I. researches in telephony

It has long been known that an electro-magnet gives forth a decided sound when it is suddenly magnetized or demagnetized. When the circuit upon which it is placed is rapidly made and broken, a succession of explosive noises proceeds from the magnet. These sounds produce upon the ear the effect of a musical note, when the current is interrupted a sufficient number of times per second. The discovery of “Galvanic Music,” by Page,
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in 1837, led inquirers in different parts of the world almost simultaneously to enter into the field of telephonic research; and the acoustical effects produced by magnetization were carefully studied by Marrian, †Beatson, ‡Gassiot,§DelaRive,|| Matteucci,
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Guillemin,† Wertheim,‡ Wartmann,§ Janniar,|| Joule,¶ Laborde,
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Legat,‡‡Reis,‡‡Poggendorff,§§ Du Moncel, || || Delezenne,¶¶ and others.
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