Made in 1909 by the Ulm watchmaker Wilhelm Rössle (1866-1933).

 

Ca. 159 x 50.5 x 24 cm.

The clock offered here, manufactured and signed by Wilhelm Rössle with Glashütte components, combines the highest quality clock components of the time for improved accuracy and for the perfection of precision pendulum clocks - the free escapement by Ludwig Strasser and the temperature-compensated nickel-steel pendulum by Sigmund Riefler. As it was not uncommon for watch factories and watchmakers to purchase or supply individual components, it was possible to manufacture and further develop precision watches with the best precision mechanics. Wilhelm Rössle (1866-1933) was a clockmaker from Ulm and master clockmaker (1930-32) with a clock and goldware store in Platzgasse 5. After his death, the Ulm Museum acquired his extensive collection of grandfather, wall, saddle and travel clocks as well as pocket watches, dials and pocket watch movements from the 16th to 19th centuries, which provides a comprehensive overview of the history of the development of clocks. Ludwig Strasser (1853-1917) was one of the most important Glashütte watchmakers. Director of the German Watchmaking School in Glashütte from 1885, he founded the mechanical workshops Strasser & Rhode together with Gustav Rhode as early as 1875, which mainly produced precision pendulum clocks, measuring instruments and marine chronometers and supplied astrophysical observatories, observatories and navies as well as the Imperial Navy. Around 1897, he developed the free spring escapement for seconds pendulum clocks, the so-called "Strasser escapement", which was later named after him and patented. It has an anchor with double claws and a single gear wheel. The pendulum spring provides the driving force for the pendulum and thus provides the necessary energy supply to keep the pendulum swinging. The pendulum used in this clock is an Invar pendulum by Sigmund Riefler (1847-1912), one of the most important engineers, physicists and inventors in the field of precision clockmaking. The son and successor of the renowned clockmaker and precision mechanic Clemens Riefler (1820-1876) dedicated himself to the development of new measuring and drawing instruments as well as the improvement of timekeeping devices and precision clocks. In close cooperation with scientific institutes, observatories and time services, Riefler strove to improve the escapement and the pendulum, as the regularity of the rate depended largely on both. With his "free spring force escapement" patented in 1889 and his innovative mercury compensation pendulum developed in 1891, he was finally able to significantly improve the rate accuracy of precision pendulum clocks. After Charles Édouard Guillaume discovered a special nickel-iron alloy in 1896, Riefler was able to replace the mercury compensation pendulum and significantly simplify the type of temperature compensation. However, as the new pendulum rods made of nickel-iron alloy showed clearly detrimental thermal effects on the rate behavior due to residual molecular stresses, Riefler developed a complex reworking process in which the expansion coefficient of each individual rod was determined and the rods were reworked in a specially designed annealing furnace for 20 days. Due to the resulting outstanding properties and long-term stability of the pendulum rods, Riefler achieved an engineering masterpiece. From 1907, this nickel-steel alloy became known as Invar, derived from "invariable" (unchangeable). A total of 4104 Invar pendulums were produced, but Riefler himself only had 635 of them installed in Riefler watches. The majority were purchased by other companies, including Siemens, Bürk & Söhne, Junghans, Lenzkirch, Neher and many others. Ludwig Strasser acquired 82 Riefler pendulums for Strasser & Rhode to install in his best astronomical clocks.

Literature : Cf. Klassik Uhren 6/2000, fig. 11a,b), illustration of movement and dial with caption: "Pendulum clock 1st quality with Strasser escapement; raw movement and Riefler K pendulum 969 were delivered to Rößle, Ulm, in 1908". Die Uhrmacher-Woche, No. 32, 1934, p. 430 and Die Uhrmacher-Woche, No. 42, 1934, p. 555. Huber, Bernhard: Ingenieur der Präzision, Pendeluhren von Sigmund Riefler, pp. 7-43, in: https://uhren-muser.de:8080/chronohype/ChronoHype-Magazin_Nr_4.pdf. https://www.glashuetteuhren.de/die-uhrenfabriken/strasser-rohde-von-1875-1917/.

Provenance : From a private household in Thuringia.

Shipment on request.