American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 93
creasesdirectly with its length, the longer the wire, the weaker will be the current. The magnetism developed in a given electro-magnet, such as a relay, or sounder, in-creases with the strength of current in the coils, and also with the number of convolu-tions of wire in the coils; the resulting… … THE BUNNELL SOUNDER An instrument to produce sounds loud enough to be easily heard by the operator,requires that the apparatus should possess considerable mass, and iis its moving partsrequire to be actuated quickly and without lag, the use of a strong retractile spring isentailed. This…
Telegraph
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