5676330 Calendar watch, c.1780 (silver case) by American School, (18th century); Private Collection; (add.info.: The earliest known calendar watch made entirely on American soil, having Voight\'s double virgule escapement, with adjustable temperature compensation, special wheel work, and a silver case made for Francis Bailey. Movement signed Henry Voight, Philadelphia, dial signed Francis Bailey, Printer, Philadelphia. Case stamped with Voight\'s master mark \'HV\', movement No. 22.); Photo by Christie\'s Images.