Rare, Ultra-Thin ‘Bayonet Caliber’ Movement

Cylinder Escapement, France-Switzerland, 1830 – 1840.

This early, extremely small and ultra-thin movement is absolutely in the category of special collectable delights. 150 years ago, the ability to produce miniature watch movements by hand was accessible only to elite watch manufacturers. Reducing the size by one and a half to two times involved a 10-fold increase in the time and cost of manufacturing. The equipment was manual, and it was a struggle to achieve literally every tenth of a millimetre. Because of this, ultra-flat watches (also called ‘medallions’) were considered particularly prestigious and were housed exclusively in gold cases, as gold is easier to process into a durable thin sheet than other metals.

The thickness of the mechanism between the plates is 2.2 mm.

Enamel dial, gold hour hand. The minute hand is lost.

The back plate of the mechanism is also an internal cover. The board is very thin, and the engravings are applied by hand before the final hole cutting.

“Echappement a cylindre six trous en rubis” – cylinder escapement, 6 holes with rubies.

“Aiguilles” – hands (the hole for the key to move the arrow).

“A / R-avance retard” – faster-slower (strike control).

The most amazing thing is the arrangement of the mechanism and the arrangement of the parts. In the pursuit of fractions of millimetres, the mechanism is literally turned inside out. All the details are placed under the dial. What is especially surprising is that the cylinder balance axle has a rather complex design, and is all packed into just 2 mm. The stroke precision regulator is mediated with a comb, with the output through the rear plate. The jewels are natural ruby, and very thin. The entire wheel system rotates in reverse: the cylinder running wheel rotates counterclockwise (this does not happen anywhere else!!!). A special reversible trib is provided to drive the hour and minute wheels. The finishing of the parts is of the highest-quality, everything doesn’t just shine – it sparkles!

Watchmakers were able to construct this more than 150 years ago. The mechanism is in generally good condition, it will run for almost two days after a full wind.

Additional Materials:

Gold watch with the same mechanism in the Stephen Bogoff collection.