What year did Waltham start using Foggs patent pinions???

Fogg's Patent safety pinion (46,343 February 14, 1865) was shared with Elgin by Waltham and became part of the basis for the homogeneity that gave Waltham/Elgin primary control of the distributed watch movement market through the early 20th century.

The Waltham site mentions;

"American Watch Co. Grade KW16 is fitted with Fogg's patent vibrating hairspring stud . . . The serial number is 125,466 (ordered to production August, 1864).

The next major development in the 3/4 plate designs was a rearrangement of the pillars, the addition of Fogg's patent center pinion and a simplified winding click. These watches were produced in nickel finish as well as gilt."

This suggests the Fogg's Patent pinion entered the scene somewhere in late 1864 - Early 1865. Before that American Waltham) Watch Co. used a Fitt's patent pinion.

Thanks Dave..I am working on a 1862c. Waltham and it had a safety pinion on the center wheel. I didn't think it was right but I wasn't sure...I guess somewhere in its long life someone had replaced the center wheel...Thanks again...

Actually most safety pinions used from 1870(ish) on were Fogg's Patent type but simply marked "Patent Pinion" until (finally) that was dropped as well.