Hughes
The difference in the development of a major and a minor harmony
—The twelve developing keys mingled
—D? shown to be an imperfect minor harmony
—E? taking B? as C? to be the same as D#
—The intermediate tones of the seven white notes are coloured, showing gradual modulation
—As in the diagram of the majors, the secondaries are written in musical clef below the primaries, each minor primary sounding the secondaries of the third harmony below, but in a different order, and one tone rising higher, . . . . . 34 [Harmonies of Tones and Colours, Table of Contents3 - Harmonies]

This diagram shews the two last minor primaries of a series of 12, with the 12 of a higher series, and the two first of a series higher still. As in the diagram of the Major, the secondaries are written below the primaries, and the sharps or flats of each harmony are written to their respective notes. With the exception that one of the primaries rises a tone higher, it will be observed that in the same way the notes of each minor primary are identical with the secondaries of each third harmony below, but in a different order; and the double tones are altered sharp or flat, as before. [Harmonies of Tones and Colours, Diagram Shews the Two Last Primaries, page 34e]