CONCORD AUTOMATIC CHRONOGRAPH 3 Instruction Manual page 42

TACHYMETER
Scale used to measure speed in
km/h. Start the chronograph, walk
or run exactly 1 km from your point of
departure.
Look at the dial of your watch, the
seconds-hand uses the «tachymeter
scale» to indicate your speed in km/h
for the kilometer you just travelled.
AUTOMATIC CHRONOGRAPH 2 42