Danish silver astronomical keyless deck watch Circa 1910

Silver deck watch by Elis Strömgren – Jens Olsen / Cornelius Knudsen
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A very rare Danish, navigator deck watch, so-called combined sidereal and meantime watch, circa 1910. Developed for astronomical navigation at sea.
Silver, polished case. Signed enamel dial with radial Arabic 24 hours on a subsidiary dial at three, radial Roman hours on a subsidiary dial at nine, outer radial Arabic minutes, subsidiary dial for auxiliary seconds, continuous 24-hour sidereal time as well as a chosen time zone or Greenwich time,  two spade hands, single Breguet hand and a single hand with sun pointer. Frosted, gilt precision bridge movement with wolf teeth winding wheels, screw compensation balance, and index spring fine adjusting device.
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Diameter: 60 mm
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Weight: 177 g
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Signed: Strömgren og Olsen, Cornelius Knudsen, Kobenhavn
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Sidereal time is the time it takes the earth to make one full revolution around its axis. Since it is based on the Earth’s rotation relative to the fixed stars, it is called sidereal or star time (sider = star in Latin). The sidereal day has 23 hours, 56 minutes, and 41 seconds.