
Leroux. A fine and very rare late 18th century pocket watch movement with temperature compensation Numbered 3102, Circa 1781
Sold for £9,375 inc. premium
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Leroux. A fine and very rare late 18th century pocket watch movement with temperature compensation
Fusee movement with large steel three-arm balance, conical balance spring, large bi-metallic 'chelsea bun' type compensation, pivoted detent escapement, enamel dial with offset hour and seconds dials, outer minute track, 'faster slower' indication at 6, with later silver jointed case (AF)
Dial 50mm.
Footnotes
There are very few surviving and recorded Leroux pocket chronometers. It is highly probable that the conical balance spring was Leroux's means of evading Arnold's patent for the helical spring but achieving similar isochronal advantages.
No.3107, also with a pivoted detent escapement, is in a gold case hallmarked 1781/2, though it appears to have lost its 'Chelsea Bun' compensation mechanism, which was probably the same as that in No.3102.
No.3102, which thus dates from c.1781, also appears to have an additional compensation in the form of a bimetal curb acting on the balance spring. Just as Leroux was probably avoiding Arnold's patent for the helical balance spring, he may have fitted this form of compensation owing to Arnold having patented the compensation balance.
Pocket watch No.3137 by Leroux is in a silver gilt case hallmarked 1784/5 (apparently with a cylinder escapement) which also has what appears to be Chelsea bun compensation (sold by Gardiner Houlgate, Bath 2 June 2005).
Then, in about 1786/7 Leroux made the watch with lever escapement No.3153 now in the BM collection, (movement only), which has a form of compensation balance.
It seems likely the '31xx' series was used by Leroux for experimental precision watches.
We are grateful to Jonathan Betts from the National Maritime Museum for assistance in the research on this movement.