Extremely rare and well-preserved fine LONGINES Observatory Competition chronometer SN. 6940786, Cal. 15.68z (Breguet overcoil hairspring, Guillaume gold screw compensation balance beating at 18000 bph), with its original testing wooden housing. Steel case size is 40mm. Made in 1947 as a hunter pocket chronometer, was chosen for Observatory Competitions and submitted for the first competition in 1949 to the Geneva Observatory, where achieved quite a good results, thanks to Longines precision timer “regleur” Robert Chopard, who spent months of fine adjustments. More information about this amazing movement you could find in the great article, written by Tony C. on Omega forum.
Competition chronometer-quality wristwatch movements are not “ordinary” C.O.S.C. certified movements. These movements were designed and finished to excel in the rigorous world of Observatory Competitions, as conducted in Geneve and Neuchatel in the years 1944 through 1967.
Unfortunately the certificates “Bulletin de Marche” are no longer available from the observatories – but A. Hidding copied a lot of their records, so you can order a copy of the information from his website. Based on information provided in these records this chronometer was used for 5! competitions in the “Concours C” over 10 years in 1949, 1950, 1957, 1958, 1959 in the Observatory of Geneva. Thanks to Andreas (@school_watches_swiss) here are detailed information about this particular chronometer results:
- 1949: place 11 of 17 with 637 points;
- 1950: place 16 of 19 with 645 points;
- 1957: place 3 of 13 with 47,6 points (new Reglement);
- 1958: place 8 of 9 with 46,61 points;
- 1959: place 13 of 17 with 43,03 points;
Case: three-body stainless steel glazed case, transparent back. Dial: mate silvered with Arabic numerals, black minutes track auxiliary seconds, blued steel baton hands. Movement: cal. 15,68z, nickel-plated, Guillaume gold screw compensation balance, blued Breguet overcoil hairspring, 18000 bph, movement diameter 34mm. Dial and movement signed.
Up until 1967, the exact length of a second was determined by the Earth’s motion around the sun, and the Neuchatel observatory’s precise optics allowed the fine measurements necessary for precise timesetting to be made. Because of this, Neuchatel began to host observatory chronometer trials – a series of the most stringent, thorough accuracy tests in the history of mechanical watchmaking. The trials, held over a period of forty-five days, encompassed ten separate movement timekeeping tests in five different positions and two temperatures. These observatory trials quickly outgrew their roots as a simple certification test, and before long the trials at Neuchatel were a competitive battleground for the finest watchmakers in Europe. Names like Longines, Zenith, Peseux, Omega and many more traded records for decades, fighting to produce the most accurate movement possible. These movements were never intended for regular use, and bore little to no resemblance to what these companies offered their consumers. Along with the technical prowess of the watchmakers building the movements, in the “racing team” there were specialists, the “regleurs de precision”, who worked tweaking a number of movements until they could find a few of them to bring to the Observatory Competitions. By means of fine adjustments, replacement of key parts, use of special lubricants, they could create a few movements for the Competitions. And often they were the same movements for many years.
Watch is in overall great condition, running and ready to use!