Tachymeter scale
Tachymeter scale
A feature found on some chronograph watches, measures the speed at which the wearer has traveled over a measured distance. In watchmaking, a timer or chronograph with a graduated dial on which speed can be read off in kilometres per hour or some other unit.
For events that happen either very quickly or slowly, one needs to adjust the sixty-second tachymeter scale commonly found on watches. The scale on a watch is only valid for things that happen in 60 seconds or fewer, and the scale is also difficult to resolve for events that take fewer than 10 seconds or so to occur. As an example, if it takes 100 seconds to eat an apple, cutting that number in half allows one to say that it takes 50 seconds to eat half an apple. Using the tachymeter scale one can calculate that 72 half apples (36 whole apples) could be eaten in one hour.