What is a tachymeter?
an instrument designed to measure angles and distances
device designed to measure the speed of vehicle movement
device for measuring the acceleration of heart rate
an instrument measuring the speed of rotation of the drive shaft in the engine
A tachymeter or tacheometer is a type of theodolite used for rapid measurements and determines, electronically or electro-optically, the distance to target. The principles of action are similar to those of rangefinders.