5. Special applications

The main distinctions are :

• single-race measurements, determined by an initial and a final instant (time of a competitor in an event, measurement of a period);

• cumulative measurements, comparing the steps of two clocks over as long a period as is necessary for measurement accuracy.

Each device includes a time counter (pointer and dial, tape recorder), and manual or automatic tripping and stopping devices: the result is two sources of error that must be balanced and adapted to the phenomenon under study.