Swiss 18 Carat gold deck watch with Sidereal time mean time Circa 1918

Deck watch based on the Strömgren og Olsen patent
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An absolute rarity this only known piece of the Strömgren og Olsen Sidereal time/mean time deck watch with gold case, made by Alexander Hüning in Genève, Switzerland, circa 1918. The open faced plain case of this watch was crafted from 18 Carat gold. The white enamel numbered dial is inscribed with Patent Strömgren og Olsen and shows the mean solar time and the sidereal time and seconds in a subsidiary dial at six o’clock. The caliber Alex Hüning Geneva movement has an anker chronometer escapement, a large bi metallic chronometer balance, a swan neck fine regulation, a splitted barrel bridge, wolf’s toothing and a separate plate for the sidereal time.
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Diameter: 60 mm
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Weight: 188 g
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Signed: No name
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To date, only a few examples of these type of watches with silver cases are known and only this one example here in gold. The gold case is matching the known silver cases in all technical details. A detailed report on these watches can be found in Klassik-Uhren 1/1995. These watches rarely appear at auction. Number 0541 achieved a record result of almost CHF 50.000 in Geneva. The exceptional watchmakers Elis Strömgren Svante and Jens Olsen received the Danish patent with the number 22822 on the 11^th of  February 1918 for their invention. They commissioned the manufacture of the watches from the Geneva chronometer manufactory Alexander Hüning, and Hüning’s manufactory punch (“FH or AH”) can be found on some of the watches. On some watches there are also the movement numbers under the dial or on the case, most with 54900′ numbers, made circa 1914-1918.
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A sidereal day is the length of time it takes the earth to make one complete revolution around its axis. Compared to the commonly used solar time, which is based on the revolution of the earth by the sun, the sidereal day is almost four minutes shorter than the solar day.
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The watch comes with a copy of the original instruction manual by Cornelius Knudsen, Royal Court Instrument Maker of the Nautical Department Copenhagen!
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Alexander Hüning
Alexander Hüning was born in 1855 and died in 1931. He was most likely a native of Germany who went to Geneva around 1880 after completing his apprenticeship. Alexander became a citizen of Geneva in 1898. In 1893 Hüning and Emile Fiebiger established the company Fiebiger & Hüning at the Rue de Lévrier 13 in Geneva together, which Hüning continued on his own after Fiebiger’s death. He was particularly known for his fine, complicated pocket watches of supreme quality. An overview of Hüning’s life and his work is available in Klaus Pöhlmann’s “Alexander Hüning, ein Deutscher Uhrmacher in der Schweiz” (a German watchmaker in Switzerland).