page_title: Savart wheel
section_title: Savart's version
hierarchical_section_title: Savart wheel / Savart's version
caption_attribution_description: Savart's apparatus for numbering vibrations
context_page_description: The Savart wheel is an acoustical device named after the French physicist Félix Savart, which was originally conceived and developed by the English scientist Robert Hooke.
  A card held to the edge of a spinning toothed wheel will produce a tone whose pitch varies with the speed of the wheel. A mechanism of this sort, made using brass wheels, allowed Hooke to produce sound waves of a known frequency, and to demonstrate to the Royal Society in 1681 how pitch relates to frequency. For practical purposes Hooke's device was soon supplanted by the invention of the tuning fork.
  About a century and a half after Hooke's work, the mechanism was taken up again by Savart for his investigations into the range of human hearing. In the 1830s Savart was able to construct large, finely-toothed brass wheels producing frequencies of up to 24 kHz that seem to have been the world's first artificial ultrasonic generators. In the later 19th century, Savart's wheels were also used in physiological and psychological investigations of time perception.
  Nowadays, Savart wheels are commonly demonstrated in physics lectures, sometimes driven and sounded by an air hose.
context_section_description: Hooke's device was not used again for study purposes for over a century. Its next documented usage was in 1830 when Savart reported his use of a system similar to Hooke's which he developed while investigating the lower range of human hearing. Savart's specific contribution was to attach a tachometer to the axis of the toothed wheel to facilitate calibration of the tooth rate. Savart used his wheel as a practical alternative to John Robison's siren, which was also being adopted at the time by Charles Cagniard de la Tour to test the range of human hearing. By 1834 Savart was constructing brass wheels with a width of 82 cm, containing as many as 720 teeth. These wheels, which could produce frequencies up to 24 kHz, have been tentatively proposed as the first artificial generators of ultrasound.
caption: An illustration of a Savart wheel (from The Popular Science Monthly, 1873)[4]
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