The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 482
ts freedom from the effectsof external vibration and magnetic influences. It is not,however, so sensitive, and has not the all-round usefulnessof the Kelvin instrument. Fig. 428 shows its construction.Between the poles of a strong compound horseshoe magnetis fixed a soft-iron cylinder, which serves… … Fig. 428.—DArsonval Galvanometer wires also serving as connections to the coil. A spring atthe bottom and torsion screw at top serve to adjust. When a current passes through the coil the latter is de-flected to one side or the other, the coil tending to set itselfat right angles to the line joining…
Telephone
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