Telemeter is a type of chronograph watch that is used to measure the distance of an event based on the time elapsed between two visual cues. It typically consists of two scales—a tachymeter scale and a telemeter scale—that are marked around the circumference of the watch’s dial. The tachymeter is used to measure speed, while the telemeter is used to measure the distance of events that can be heard or seen, such as lightning or artillery fire. The user determines the distance of the event by starting the chronograph when the event is heard or seen, and then stopping it when the same event is heard again. The distance is then read from the telemeter scale.
