Automatic winding

An automatic or self-winding watch winds its mainspring from the wearer's movements, by a weight that swings or turns inside the case and drives the winding gears through a ratchet.^1, 6

Richard Watkins's study of 1773 to 1779 concludes that Abraham-Louis Perrelet of Le Locle made the first practical self-winding watch, with a side weight, at the end of 1775 or early 1776; Wikipedia, following the Geneva Society of Arts report of 1777, says fifteen minutes' walking wound it for eight days.^1, 2, 7

The full rotor came from Hubert Sarton of Liège, who sent a watch to the Paris Académie in 1778. Watkins calls the idea that Perrelet invented the rotor 'the Perrelet myth', repeated since Chapuis and Jaquet's book of 1952.^1, 2

Names get confused in the record: the Swiss historical dictionary notes that the watchmaker Jacques-Frédéric Houriet was apprenticed to Abraham Louis Perret, 'not Perrelet'.⁸

Abraham-Louis Breguet in Paris took up the side-weight design about 1779 and sold his perpétuelles from 1780.^2, 9

For more than a century afterwards self-winding watches were rare luxuries, Watkins and Wikipedia agree, until the wristwatch gave them a purpose; in the meantime Coviot patented the rotor afresh in 1893.^1, 2

In the 1920s the wristwatch revived the idea: Léon Leroy with a side weight in 1922, John Harwood with a centre weight swinging between buffers, patented from 1923 and made by Fortis from 1926.^1, 3, 4

Harwood's point was sealing as much as convenience: with no winding stem through the case, his patent says, the case becomes 'practically dust and waterproof', linking self-winding to water resistance.^6, 11

Around 1930 the field crowded. Swiss patents of 1929 to 1931 for self-winding wristwatches were filed by the Harwood company, Bulova, the Perpetual Self-Winding Watch Co., Léon Hatot (whose 'Rolls' moved the whole movement), Wyler and others.^1, 12

Wikipedia says Glycine's founder Eugène Meylan designed a self-winding module for almost any 8.75-ligne movement as Harwood's patent neared its end; Glycine fitted it from October 1930.^13, 14

Rolex says it invented and patented the Perpetual rotor in 1931, a weight turning a full 360 degrees; Wikipedia says it gave up to 35 hours' reserve. The Swiss dictionary dates Rolex's rotor watch to 1930.^{1, 15, 16}

Watkins reports that Hans Wilsdorf sponsored Chapuis and Jaquet's history of self-winding watches, and Rolex printed copies of its English edition; he suggests Wilsdorf wanted the rotor to be seen as a Swiss invention.²

Later refinements: Eterna's ball-bearing rotor of 1948, by both the Swiss dictionary and Wikipedia, and bidirectional winding. Adrien Philippe's slipping mainspring bridle of 1863 prevented overwinding.^1, 17