U.S. patents covering time keeping mechanisms (1923)
United States. Patent Office · [Washington, D.C.] : U.S. Patent Office · leaf 734
Aug. 26, 1923. 1,466,653 F. BATTER TIMING APPARATUS FOR MOUNTAIN AIR SANITARIUMS Original Filed May 21 . 1920 3 Sheets-Sheet 1 iini ill i i ' … By Sffflf
Clocks and watches
Internet Archive · Smithsonian Libraries · Public domain (published before 1931). Free to use for anything.
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