H[ae]matachometer

from The Collaborative International Dictionary of English v.0.48

Haematachometer \H[ae]m`a*ta*chom"e*ter\
   (-t[.a]*k[o^]m"[-e]*t[~e]r), n. [H[ae]ma- + Gr. tachy`s swift
   + -meter.] (Physiol.)
   A form of apparatus (somewhat different from the
   hemadrometer) for measuring the velocity of the blood.
   [1913 Webster]