Rare complete cased example of this unusual Robin-type escapement.
Silver engine-turned case hallmarked 1861, casemaker TH (Thomas Holliday, Clerkenwell). Caped fullplate fusee movement with cap jewels on balance (diamond) and escape, the cap stamped SW. London Patent escapement, a single impulse detached escapement, as first published by Robert Robin in Paris in 1791. Compensation balance, spiral balance spring. Enamel dial signed CHRONOMETER 1421, gold hands. 48 mm diameter.
London Patent Chronometer escapement, a development of George Morton's original Patent No 2432, October 1857. As development took place the watches are variously engraved, if at all: Morton's Patent; Mortons Patent Improved; Patent Chronometer; London Patent Chronometer; and finally Patent Union Chronometer, all numbered within the same sequence, the last known number being just over 3000. A second Patent was taken out in 1859. See also Randall The Time Museum Catalogue of Chronometers, items 127 and 128.
NB: The escapement is detached and impulses the balance to one side only, like chronometer escapements, but the impulse is delivered like a lever. Never taken up for the most precise of work, this escapement nevertheless had a long life and, judging by those few examples that survive, usually show an active and long working life.
Dial with faint hair crack at 6, as usual, and a few scratches, and the light engine-turning on the case showing wear, as does the bow. Otherwise complete and original - this rare escapement seem to mostly survive as movements. Cleaned and guaranteed.
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