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Webster 1913 Edition
Tachometer
Ta-chom′e-ter
,Noun.
[Gr.
τάχοσ
swiftness, speed (fr. ταχύσ
quick) + -meter
: cf. F. tachomètre
.] An instrument for measuring the velocity, or indicating changes in the velocity, of a moving body or substance.
Specifically: –(a)
An instrument for measuring the velocity of running water in a river or canal, consisting of a wheel with inclined vanes, which is turned by the current. The rotations of the wheel are recorded by clockwork.
(b)
An instrument for showing at any moment the speed of a revolving shaft, consisting of a delicate revolving conical pendulum which is driven by the shaft, and the action of which by change of speed moves a pointer which indicates the speed on a graduated dial.
(c)
(Physiol.)
An instrument for measuring the velocity of the blood; a haematachometer.