COSC is a non-profit Swiss testing institute, Contrôle Officiel Suisse des Chronomètres, which tests movements for precision. The test protocol is performed on uncased movements, which have to have a seconds hand and a serial number. Movements are individually tested over the course of 16 consecutive days, in five positions, at three different temperatures and…
This German standard is similar to ISO 3159 that forms the basis for COSC certification. Watches are tested for compliance with DIN 8319 at Glashütte Observatory. The DIN 8319 procedure requires 15 days of testing, in the same positions as for COSC (dial up, dial down, crown left, crown on top, crown below), with an…
This is at the very heart of it all. It was Galileo Galilei who first noticed it, in a cathedral in Florence. He watched a chandelier swinging, propelled by the draughts, and saw that it seemed to be going much faster when the swings were wider. So he timed them, counting probably ten or twenty…
To my admittedly devious mind, the “positions” specified in watch adjustment conjure up an image of a plush, dimly-lit room somewhere in a watch factory where couples of workers are checking the correct functioning of watches while engaged in a variety of Kama Sutra positions. Alas, the reality is much less colourful. A watch adjusted…
If you ask advice from a collector about a watch as investment, he or she will invariably say: buy a watch because you like it. If you want to have something precious and see its value go up over the years, buy a bar of gold. But even a collector likes to be able to…
The great divide in chronographs is between cam chronograph movements, in which the pushers rotate a cam (or coulisse) which in turn moves a series of levers, and column wheel chronographs, in which the pushers rotate the column wheel which then operates the levers. The column wheel provides smoother pusher operation and is the higher-end…
Water resistance ratings as they are published and indicated on watches are very misleading. Most watches are rated at 3 bar, or 3 atmospheres, corresponding to 30 metres water resistance. So you may think, wow, 30 metres depth! No problem about taking my watch when I go swimming, or keeping it on in the shower…
Rate symmetry is involved with the regulation of a mechanical watch. It is connected to the fact that every cycle of the balance wheel consists of two swings, first in one direction and then in another. At every swing, the impulse pin on the balance roller shifts the pallets across, from one side to the…