Diatonic scale are major scales (those with a major third/triad: Ionian, Lydian, and Mixolydian), three are minor (those with a minor third/triad: Dorian, Phrygian, and Aeolian). To these may be added the seventh diatonic scale, with a diminished fifth above the reference note, the Locrian scale. These could be transposed not only to include one flat in the signature (as described by Glarean), but to all twelve notes of the chromatic scale, resulting in a total of eighty-four diatonic scales. The modern musical keyboard originated as a diatonic keyboard with only white keys. The black keys were progressively added for several purposes:
Von Luschan's chromatic scale of the skin type of individuals introduced in 1975 by Harvard dermatologist Thomas B. Fitzpatrick to describe sun tanning behavior. The von Luschan scale was used extensively throughout the first half of the 20th century in race studies and anthropometry. However, the results were inconsistent: in many instances, different investigators would give different readings of the same person. The von Luschan scale was largely abandoned by the early 1950s, replaced with methods utilizing reflectance spectrophotometry. The following table shows the 36 categories of the von Luschan scale in relation to the six categories of the Fitzpatrick scale: Von Luschan's chromatic