I. researches in telephony

Abstract

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,^* 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,^* Guillemin,† Wertheim,‡ Wartmann,§ Janniar,|| Joule,¶ Laborde,^** Legat,‡‡Reis,‡‡Poggendorff,§§ Du Moncel, || || Delezenne,¶¶ and others.^***