Stream clock

1.(Physiol.) An instrument for ascertaining the velocity of the blood in a vessel.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
During the highest tides of the month--the so-called spring tides that occur when the moon is full or new--the ice stream clocked in at a velocity of 1.15 m/day.