THOMAS MERCER NO 21801, MARINE CHRONOMETER, WITH DETENT ESCAPEMENT, ENGLAND CIRCA 1920 the mechanism, mounted on cardan joints, is enclosed in a mahogany casket-shaped case, at the top a smooth glass allows the hours to be read off; silvered metal dial signed Thomas Mercer, blue steel hour and minute hands, power reserve dial at 12 o'clock, seconds dial at six o'clock. The front label reads: SUPPLIED BY WATCHES OF SWITZERLAND LTD 34.36 BEECH ST LONDON E.C.T. No. 21801 Movement with Detent escapement, conoid, two-day power reserve. H. 17 cm, W. 18.5 cm, D. 19.5 cm THOMAS MERCER MARINE CHRONOMETER WITH DETENT ESCAPEMENT, ENGLAND CIRCA 1920