 (which is a sectional view of one sideof the terminal block), which, with prolonged sparking, dueto contact with high-tension-current systems or lightning,melts, and joins the two blocks… … M F Fig. 109.—Scale \ Fig. 109, surrounded by asbestos, and enclosed in a fibre tube, A.It melts instantly with a current of 2J to 3 amperes. The heat coil r of Fig. 109 is of 43 ohms resistance, and iswound on a metal bobbin, M, which is joined by means offusible solder, l, to a metal stud, q,…
Telephone
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