cycloscope

From cyclo- +‎ -scope.

cycloscope (plural cycloscopes)

1. A machine for measuring the velocity of rotation, as of a wheel of a steam engine.

• Edward H[enry] Knight (1877) “Cycloscope”, in Knight’s American Mechanical Dictionary. […], volumes I (A–GAS), New York, N.Y.: Hurd and Houghton […], →OCLC.
• “cycloscope”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.