A mint condition solid silver English, early 19th century highly engraved chain driven fusee pocket watch, with a rare duplex escapement made by the famous makers Desbois & Wheeler of London. The watch is very substantial, and in a 2.5 oz silver consular case, so requires a secure pocket. This fine silver duplex fusee watch just cleaned and overhauled by my watch-maker on the 4/03/2008 and keeping good time. The watch with a very rare brass and steel (bi-metal) temperature compensation curb and a large sized solid 9k gold balance wheel. Clearly an attempt at improving the time-keeping of the frictional duplex escapement. A discussion and references to temperature error and compensation curbs can be seen at, http://en.wikipedia.org/wiki/Balance_wheel.
John Harrison was the first person to apply temperature compensation to a balance wheel in 1753, using a bimetallic ‘compensation curb’ on the spring, in the first successful marine chronometers, H4 and H5. These achieved an accuracy of a fraction of a second per day, remarkable for the 18th century and of great benefit to Longtitude. The more usual form of compensation curb is an elongated U with one curb pin fixed to the free end of the strip, which is caused to move away from (in cold) or closer to (in heat) the other pin, thus varying the play of the spring between the pins and roughly compensating the effects of temperature on the steel balance spring. The U form of compensation curb is associated with Breguet and was in fairly common use in France in the earlier part of the 19th century. It was fixed to the index as in the watch described here.
See for example, the web-site, http://home.datacomm.ch/rbu/C2.html. This is a beautifully made English key-wound mans substantial duplex pocket watch, dating from ca. 1822, from the late Regency period with a rare temperature compensation curb and large solid uncut gold balance wheel. The watch is clearly marked silver and in a consular case. The watch is in full working order and comes complete with a key for winding and presentation box
THE DIAL: 100% mint, , the ivory colored enamel dial with fine black Roman numerals, and a separate minute track to outside of dial with no chips or hairlines and large subsidary seconds dial. With gold spade hour and minute hands. The original glass in very fine condition. Diameter is 48 mm.
THE MOVEMENT: 100% mint, with richly gilded full plate in wonderful condition. The balance cock and foot in superb condition and of a simple pattern, but beautifully engraved. The balance cock with a large diamond end-stone to the centre of the balance cock. The back plate with further decoration and a u-shaped bi-metal temperature compensation curb. The watch is keywind, and movement size is 41 mm diameter. The escapement with a brass duplex escape wheel with a very good and strong action and jewelled to this wheel. The watch further jewelled with jewels to the duplex escapement and the 3rd wheel. The movement with round ballustar pillars and signed by the maker, Desbois & Wheeler of London and number 3440. Pierced gilded fusee stop work with iron hinge. The watch with fusee chain on tight to barrel and fusee cone and a good free swinging balance and the watch runs the full length of the fusee chain, keeping good time. The watch comes with a winding key for hands set and winding.
THE MAKERS: The makers Desbois and Wheeler were active in London during the period 1790-1835 and were noted watch makers. Their premises in the late 1820's was 10, Brownrow Street, London and by the early 1830's they had moved to Gray's Inn Passage, London. The business appears to have been carried on by Daniel Desbois through the later part of the 19th century. See also the following web-site for more information; http://www.nationalarchives.gov.uk/nra/searches/subjectList.asp?subjectType=R&LR=76&_AbsolutePage=7 for Daniel Debois & Sons, watch-makers of London. The guild-hall library also hold the company accounts for this company from the 19th century, so well worth investigating further.
THE CASE: 100% mint,the solid silver case measures an impressive 54 mm outside diameter. The hinged covers all closing tightly, and in fine order. The three knuckle hinge in good order. The cases with London hall-marks, case maker marks and silver sterling marks and a small silver "touch mark". The case maker mark of "TG". The pendant and very well made silver, in superb condition. The case with no pin-holes or stretch marks, to the case. The rear cover with fine quality rose engined turned engraving in crisp condition with a monogram in the shield to the centre. The inner dust cuvette also in very clean and good order.