American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 590
k, which, by transmittingthe signal, announces to headquarters his presence at a certain box. An answer THE CHICAGO POLICE PATROL TELEGRAPH SYSTEM. 479 back signal on the bell, within the box, informs him that his report has been receivedand he may proceed on his beat. If the policeman should be… … set a device which will automatically transmit this pre-arranged signal immediatelyafter the completion of the officers signal, thereby holding him. One means bywhich this is accomplished is shown in connection with the .viunicipal patrol system.The arrangement of the telephone apparatus is shown…
Telegraph
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