{ } [ Gr. &unr_; beautiful + &unr_; appearance, form + &unr_; sound. ] (Physics.) An instrument invented by Professor Wheatstone, consisting of a reflecting knob at the end of a vibrating rod or thin plate, for making visible, in the motion of a point of light reflected from the knob, the paths or curves corresponding with the musical notes produced by the vibrations. [ 1913 Webster ]