The wristwatch, as we know it today, is a marvel of miniaturized engineering. For most of its modern existence, the convenience of a self-winding mechanism has been taken for granted. A simple flick of the wrist is all it takes to power the intricate dance of gears and springs that keep time. But this effortless functionality was born from decades of frustration and the singular vision of an English watchmaker who sought to solve a problem that plagued every timepiece of his era: the winding crown.
Before the automatic revolution, a watch was a demanding companion. Every day, its owner had to meticulously turn the small crown to tighten the mainspring, breathing life into it for another 24 to 36 hours. Forgetting this daily ritual meant a dead watch. More critically, the crown and its stem created a necessary but vulnerable opening in the watch case. This tiny aperture was a gateway for the watch’s greatest enemies: dust, dirt, and moisture. These contaminants could clog the delicate movement, corrode parts, and turn a precision instrument into a useless piece of metal. The dream of a watch that could wind itself was not just one of convenience, but of longevity and reliability.
The Dream Before the Wrist
The concept of a self-winding timepiece wasn’t entirely new. As far back as the 1770s, the legendary Swiss watchmaker Abraham-Louis Perrelet had developed a self-winding mechanism for pocket watches. His system used an oscillating weight that would move up and down with the motion of the wearer’s walking. This ‘pedometer’ winding system was ingenious but was designed for the larger, more stable environment of a waistcoat pocket. Translating this idea to the smaller, more erratic world of the human wrist presented a far greater challenge.
The movements of the wrist are faster, more sporadic, and occur in multiple directions. A simple up-and-down weight wouldn’t be efficient enough. Several inventors tinkered with ideas, but none could create a reliable and commercially viable system. The problem lay dormant for over a century, waiting for the right mind to approach it from a new angle.
John Harwood’s Moment of Insight
That mind belonged to John Harwood, a watch repairer from Bolton, Lancashire, who later moved to the Isle of Man. Born in 1893, Harwood served in the British Army during World War I. It was in the trenches, witnessing the harsh conditions that soldiers’ watches endured, that he became acutely aware of their fragility. After the war, he returned to his trade, and the daily task of cleaning and repairing movements damaged by dust and water solidified his resolve. He saw the winding stem not as a feature, but as a fundamental design flaw.
Harwood’s genius was in realizing that the solution to a better, more sealed watch case was to eliminate the winder entirely. To do that, he needed a reliable automatic winding system. He began experimenting in his small workshop around 1922. His design was radically different from Perrelet’s. He envisioned a pivoting weight at the center of the movement that, instead of just moving up and down, would swing back and forth in an arc. This weight, or rotor, would transfer its kinetic energy to the mainspring through a series of gears.
The Birth of the ‘Bumper’
The system he perfected was elegantly simple yet robust. A semi-circular piece of brass was pivoted at the heart of the movement. As the wearer moved their arm, this weight would swing through an arc of about 270 degrees. At the end of its travel in either direction, it would strike a small, spring-loaded buffer, or bumper. This impact would make the weight rebound, creating a continuous back-and-forth motion that efficiently wound the mainspring. This characteristic ‘bumping’ action gave the mechanism its famous nickname: the ‘bumper’ automatic.
John Harwood filed his application for a patent with the Swiss Federal Office for Intellectual Property in Bern on October 16, 1923. He was granted Swiss Patent No. 106583 in September 1924 for his pioneering self-winding wristwatch design. With financial backing and partners, his watches were first presented to the public at the Basel Fair in 1926, marking the dawn of the automatic wristwatch era.
To realize his vision, Harwood needed the expertise of the Swiss watch industry. He partnered with Swiss manufacturers Fortis and A. Schild S.A. (ASSA) to bring his invention to life. ASSA developed the movement based on his designs, and Fortis handled the assembly and marketing. The world’s first successful self-winding wristwatch was finally ready.
A Watch with No Crown
The Harwood watch was revolutionary not just for what was inside, but for what was missing on the outside. It had no winding crown. This gave it a smooth, perfectly round, and more water-resistant case. But this created a new problem: how do you set the time? Harwood devised another clever solution. The bezel, the ring around the watch crystal, could be rotated. Turning it in one direction would engage the hands with the movement, allowing the time to be set. A small dot in an aperture on the dial, just above the 6 o’clock position, served as an indicator: it showed white during normal running and turned red when the hand-setting mechanism was engaged. It was an intuitive and elegant system that completely sealed the watch case from the elements.
The Harwood watch was a commercial success, heralding a new age for horology. Other brands, like Blancpain, soon followed with their own interpretations based on Harwood’s patents. For a few glorious years, Harwood’s design was the pinnacle of watchmaking technology.
Rolex and the Perfection of the Rotor
While Harwood’s bumper system was a triumph, it wasn’t the final word. The bumping action, while effective, was somewhat inefficient as the rotor could not complete a full circle. It also created a noticeable jarring sensation on the wrist. The next great leap came in 1931 from a company that would become synonymous with automatic watches: Rolex.
Rolex, led by the marketing-savvy Hans Wilsdorf, had been working on its own self-winding system. Their innovation, which they dubbed the ‘Rolex Perpetual’, built upon Harwood’s concept but perfected it. Instead of a rotor that bumped back and forth, Rolex developed a centrally mounted, semi-circular weight that could rotate a full, uninterrupted 360 degrees. This unidirectional rotation was far more efficient at capturing the wearer’s motion and wound the mainspring more smoothly and silently. It was this full-rotor system that would become the undisputed industry standard, a design still used in the vast majority of automatic watches today.
Rolex marketed their Perpetual movement brilliantly, often billing it as the world’s first automatic wristwatch, a claim that somewhat unfairly overshadowed Harwood’s foundational achievement. While Rolex undoubtedly perfected the concept and made it the global standard, it was John Harwood who first solved the puzzle and successfully brought a self-winding wristwatch to market.
An Enduring Legacy
John Harwood’s contribution to watchmaking is immense. He didn’t just invent a convenient feature; he fundamentally changed watch design for the better. By eliminating the weakest point of the watch case, he paved the way for the truly robust and reliable tool watches—the diver’s watches, pilot’s watches, and field watches—that would become indispensable in the decades that followed. His ‘bumper’ automatic may now be a relic of a bygone era, cherished by collectors, but the principle he established—harnessing the simple, unconscious movements of the wearer to power a complex machine—remains at the very heart of mechanical watchmaking.
