Short Risalah 2 - C.O.S.C.

C.O.S.C. - contrôle officiel suisse des chronometres
The C.O.S.C. is a non-profit association. It was created by five watchmaking cantons (Bern, Geneva, Neuchatel, Solothurn and Vaud) as well as the Federation of the Swiss Watch Industry in 1973. It encompasses the laboratories that had been established independently of each other from the late 19th century onwards.
A chronometer is a timekeeper precise enough to be used as a portable time standard, usually in order to determine longitude by means of celestial navigation. In the world of watches, the term is also attached to those tested and certified to meet certain precision standards. In Switzerland, only timepieces certified by the C.O.S.C. can use the word "Chronometer" on them.

C.O.S.C. measurement methods:
Only the movement is tested and the tests bear absolutely no relation to a simulation of watch behaviour and performance when worn.
The test is divided into 16 days, 24-hour periods. The watch is tested in 5 positions and at 3 temperatures.