May 21 - May 25

Figure 2. Left, an 18 size Hampden full hunter case pocket watch (ca. 1894). Right, a Longines 24-mm wide Art Deco-inspired rectangular wristwatch, ca. 1938. Note the considerable size difference between the watches.
Figure 3. The Harwood self-winding (automatic) wristwatch, ca. late 1920s, movement view. Made in Britain. Accessed May 13, 2016. http://madeupinbritain.uk/Automatic_watch
Self-Winding Technology
The first self-winding (automatic) wristwatch (Figure 3) was invented in 1923 by John Harwood,5 a British watch repairer. On September 1, 1924, the Federal Institute of Intellectual Property in Bern, Switzerland, awarded him a patent no. 106583. This invention helped revolutionize the wristwatch industry.
Harwood realized that dust and dampness in a wristwatch movement caused issues that led to malfunctions and inaccuracy. Because he knew that most of the foreign matter and moisture got into the movement through the winding stem, he eliminated it by putting a wristwatch’s winding mechanism inside its case. These early self-winding movements are now referred to as a “bumper” and “180 bumper.” They use a pivoting weight that winds the mainspring when the wearer moves his or her arm. Harwood said he was influenced by watching children play on a seesaw. A concern with this design is that the spring bumpers limit the swing to less than a full 360°.
The first Harwood automatic wristwatches were produced with the financial backing of Swiss watch manufacturer Fortis and went on sale in 1928. The Harwood Self-Winding Watch Co. produced 30,000 wristwatches before it was forced out of business in 1931 due to the Great Depression.
In 1931, Rolex improved Harwood’s concepts and invented a more reliable self-winding wristwatch mechanism, which allowed the semi-circular weight to rotate 360° (a patented winding system). Rolex’s new winding system eventually replaced the bumper winder design. When Rolex promoted its Oyster Perpetual wristwatch, which featured a 360° (full circular) rotor self-winding mechanism, the company erroneously claimed that it was the original inventor of the automatic mechanism on a wristwatch. Obviously, Harwood was the original inventor of the mechanism’s use on a wristwatch and was exasperated by Rolex’s claim. Harwood did receive a public apology from Rolex on June 10, 1956, in the London publication Sunday Express. It stated, “Mr. John Harwood of Harrow, Middlesex, was the inventor of the first self-winding wristwatch and we apologize for any injury to his feelings which may have been caused by our advertisement…”
The Rolex Oyster (Figure 4), introduced in 1926, was an airtight, dustproof, and water-resistant (often referred to in the literature and advertisements as…

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