23. April 2020

Tachymeter , tachymeter scale (also: tachometer, tachometer scale) Clock function / scale for measuring speeds. The tachymeter uses the reciprocal proportional relationship between time and speed to measure the (average) speed if the distance (= reference / base) is known . The ring scale shows speeds for different time periods. If, for example, the second hand of a chronograph is started when a milestone is passed by car , the speed can be read on the tachymeter scale when the next milestone...