Tachymeter

A Tachymeter scale is a feature found on some wrist watches, typically chronographs, that allows the wearer to measure speed or distance based on time elapsed. It is usually marked on the outer rim of the watch face and is used in conjunction with the chronograph function. To use the tachymeter, the wearer starts the chronograph when a known distance is covered and stops it when the desired speed is achieved. The elapsed time can then be read from the chronograph seconds hand, and the corresponding speed or distance can be read from the tachymeter scale. Tachymeters are often used in sports and racing applications, where quick and accurate measurement of speed is important. They are also popular with car and motorcycle enthusiasts, as well as pilots and navigators.