Letter | Published:

New Form of Microphone Receiving-Instrument

Naturevolume 18page194 (1878) | Download Citation



HAVING been experimenting with the microphone, and studying the effect of the passage of the current on a galvanometer, it occurred to me that if the needles were fixed, strains would be produced in it by the action of the current. To test this, I passed a few yards of copper wire (about No. 30) on a small bar magnet lengthwise, and found, on placing it to the ear, that sounds were heard on interrupting the current; these sounds were much intensified by placing the magnet inside the lid of a pasteboard box.

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  1. Glasgow

    • W. J. MILLAR


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