Combination of discs synthesizing the musical harmonic theory applied to the piano and the guitar (Machine-translation by Google Translate, not legally binding)

摘要

A combination of discs synthesizing the musical harmonic theory applied to the piano and the guitar, essentially characterized by the superposition of five discs of different sizes, held in the center by an axis on which they can rotate indistinctly and containing printed drawings, legends, numerations and signs, and some open windows through which the annotations made on the immediate disks can be read. (Machine-translation by Google Translate, not legally binding)