Traditional Jewish system of measuring the time

Konstantin Chaykin’s interest in the traditional Jewish system of measuring the time was piqued by the high accuracy embedded in it. According to this system, an hour is divided into 1080 parts known as heleks, and each helek consists of 76 moments, known as regaim (singular: rega), equivalent to about 0.044 seconds. The difference between the length of the lunar month as determined by astronomical methods and that in heleks, calculated as 765,433 heleks, is only 0.136 heleks, or 0.45 seconds, giving a very high degree of accuracy for the indication of the moon phase – 0.9999998.

The hour markers on the dial of the “Decalogue” watch collection are made in the form of letters of the Hebrew alphabet. Guided by the fact that Hebrew text is read from right to left, Konstantin Chaykin decided to modify the drive for the hands, so the hands rotate in the opposite direction. This idea was inspired by one of the tourist attractions of Prague in the Czech Republic, the Jewish Town Hall clock, made by the Prague clockmaker Sebastian Laudensberger in 1764, which became famous for the fact that its hands turn in the opposite direction.

In watchmaking tradition the moonphase indicator has a secondary, subordinate status. For the “Decalogue” watch Konstantin Chaykin created an unusual and memorable design, where the main elements – the dial with hour and minute hands and the moonphase indicator – are roughly equivalent. The moonphase indicator is inverted from its classical position, meaning the semi-circular window looks like a smile. The “Decalogue” watch was later chosen by Konstantin Chaykin as one of the prototypes for the “Joker” watch.