Extremely rare and well-preserved fine ZENITH observatory chronometer prototype Cal. 135 created in testing department early 1950s. As almost any other prototype it has no serial number, so it never used for actual competitions, however Zenith heritage department has confirmed by phone, that they were testing such Cal. 135 chronometer with Glucydur balance at 18.000 alt/hour to try to achieve better results. Very unusual configuration with modified regulator and oversized Glucydur balance makes this timepiece virtually unique and very important.
Case: three body, gold plated, circular case, polished bezel, with glazed transparent display back, large crown. Dial: silvered matte dial with outer minute track, Arabic numerals, blued dauphine hour/minute hands, and baton seconds hand, engine-turned subsidiary seconds. Movement: gold plated Cal. ZENITH 135, frequency 18’000 bpm, oversized Glucydur balance. Movement and dial signed, Diam. 36 mm;
Ephrem Jobin was the brains and hands behind the Zenith Calibre 135. Introduced in 1948 at the height of a battle to achieve increased precision fought among several watch manufacturers in the Observatory competitions, Caliber 135 included several innovative technical features that enabled it to win numerous prestigious awards and prizes, including an unprecedented 5 consecutive Neuchâtel Observatory chronometry prizes from 1950 to 1954. In all, the movement garnered about 200 honors, two-thirds of which were first prizes.
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.
Watch is in overall very good condition 8/10.