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An Englishman and electrical engineer by trade, William DuBois Duddell is best known for inventing the Singing Arc, one of the first electronic musical instruments. He also invented several other machines involving electrical current, such as the electromagnetic oscillograph, an instrument for measuring and recording current and voltage; the thermo-galvanometer, a device for measuring antenna currents, which is still in use today; and the moving coil oscillograph, designed for photographic recording and observation of oscillating frequency waveforms.
Duddell accidentally happened upon the Singing Arc while working on a problem with streetlights in London in 1899. At that time, European cities were lit by the carbon arc lamp, which generated light by creating a spark between two carbon nodes. A byproduct of this process was an annoying humming sound. Duddell’s task was to eliminate this noise. While conducting experiments to solve the problem, Duddell discovered that he could create controllable audio frequencies by varying the voltage powering the lamps. By attaching a keyboard controller and special circuits to the arc lamps, the operator could change the arc’s rate of pulsation, producing distinct musical notes. While not the first electrical device to be used to create tones or music, Duddell’s invention was one of the first instruments that could be played without making use of the telephone system as a receiver, as Thaddeus Cahill’s bulky Telharmonium did. He soon exhibited the Singing Arc to a group of electrical engineers in London. During this exhibition it was noticed that arc lamps operating nearby and drawing on the same power source as Duddell’s instrument also played the music. This effect was later found to be even more useful when an antenna was attached to the Singing Arc, which allowed it to “sing” at radio frequencies rather than audio. Duddell’s creation did not translate into commercial success, however. He did not patent it and although he toured England with his invention, the Singing Arc never attained more than novelty status.
Duddell served as President of the IEE (Institute of Electrical Engineers) in 1913, and was also a trustee of the Benevolent Fund. The Duddell Medal was instituted in 1923 by the Council of the Physical Society as a memorial to him, and is awarded annually to someone who has contributed to scientific knowledge through the application of physics.