Display for visual matching of musical harmonics - has two concentric and superimposed discs turning to expose information through openings in masks

摘要

The display comprises two circular and superimposed discs, these are mounted concentric on a common axis. Each disc is divided into 36 sectors by radial lines and the lower disc has the twelve chromatic scales marked on it. Each scale is repeated three times consecutively. The upper disc is transparent and is marked with details of the various musical pitches on an intermediate ring. The centre part of this disc is an opaque black mask with openings to permit only the notes of the various pitches sought to appear.