American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 453
DISTRICT TELEGRAPH SWITCH* 0/ 8 AMERICAN TELEGRAPHY. A slight modification has somewhat recently been made in the construction of thecopper spirals. Formerly, the two spirals and the supporting rod were made separ-ately and were held together by screw nuts. In the modification, the lower… … DISTRICT TULEGRAPH ClkCLTI ?—COXXECTIONS. rod previously used. A short piece of straiglit wire is continued down, from the cen-tre of the upper spiral, and is dropped loosely into the top of the narrow spiral rod,thus dispensing with all screws and screw nuts. In a very short time after the cell…
Telegraph
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