JACOB AUCH, WEIMAR | A VERY RARE GOLD DOUBLE DIALLED ASTRONOMICAL CALENDAR WATCH WITH GEOCENTRIC PLANETARIUMCIRCA 1790

• Movement: gilded full plate with going barrel, cylinder escapement, plain three-arm balance• Dials: first: white enamel, the edge with Arabic numerals for hours running twice from 1-12 in black and 1-12 in pink, four subsidiary dials for minutes, date combined with month, regulation, seconds combined with days of the week, aperture for winding, gold hands, the hour hand with an additional steel support carrying a square for rapid resetting of the calendar • second: light blue enamel geocentric planetarium dial decorated with gold stars and an outer month ring, various lines of the ecliptic zodiac marked in black, with three concentric hands of steel mounted with the earth, a gold sun and moon, the entire dial revolving once per year, the ecliptic line shown by a polished steel band attached to the engraved silver dust ring• Case: plain gold moulded bezels

Time Museum, Rockford, Il, Inventory No. 1698
Sotheby's New York, Masterpieces from the Time Museum Part II, 19 June 2002, lot 53

Peter Friess, Rediscovering Josef Weidenheimer (1758-1795), Antiquarian Horology, June 1999, No. 6 Vol. 24, p. 532, fig. 12

Movement: running at the time of cataloguing. Calendar advancing. Dial: crack to the white dial to the edge at the bottom below the regulator sector. The second light blue dial with chip to the edge between Sept and Oct. Chip to the winding hole and next to the blued screws. Case: indentation to the band by the opening, scuffs throughout.
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. All dimensions in catalogue descriptions are approximate. Condition reports may not specify mechanical replacements or imperfections to the movement, case, dial, pendulum, separate base(s) or dome. Watches in water-resistant cases have been opened to examine movements but no warranties are made that the watches are currently water-resistant. Please note that we do not guarantee the authenticity of any individual component parts, such as wheels, hands, crowns, crystals, screws, bracelets and leather bands, since subsequent repairs and restoration work may have resulted in the replacement of original parts. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue. In particular, please note it is the purchaser's responsibility to comply with any applicable import and export matters, particularly in relation to lots incorporating materials from endangered species.NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING A LOT, ALL LOTS ARE OFFERED AND SOLD AS IS" IN ACCORDANCE WITH THE CONDITIONS OF BUSINESS PRINTED IN THE SALE CATALOGUE."

**Please be advised that bands made of materials derived from endangered or otherwise protected species (i.e. alligator and crocodile) are not sold with the watches and are for display purposes only. We reserve the right to remove these bands prior to shipping."

Jacob Auch, born in 1765, in Echterdingen, Germany, was a student of the famous German watchmaker Philipp Matthäus Hahn. Auch worked in the Atelier until Hahn's death in 1790 after which he opened his own workshop in Vaihingen. In 1798 Auch was appointed watchmaker to the court of Weimar. Auch displayed a talent in mathematics at an early age; at eleven he was known to assist his teachers in the explanation of complicated mathematical problems. In addition to production of complicated astronomical watches he is also known to have made calculators; another skill he would have learnt from Hahn, who was known for his masterful calculations. Lorenz Julius Böckmann, head of the Physical Institute in Karlsruhe from 1764-1798, wrote an essay about Auch in 1790 and said that Auch could be considered one of the leaders in the development of the calculator. He noted that Auch's calculators were more precise, easier to use and more affordable.

For examples of Auch's Astronomical watches, see: Beyer Museum, Zurich; Württembergishches Landesmuseum, Stuttgart and Antiquorum Geneva, 14 October 1990, lot 394. For an illustration of the Auch in the Beyer Museum see Uhrenmuseum Beyer Zurich, Antike Uhren, pp. 84 & 85, Cat. No. 36 and the back cover. For a discussion of Jacob Auch and his work see, Alte Uhren, No.6, 1987, "Jacob Auch-ein Schüler von Philipp Matthäus Hahn."

For further information on other similar astronomical watches by Auch, see the exhibition catalogue, Ausstellungs Katalog Philipp Matthäus Hahn 1739-1790, Stuttgart, 1989, Table 22, and pp. 509-513.