Keywords: Balance Wheel in Early Watch Berthoud.png Illustration of a balance wheel in an early watch by Ferdinand Berthoud Alterations Detail cropped from drawing showing entire watch disassembled Downloaded from http //books google com/books id BykJAAAAIAAJ Ferdinand Berthoud 1805 L'art de Conduire et de Regler les Pundules et les Montres J M Eberhardt Paris Plate 2e on Google Books Published 1805 Ferdinand Berthoud Public domain the author died in 1807 PD-old Ferdinand Berthoud Balance springs Balance wheels Old horology prints |