A wonderful quality and rare late 18th century movement, in almost mint condition.
MOVEMENT : Signed (F. Willis, London) and numbered (102).
Beautifully engraved and pierced balance cock, with diamond endstone and blued screws. Polished steel balance and escape wheels, and ruby escapement cylinder.
Protected by a removable gilt dustcap, signed and numbered as the movement.
MOVEMENT CONDITION : All in wonderful, almost mint, condition, with no scratches and the screw heads unmarked. Running well.
MOVEMENT SIZE : 6.5 mm between the plates. Top plate 33.5 mm. Dial plate 35 mm.
DIAL : White enamel, in mint condition. Gold coloured hands, the minute a little short. Complete with motion wheels.
DIAL SIZE : 36.8 mm. (dial false plate).
The ruby cylinder was used by Abraham Louis Breguet to reduce the friction in cylinder escapements. The cylinder itself is composed of a half tube formed ruby (sometimes sapphire), set into two steel plugs, each with a pivot. This was a very expensive innovation and is rarely found.