THOMAS PREST, LONDON | AN EXCEPTIONAL AND VERY RARE GOLD OPEN-FACED SPLIT SECONDS CHRONOGRAPH WATCH WITH APERTURES FOR HOURS AND MINUTES, WITH GOLD AND LAPIS LAZULI CHAIN AND KEY1840, NO. 527

• Movement: gilded full plate key-wound movement, bi-metallic compensation balance, diamond endstone, chronograph mechansim visible to under-dial with recessed barrel pivoted around fourth wheel seconds pivot, spiral spring surmounted by seconds hand • signed and numbered Tho. Prest London, No. 527 • Dial: gilt dial with engraved scroll and foliage decoration, two fan-shaped apertures for the wandering Arabic minutes and Roman hours, large subsidiary seconds dial with two blued steel splitting hands • Case: engine turned outer, pusher through the crown to split the seconds hands, movement stop slide beneath bezel, hallmarked London 1840, plain polished gold cuvette, case back and cuvette with casemaker's mark HH incuse (possibly Henry Hardy)• Chain: short gold chain, the links separated by lapis lazuli roundels terminating in a key in the form of a T-bar

L. E. Christmas, A.M.I. Mech. E., A.F.R.Ac.S., 1963
Sotheby's London, 1 October 1997, lot 27
Christie's Geneva, 12 November 2007, lot 205

Antiquarian Horological Society's 10th Anniversary Exhibition, Science Museum, London, 1964

Paul Tuck, Horology under the Hammer, Antiquarian Horology, No.5, Vol. 24, Spring 1999, p.447
L.E. Christmas, A Watch by Thomas Prest, Antiquarian Horology, No.2, Vol.4, March 1963, p.47

MVT: Running at the time of cataloguing. Split function operational. The plate with a light spot of discolouration beneath the signature, and some light oxidation to the blued elements. CASE: The case with some wear. Light surface scratching throuhgout. Engine turning with some rubbing to the band and case back to be expected given age and use. Marks to the inside case back and cuvette clear and defined. Hallmarks with some rubbing. DIAL: engraving is very crisp and defined. The engine turning to the seconds ring has some marks but overall very good condition. Please note that the movement has not been tested for the accuracy of time and may need a service at the buyer's expense. Sotheby's does not guarantee the future working of the movement and we do not guarantee the authenticity of any individual component parts since subsequent repairs and restoration work may have resulted in the replacement of original parts. You are advised that watch straps or bands made of materials derived from endangered or otherwise protected species (i.e. alligator or crocodile) are not sold with the watch and we reserve the right to remove these straps or bands prior to shipping. Furthermore, the watch may not come with its original manufacturers strap or band. Prospective bidders should review the Conditions of Business, Authenticity Guarantee, the Guide for Prospective Buyers, and any Important Notice in the sale catalogue.
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. All dimensions in catalogue descriptions are approximate. Condition reports may not specify mechanical replacements or imperfections to the movement, case, dial, pendulum, separate base(s) or dome. Watches in water-resistant cases have been opened to examine movements but no warranties are made that the watches are currently water-resistant. Please note that we do not guarantee the authenticity of any individual component parts, such as wheels, hands, crowns, crystals, screws, bracelets and leather bands, since subsequent repairs and restoration work may have resulted in the replacement of original parts. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue. In particular, please note it is the purchaser's responsibility to comply with any applicable import and export matters, particularly in relation to lots incorporating materials from endangered species.NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

**Please be advised that bands made of materials derived from endangered or otherwise protected species (i.e. alligator and crocodile) are not sold with the watches and are for display purposes only. We reserve the right to remove these bands prior to shipping."

Thomas Prest was apprenticed to John Roger Arnold in January 1784, he became the latter's foreman before leaving to conduct business by himself sometime around 1820. Prest is best known for a patent he was granted (no.4501, 20 October 1820) for an early form of keyless winding system. In an article for Antiquarian Horology where the present watch is discussed (No.5, Vol. 24, Spring 1999, p.447), Paul Tuck notes that: "A lesser known fact is that he [Prest] was one of the first to devise a form of split seconds chronograph mechanism. Only a handful of these are known, this [no.527] being the finest example."  A most unusual watch which clearly demonstrates Prest's skill and creativity, its refinement has led to the suggestion that Prest may have worked for Breguet early in his career (see op. cit. p.447). Depressing the pusher in the pendant splits the seconds hands within the large subsidiary dial, this stops one of the seconds hands whilst the other continues to run; when the pusher is released, the second hand that is static flies back to join the running hand. A difference of 25 seconds may be measured before an arm on which one end of the spring to which the seconds hand is attached engages a pin to the underside of the plate to prevent the spring from being overwound.