TachymeterSkala

A tachymeter scale, often found on the bezel or dial of a watch, is a speed-measuring tool. It allows the wearer to calculate average speed over a fixed distance, typically one kilometer or one mile, using the chronograph function of the watch. The scale is calibrated to display speed in units per hour.

To use a tachymeter, one must first start the chronograph precisely as they begin measuring the distance. When the distance is completed, the chronograph is stopped. The number on the tachymeter scale that aligns with the second hand indicates the average speed. For example, if the second hand stops at the '60' mark, the average speed was 60 units per hour. If it stops at the '120' mark, the average speed was 120 units per hour. This is because the scale is inversely proportional to time. Shorter time intervals correspond to higher speeds.

The tachymeter scale is particularly useful for timing events where a consistent distance is covered, such as a lap on a race track, a specific stretch of road, or even the speed of a runner. It relies on the accuracy of the chronograph's timing mechanism and the precise measurement of the distance. The markings on a tachymeter scale are typically logarithmic, allowing for a range of speeds to be displayed. The effectiveness of a tachymeter is limited by the accuracy of the stopwatch and the range of speeds it can meaningfully represent.