Self-winding mechanisms were applied to pocket watches as early as the 18th century, but the advent of wristwatches in the 20th century posed new challenges to watchmakers. Mechanisms were smaller and subject to more shocks, and winding crowns were an easy entry point for water and dust to get into the movement. John Harwood, a watch repairer from the Isle of man, became frustrated with the obvious design faults of the early wristwatches and set about finding a way to make a watch without the need for winding crown. In 1924 he dveloped and patented the first practical self-winding wristwatch mechanism, of which this is an example.
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