Four piece slide-rule for musical analysis - has three movable calibrated plates with relative positions giving visual indication of scale, note interval etc.

摘要

This slide rule instrument is used to display the melodic and harmonic content of music. It consists of a rigid transparent cassette in which three movable calibrated plates are inserted. Each plate represents one of the qualities of a musical note. The three variables are scale system, note and interval. The lowest of the three plates (5) can be moved from side-to-side in the cassette, as can the highest plate (4). The middle plate (6) can be moved in any direction. The instrument is intended as a teaching aid to help students improvise, analyse and compose music.