Patent-Invent: Felix Savart

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Felix Savart: Co-originator of Biot-Savart Law

Felix Savart, (1791- 1841), a French physicist, taught at the Collège de France from 1828, becoming a professor there in 1836. He collaborated with Jean Baptiste Biot on a theory of magnetism. Magnetic fields produced by electric currents can be calculated using the law discovered in 1820 by Savart in his joint work with Biot. They took magnetism as the fundamental property rather than the Ampère approach which treated it as derived from electric circuits. This theory is known as Biot-Savart Law.

However, most of his research dealt with acoustics, including Savart's wheel, which he used for research on the lower frequency limit of hearing.

Demonstrations with Savart's wheel ought to convince anyone of the source of sound. The wheel is set spinning, and a playing card or a file card is held against the serrations on the rim of the wheel. At very slow rotation rates, the eye can see the edge of the card moving, but at higher rates it blurs, and a tone is produced. The frequency is directly proportional to the rotation rate. If some sort of counter were provided, Savart's wheel can be used, along with a stopwatch, to find the frequency of the sound. Thus, like the siren, it can be used for the absolute determination of pitch.

Felix Savart's Wheel - Hampden-Sydney College
The savart is a unit, called after Felix Savart, used in music to describe the ratio in frequency between notes. There are 301 (sometimes 300) savarts in an octave. This means two notes differ by one savart if the higher note has a frequency equal to 2^1/301 = 1.002305 times the frequency of the lower note.