German pocket watch with extremely rare onyx case Circa 1770

Golden Louis XV pocket watch
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A golden Louis XV pocket watch with an extremely rare onyx case, made by John Michael Bendele in Augsburg, Germany, circa 1770. The extremely decorative open faced stone case is made from pink gold and cut onyx and is cut in the shape of a rose. The Louis XV white enamel dial has an outer ring with black Arabic numerals for the minutes and an inner ring with black Roman numerals for the hours and exceptional diamond set hands. The beautifully decorated movement has a verge escapement and a chain/fusee.
The movement is signed and numbered,
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Diameter: 45 mm
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Weight: 74 g
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Signed: Johan Michael Bendele
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Johan Michael Bendele, born in 1734, was registered as a watchmaker in Augsburg around 1770.
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Another watch by John Michael Bendele, Augspurg, with an almost identical case, was offered in Geneva in October 1998 with an estimate of 1.000 to 14.000 Swiss francs
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A chain/fusee system is used to regulate the power transmitted from the mainspring to the watch movement. The purpose of this system is to ensure consistent and accurate timekeeping.

The chain/fusee system consists of two main components: the chain and the fusee. The chain is a flexible metal strip with small links that are connected to the mainspring barrel. The fusee is a cone-shaped device with a spiral groove. The chain is wrapped around the fusee, and as the mainspring unwinds, it pulls the chain, which in turn rotates the fusee.

The spiral groove on the fusee is designed to change the effective diameter of the fusee as it rotates. When the mainspring is fully wound, the chain is at its maximum length, and it pulls on the largest diameter of the fusee. As the mainspring unwinds and the chain gets shorter, it pulls on smaller diameters of the fusee.

This change in effective diameter compensates for the decreasing torque of the mainspring as it unwinds. By providing a more constant force to the watch movement, the chain/fusee system helps maintain a consistent rate of timekeeping throughout the power reserve of the watch.