Offered for your consideration this German Schatz 400 day anniversary clock , circa 1960s , Schatz & Sohne Germany model 49, dome and etched posts *** Weight: 4# 5 oz. - Measurements: 7.5 x 7.5 x 11.5. .......... The Schatz Clock company and the clocks they made have an interesting history. In the late 19th century, August Schatz was working with inventor Anton Harder and together they formed Jahresuhrenfabrik (Year Clock Factory) with the goal of making an accurate clock that only needed winding once a year. They were successful in making the 400 day, or Anniversary, clock but it wasn't as accurate as they'd hoped. Harding sold his patent is 1884 to F.A..L. deGruyter of Amsterdam and they continued to make Jahresuhrenfabrik clocks but for some reason they allowed their patent to expire. Other companies took up the challenge of making the 400 day clock more accurate. The pendulum for the 400 day clock was the reason it didn't need to be wound so often. A pendulum spun at the end of a suspension spring allowed it to run much longer between windings then the 8 days most clocks ran. The initial designs called for a flat disk pendulum which then evolved into the 4 ball pendulum that is still used today. American jewelers Bowler and Burdick marketed their 400 day clock as the Anniversary clock and it became popular for people to wind their clock on a special yearly event like a birthday or wedding anniversary. This also made the clocks popular gifts. The clocks were still relatively inaccurate. Experiments were done to try to figure the best materials to make the pendulum out of because the clocks were easily affected by humidity and temperature changes. This problem was solved when Charles Terwillinger of Horolovar Company invented the Temperature Compensating Suspension Spring in 1951. If this thin spring wasn't tuned just right it could throw off the best timekeeping engineering.