Tachometer?
Tachymeter, instrument for measuring speed over a measured distance. Also called a Tachymeter. Time an event that takes less than 1 minute. The scale on the Tachometer will tell you how many of those events will occur in 1 hour. e.g. A racing car covers 1 mile in 30 seconds. The sweep seconds hand, when stopped at the end of the mile, would point to 120 on the tachometer. The average speed of the car is 120 m.p.h.
