Reaction- Time.
45
of a locomotive is not so conducive to a quick jump by
the passengers on the platform as a sudden escape of
steam.
A particular case of reaction to sound is found in start¬
ing a race. In short-distance, or sprint, racing the time
required for the re¬
action is a very im¬
portant factor. The
starter’s pistol is
fired and the racers
are off, but the man
with a very short
reaction-time will
have gained a re¬
spectable fraction of Fig',7' The pistoUkey'
a second over the other. To measure this reaction-time
an electric contact is put on the end of the starter’s pistol.
The arrangement is shown in Fig. 17. The firing of the
_pistol causes
Fig. 18. The Runner’s Key.
cC the wing to fly
back and break an
electric circuit, thus
making a record. A
runner’s key of the
kind shown in Fig. 18
is attached to the run¬
ner by a thread. The
start of the runnef jerks and breaks the thread ; this
moves the lever and makes another record.
Although I have never had time to carry out an ex¬
tended series of èxperiments on racers, the experi¬
ments made have shown a few facts. The first point
noticeable is that long-distance runners are very much
Reaction-time
at the start of a
race.
Some results.