French antimagnetic deck watch of the British Navy Circa 1910

Silver open faced pocket deck watch by L. LeRoy & Cie.
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A rare French antimagnetic deck watch “Ecran Paramagnètique Breveté” of the British Royal Navy, circa 1910.
Wooden box with numbered ivory shield. Silver polished case with inner antimagnetic protective soft iron inner case. Signed enamel dial with radial Roman numerals, sunk subsidiary dial for the seconds and blued spade hands. Bridge movement, frosted, gilt, signed, with “broad arrow”, wolfteeth winding wheels and Guillaume gold screw compensation balance.
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Diameter: 58 mm
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Weight: 154 g
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Signed: L. LeRoy & Cie