The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 480
L MEASUREMENTS 45* up that a current passing through all, tends to turn thecombination in the same direction. The terminals of theinstrument are fixed on an ebonite base, fitted with spiritlevels and levelling screws, and the coils, etc., are covered witha case having glass sides. On top of the… … Fig. 426.—Lamp and Scale for Kelvin Galvanometer lamp, supported on a stand furnished with a graduated screen.A hole in the centre of the stand is furnished with a brass tube,in which a lens is fitted. Through the latter a beam of lightis made to fall on the mirror in the galvanometer, from whichit…
Telephone
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