Historical German patents & torsion pendulum clocks. part I, DRPS 1877-1945 / D.K. Stevenson.
Historical German patents and torsion pendulum clocks. part I, DRPS 1877-1945
- 138 pages ; 30 cm
Clocks and watches--Patents--Germany--19th century. Clocks and watches--Patents--Germany--20th century. Torsion pendulum.
Clock (general) patent torsion Stevenson, Douglas K. Ruhrei