Unique record-breaking watches
The Sauterelle a lune perpetuelle has the most precise phase of the moon indication ever built in a wristwatch. For a precise phase of the moon, watchmakers need to represent the ratio of 1: 29.530588 by the ratio of teeth on the respective gear wheels. This has proved rather complicated for watchmakers and involves using fractions to work out the number of teeth. Andreas Strehler solved this problem by driving the moon disc continuously instead of switching it forward once a day. By a clever combination of external and internal toothing and by the use of prime numbers for the numbers of teeth on these gear wheels, Andreas Strehler could represent complex fractions.