American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 67
I LOCAL DYNAMO MACHINE. 49 switch any machine can be readily disconnected and another substituted. Two sp^iremachines are provided and these have switches so connected that the line wire termi-nal and ground terminal may be readily transposed to furnish a desired polarity. Aresistance k^ r^ k^…
Telegraph
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