U.S. patents covering time keeping mechanisms (1892)
United States. Patent Office · [Washington : United States Patent Office] · leaf 561
QWtrVWL/ fa. (rffwfraAcii/ i PCTERS CO , PHQTO-UTHO . WASHINGTON (No Model.) 17 Sheets—Sheet 17. a. E. HUNTER. MECHANISM FOR TESTING WATCH BALANCES AND HAIR SPRINGS. No. 490,202. Patented Jan. 17, 1893.
Clocks and watches
Internet Archive · Smithsonian Libraries · Public Domain Mark 1.0. Free to use for anything.
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