336 Blue
378 Indigo
420 Violet
462 Red
The second and fourth octaves would be heat and actinic rays, and are invisible to our present perception.
The seventh sense is that of spiritual sound; and, since the vibrations of the sixth progress by steps of 6 × 7, those of the seventh progress by steps of 7 × 7. This is their table:
—— Fa ... Green Sound (start of First semi-octave)
49 Sol ... Blue
98 La ... Indigo
147 Si ... Violet