As with any intricate machine containing delicate parts, dust and foreign particles can greatly affect the performance and potentially damage a pocket watch movement. This is especially true for full plate models, where the mechanics are fitted between two large plates, leaving ample space for dust and particles to easily enter the works.
Over the decades, numerous patents were issued for innovative devices to prevent dust from entering the movement. B.D. Bingham’s simple design was one of the first dust rings to receive a patent, issued on February 4, 1868. Bingham developed the dust ring while he was associated with the Tremont Watch Company. The primary improvement claimed over similar devices was the tight friction-fit ring, allowing easy installation and removal without screws.
Shortly after the patent was issued, the Tremont company failed, and the American Watch Company began fitting Bingham’s dust ring on Waltham movements. As exhibited in the accompanying photograph, Bingham’s dust rings can be easily identified by the patent date stamped on the outer perimeter: “Patent Feb. 4, 1868.”