Abstract: A tachymeter device for indicating an average speed of a moving object and a wristwatch comprising such a tachymeter device comprising a timer and an activator for manually starting the timer when the object passes a starting mark and for stopping the timer when the object passes a defined distance from the starting mark. The tachymeter device may further comprise a housing, a scale for indicating an average speed of the moving object, and a pointer for indicating a measured average speed on the scale. The scale may be designed as a scale part that is arranged detachably at the housing. The scale part may be selected from a set of scale parts comprising differing scale parts each having a scale with speed indication for indicating speed ranges corresponding to differing pre-defined distances.

Abstract: A tachymeter device for indicating an average speed of a moving object and a wristwatch comprising such a tachymeter device comprise a timer and an activator for manually starting the timer, when the object passes a starting mark, and stopping the timer, when the object passes a defined distance from the starting mark. They further comprise a housing, a scale for indicating an average speed of the moving object and a pointer for indicating a measured average speed on the scale, wherein the measured average speed is derived from said defined distance and a time to cover said defined distance measured by the timer. The scale is designed as a scale part that is arranged detachably at the housing. The scale part is selected from a set of scales parts comprising a plurality of differing scale parts each having a scale with speed indication for indicating speed ranges corresponding to differing pre-defined distances.