A rare early 19th Century French calendar lever with two going barrels in a slim gold and silver open face case. Keywind gilt bar movement, two suspended going barrels wound independently by a male key. The barrels both drive the centre pinion, the teeth on one barrel situated above the teeth on the other allowing them to intersect without interference. Plain cock with blue steel regulator, the sector visible through the cuvette. Compensation balance with blue steel spiral hairspring. Unusual form of club foot lever escapement, double roller with triangular jewel impulse pin. Signed engine turned silver dial, offset chapter of Roman numerals, aperture for the date calendar above, steel lever under the front bezel to set the date. Gold Breguet hands set with the male key. Slim engine turned 18 carat open face case with applied engine turned silver band to the middle. Plain hinged gold cuvette with apertures to wind the twin barrels and sector to reveal the index. Blue steel dog screw which can be turned to lock the cuvette in place, maker’s mark “AB” in a diamond.