John Arnold, London

• gilt full plate movement with Arnold short spring detent, free-sprung OZ balance, gold helical spring, decoratively pierced and engraved balance cock, turned pillars • white enamel dial, Roman numerals, outer Arabic minute ring, subsidiary seconds divided into 75 • gold consular case engraved with flowers and foliage, engraved musical instruments to the back within an ovoid reserve, pulse piece to the band at 8 o'clock, the back opening to reveal a plain polished fixed cuvette with winding aperture, case with maker's mark ITP for John Terrill Pain and hallmarked 1782, dial signed and numbered 88 • movement signed John Arnold London, Inv. et Fecit No. 39/88

Sotheby's London, The Edward Hornby Collection, 1st December 1978, Lot 67 p. 53 and the Cover

Vaudrey Mercer, John Arnold & Son, Antiquarian Horological Society, 1972 pp. 73, 79-80,89 and 210, pls.99-101

Terence Camerer Cuss, The English Watch 1585-1970, pl. 169

John Arnold refers to Arnold no. 39/88 as the “the Best Kind.”  The movement is one of only a handful that exist with their original short spring detents and it is the earliest form of spring detent that Arnold used.   No.39/88 is the only Arnold with the short spring detent to retain its original case. Arnold reserved the term for "The Best Kind" for his large chronometers.  Whereas "The Second Kind" were reserved for watches of smaller size and had an entirely new number series

Arnold did fit a pivoted detent to a series of chronometers up until 1782-83. 

The movement has an OZ balance which Arnold used from 1782-1791 however, it may have started with a double S balance The dial is the traditional layout, the seconds ring is divided into 75.  The escapement unlocks every other beat of the balance, allowing the hand to fall consistently on each division, leading to a more accurate reading.