Important Watches, Wristwatches and c...

Geneva, Oct 15, 1989

LOT 306

Clement Riefler, Nesselwang, No. 709, produced in 1947. Extremely fine and rare astronomical observatory regulator in an evacuted container.

Suported by a heavy bracket, the movement is set under a glass dome which is sealed on a painted cylinder made of copper in such a way the vacuum can be produced by means of an air evacuating pump in order to maintain the pendulum close to a constant condition. Silvered engraved regulator dial, with a small off set Arabic chapter for 24 hours, symetrical subsidiary seconds and outer minute ring. Blued steel "spade" hands. Set under the dial, the remontoire is driven by a 10 g. weigh visible through an aperture on the dial. The weigh is rewound every 20 to 40 seconds according to the state of charge of the 4 volt battery. Riefler escapement with jewelled pallets and jewelled bearings in which the impulse is given via the suspension spring which is re-tensioned by the espacement at each swing of the pendulum. It is thus a constant force escapement in which the suspension spring is also the remontoire spring. The pallet frame is supported on knife edges from which the pendulum is also suspended. There are two es-cape wheels, one for locking and one for tensioning the suspension spring. Tempered and hardened nickel steel invar pendulum, Model J1, set with compensating tubes at a precise position from the lower end of the pendulum rod by means of a large knurled nut. The vertical position of the pendulum can be set and its amplitude observed by means of a micrometer. Riefler used to guarantee the compensation rate of such a pendulum to 0,002 sec a day per degree c. In very good condition. Dim. 154 x 40 x 38 cm.