Paul Ditisheim à La Chaux de Fonds, No 20312, specially made for Mr. Leon Shuster à Paris in 1900.\n\nHighly important 18 ct. gold moon phase astronomical keyless pocket chronometer with perpetual calendar, equation of time and sunrise/sunset indication. This piece was tested from 1901 to 1903 at the Observatory, and was used in an attempt to determine precisely the Longitude of Paris and Neuchâtel in 1902/1903. Awarded the first prize for dock chronometers at the Neuchâtel Observatory contest. Four body massive "Empire" case with deeply reeded band the back engine tumed with a sun burst pattern emanating from a plain oval cartouche. Several Prize Awards engraved inside the back. Gold cuvette engraved by Ditisheim with the complete history of the watch (see above). White enamel 9 piece dial with Arabic numerals, outer minute ring and additional sector for the equation of time centered on 12 o'clock. Subsidiary rings at 9 and 3 o'clock indicating the time of sunrise and sunset in hours and minutes with inner discs for days of the week and the date respectively. At 12 o'clock months for the leap year cycle and subsidiary seconds with inner moon phase aperture below. Blued steel Breguet hands with engraved gold "sun" hand for the equation of time. Frosted gilt brass three quarter plate 21" movement, 21 jewels in the going train, high grade straight line lever escapement, brass-invar Guillaume balance, blued steel balance spring with a Philip' s terminal curve. Astronomical and calendar work adjusted by two olivetted push pieces on the band. Signed on the dial, the case, the cuvette and the movement. In excellent condition. Diam. 61 mm. This watch must certainly be the one described in: Chronomètres et Montres d'Art construits par les ateliers Paul Ditisheim à La Chaux de Fonds (Exposition Nationale - Suisse - 1914) and illustrated on the Frontispice as the most complicated piece ever made by the firm. The uniqueness of this watch is confirmed by the inclusion on the dial of the Neuchâted Prize Awarded and the Meridian of Paris. According to the catalogue, it was also their most expensive complicated watch and sold for Sfr. 5'200 at the time.