The Telharmonium

The Telharmonium was a machine for generating a kind of ``additive synthesis'' of musical sound for distribution over telephone lines. It is described in U.S. patent 580,035 by Thaddeus Cahill (1898), entitled

``Art of and Apparatus for Generating and Distributing Music Electrically''

Sound was generated electromechanically in the Telharmonium by means of so-called rheotomes, depicted in Figures H.1 and H.2. A rheotome was a spinning metal shaft with cut-outs that caused a periodic electrical signal to be picked up by capacitive coupling. The rheotome is a clear forerunner of the Hammond organ tone wheels, shown in Fig.H.3.

YouTube: Magic Music from the Telharmonium Documentary

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About the Author: Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.