English heavy dust proof expedition deck watch Circa 1893

Historical open faced deck watch by Herbert Blockley
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An English historical interesting, fine and heavy dustproof expedition deck watch private property of the polar explorer Frederick George Jackson, circa 1893.
Solid silver case, polished, with engraving The Jackson Harmsworth Polar Expedition and monogram FGJ on screw back, case maker’s punch mark PW, screw bezel and winding crown underneath screw protective cap secured by a chain, and leather sealing rings. Signed enamel dial with radial Roman numerals, auxiliary seconds, 30-hour power reserve indicator, and blued spade hands. Frosted, gilt 2/3 plate movement with chain/fusee, English lever escapement, large gold screw chronometer balance, free-sprung balance spring, florally engraved balance cock, diamonds endstone on balance, chatoned ruby end stones on the lever and escape wheel.
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Diameter: 59 mm
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Weight: 220 g
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Signed: Herbert Blockley, London