For three similar watches by John Roger Arnold using Prest's keyless winding system, but all in silver cases, see:
Sotheby's London, 17th December 1987, lot 175: J.R. Arnold no. 20, hallmarked 1820
Sotheby's London, 26th February 1998, lot 35: J.R. Arnold, no. 30, circa 1820
Sotheby's London, 10th December 1981, lot 142: J.R. Arnold no. 91, hallmarked 1823 - now in the Patek Philippe Museum, [Inventory S-833] and published in Peter Friess, Patek Philippe Museum, The Emergence of the Portable Watch, Vol. IV, 2015, p. 611.
Thomas Prest's keyless system is discussed, together with an illustration of his patent drawings, in an article by Michael Gibbons for Antiquarian Horology: English Keyless Winding Watches [see op. cit. No. 4, Vol. 27, June 2003, p.424-426]. The patent only allowed for the winding of the watch and not the hand-setting – this watch is therefore fitted with an unusual minute hand that has a pin hole approximately 2/3 of the way down its length to aid adjustment with, presumably, a tool (quite possibly fitted to the top end of the original winding key) with short protruding pin to avoid the risk of scratching the dial’s surface. The development of keyless winding was one of the greatest advances in mechanical horology and Prest's system marked an important step in its evolution.
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