English rare observatory watch with chronograph Circa 1890

Open faced silver pocket watch by Smith & Son
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An English very rare observatory watch with split-seconds chronograph and 60 minute register, circa 1890.
Solid silver case with case number 216055; lever escapement and signed on bridge “Smith & Son London 141-166“; original white enamel dial “numbered 141-166” with three sunk subsidiary dials for time indication, 60min counter on the left and subsidiary seconds on the right, split-seconds chronograph and blued steel hands.
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Diameter: 54 mm
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Weight: 138 g
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Signed: Smith & Son London 141-166