Find the tachymeter scale on the watch bezel or dial
Start the chronograph at the beginning of a measured distance or timed event
Stop the chronograph when the distance is completed or the event ends
Read the chronograph seconds hand position on the tachymeter scale
Use the scale to determine the speed or rate per hour
If the hand stopped at 60, the speed is 60 units per hour
If the hand stopped at 120, the speed is 120 units per hour
Use it only for events measured over a known distance or fixed interval
Reset the chronograph after reading the result