books an instrument for measuring rotation and frequency
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# A tool for measuring or plotting angles
# gas pressure gauge
# Chronograph
# Compressor
# photometer
# protractor
# digital frequency measurement circuit
# atmospheric pressure measuring instrument
# height measuring tool
# The relationship between wavelength and frequency
# Reason and frequency
# Speed, wavelength and frequency
# Selection of amplitude and frequency
# Ruling and instrument in the era of Muhammad Ali
# financial instrument
# musical instrument arts
# The military instrument of foreign policy
# optical instrument
# surgical instrument
# percussion instrument
