Waltham Crescent Street Model 1870: Fogg’s Patent Pinion – February 14, 1865

On February 14, 1865, Charles W. Fogg received a patent for his “Safety Pinion.” While not the first patented safety pinion, Fogg’s design represents the first practical application utilized in mass production, allowing the watchmaking industry to improve the durability and longevity of watch movements. Prior to this implementation, movements were prone to damage beyond practical repair when the mainspring broke. Fogg’s design is arguably one of the most influential advancements in American watchmaking. ⠀
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The patent letters provide an explanation of the purpose and benefit of Fogg’s safety pinion design: “A great objection to that class of watches, where a going barrel is employed arises from the liability of the train to be damaged by the violent recoil resulting from the accidental breakage of the mainspring… It will thus be seen that the force of the recoil is prevented from being communicated to the train, as the pinion commences to rise on its arbor the instant that the force of the recoil is exerted to revolve it in a contrary to that in which it is intended to run, and no force is exerted on the train beyond what is necessary to start the pinion on its screw-arbor…”⠀
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When the Model 1870 was introduced, Fogg’s safety pinion was a standard inclusion at the Waltham factory. Tomorrow, we will take a closer look at a center safety pinion from our Model 1870 Crescent Street.