Electricity for everybody; its nature and uses explained (1895)
Atkinson, Philip · New York, The Century Co. · leaf 211
Fig. 84. The Key.—The transmitting instrument is called akey, and is constructed as shown in Fig. 84, with a THE TELEGRAPH AND TELEPHONE. 195 hinged lever which can be depressed by an insulatingknob in opposition to a supporting spring, so as to bringinto contact two points, shown under the lever… … Fig. 85. with the upper point, by the right-hand attachment bolt,and the other terminal connected with the lower point bythe left-hand attachment bolt, which is insulated fromthe other parts. The movements of the lever can beadjusted by set-screws to any required range, as shown. When the key is…
Electricity
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