American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 549
g number.One form of a street fire alarm box with doors open is shown in Fig. 327. In general these signal boxes are now supplied with an outer and inner door, as•indicated in that figure, to protect the electrical apparatus from the elements. The signaling mechanism of the box shown in Fig. 327 is… … SIMPLE FIRE ALARM CIRCUIT. hook H, wliicli extends to the front of the inner door, is placed directly over the endof h, in such a manner that when the hook is pulled down from the outside of theinner box, the weight is raised. The weight in falling is caused to operate the break-wheel, as a recoil…
Telegraph
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