Very fine Swiss 18K gold cabriolet pocket watch Circa 1855

Gold cabriolet watch by Vacheron & Constantin
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A very fine Swiss 18K yellow gold cabriolet-type pair-cased open faced key-winding pocket watch, circa 1850-1860. Then named boîte à étui tournant.
Lever movement, lateral lever escapement, monometallic balance. Case and outer case engraved in taille-douce (fine-cut) with foliage. White enamel dial with Roman radial hours, outer minutes track, and Breguet-style hands. Accompanied by a winding key.
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Diameter: 44 mm
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Signed: Vacheron & Constantin, Geneva
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Boîte à étui tournant or cabriolet-type case
The boîte à étui tournant is a cabriolet-type case or a pair-case watch. In the pair case (or étui), one should place the watch in one way or the other. If the dial side of the watch is presented in the open part of the pair case, this one becomes an open-face watch. On the other hand, if the watch’s case back is presented, it becomes a hunting case watch. This protects the glass when the watch is worn in the pocket. This type of case seemed to have been created by Abraham-Louis Breguet (1847–1823), circa 1810, especially for his watches made for the Turkish market. This type allows a decor en suite, more or less rich, of the two boxes.