English gold cylinder watch with centre seconds Circa 1780

Gold open faced pocket watch
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A fine and rare English 18K gold pocket watch with cylinder escapement, centre seconds and stop feature, circa 1780. The back with gold shutter for the winding aperture. Gilt dust cap with bayonet fixing to the movement. White enamel dial, radial Roman numerals, outer minutes-seconds divisions with five-minutes-seconds Arabic numerals. Gold beetle and poker hands.

A hinged, frosted gilt full-plate movement with cylindrical pillars, fusee and chain, Harrison’s maintaining power, fully jewelled cylinder escapement with large brass escape wheel, steel balance with flat balance spring, single-footed cock finely decorated with a profile bust, military trophy and foliate scrolls, large diamond endstone, silver regulation dial, stop feature with a lever at 9 o’clock. Signed on the movement and dust cap.
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Diameter: 55 mm
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Signed: Brockbank  London
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Brockbank John and Myles Brockbank, brothers who traded at 6 Cowper’s Court, were pioneers in chronometer making. Myles was admitted to the Clockmaker’s Company in 1776 and John in 1779. Earnshaw claimed that he showed them his version of the spring detent escapement and that they passed on the information to Arnold. One of their workmen, Peto, invented the cross-detent escapement, combining the theoretical advantages of Arnold’s and Earnshaw’s escapements; several examples by the Brockbanks survive, coupled with an over banking device which limits the expansion of the helical spring. After Myles death in 1821, the brothers were succeeded nephews, also named John and Myles, who traded as John Brockbanks & Company. From 1815 to 1835 the firm was called “Brockbank & Atkins”, still at 6 Cowper’s Court.