Fine free-sprung movement with very rare differential up/down, circa 1890.
Three-quarter plate keyless (openface set) movement with resting-barrel, jewelled to the centre with cap jewels on balance (diamond), lever and escape, the 16-size pillar-plate stamped JP (Joseph Preston). Top quality double-roller detached lever escapement. Compensation balance, free-sprung balance-spring with overcoil. Signed enamel dial with sunk seconds and state-of-wind indication at 12. 46 mm diameter, 9.5 mm deep, not including centre arbor.
Lewis Donne, member of the Clockmakers' Company, died 1918 aged 78, retailer. NB: The actual makers may be Usher & Cole - see a complete watch of this rare caliper retailed by A H Hickman in the Archive section of my website. It was this type of differential work that Anthony Randall describes as the inspiration for his invention of the double-axis tourbillion.
Joseph Preston, Prescot, the most famous of Lancashire watch rough movement manufacturers, supplier to all the best English finishers and retailers of his day. This movement is rare in having the centre wheel placed 'above' the balance, in continental style, done to allow the differential arbor to run between the plates - see pics from an exactly similar movement: the arbor is just 7.5 mm long, and note the extra steel pivot in the top plate, opposite from the 3rd and 4th wheels and their jewelling. NB: Up/down work is much harder to achieve in watches with a going-barrel rather than the normal English fusee, thus the extra complication.
Lacking hands, and part of the stop-work. Otherwise a very good example of this rare caliper, with differential work intact and an almost perfect enamel dial - just a very small chip at the seconds hole and at the edge. Not cleaned by me but will tick happily when wound.
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