Deutsche Uhrmacher Schule

Deutsche Uhrmacher Schule, Glashütte, Riefler, Münich, pendulum No. 2062, circa 1900. Very fine and rare mahogany wall regulator beating seconds, with regulator dial, invar pendulum and barometric pressure compensation. Rectangular, glazed on both sides and front, molded top, hinged glazed doors on both sides of the movement Round, silvered, Roman hour chapter set in the lower part, central minutes with five-minute Arabic markers, seconds set at 12 o’clock. Blued steel hour hand, index minute hand. Rectangular, brass, long duration by means of double pulley, Graham escapement with specially hardened steel pallets, spring suspension, invar rod pendulum with invar rod and pressure compensation attachment, micrometric length adjusting nut serving also as temperature compensation, micrometric beat adjustment on the crutch.Signed Riefler on the pendulum.Dim. Height 142 cm. Notes Invar’s coefficient of expansion is about 12 times lower than that of steel; therefore it needs very little compensation. The slight expansion of the pendulum rod is compensated by a steel or nickel nut. When the temperature rises, it very slightly lifts the bob to the exact extent to which the pendulum expanded downward. The center of gravity remains the same. In addition to temperature, air pressure also affects the oscillation time of a pendulum. Under rising air pressure the pendulum swings more slowly, and speeds up under falling pressure. To compensate for this Riefler invented a special device