18th, 20th, and 24th, I first explain the more compounded. And first to
shew how the Colours in the fourth and eighteenth Observations are
produced, let there be taken in any Right Line from the Point Y, [in
_Fig._ 6.] the Lengths YA, YB, YC, YD, YE, YF, YG, YH, in proportion to
one another, as the Cube-Roots of the Squares of the Numbers, 1/2, 9/16,
3/5, 2/3, 3/4, 5/6, 8/9, 1, whereby the Lengths of a Musical Chord to

4th, 9th, 12th, 18th, 20th, and 24th, I first explain the more compounded. And first to shew how the Colours in the fourth and eighteenth Observations are produced, let there be taken in any Right Line from the Point Y, [in _Fig._ 6.] the Lengths YA, YB, YC, YD, YE, YF, YG, YH, in proportion to one another, as the Cube-Roots of the Squares of the Numbers, 1/2, 9/16, 3/5, 2/3, 3/4, 5/6, 8/9, 1, whereby the Lengths of a Musical Chord to sound all the Notes in an eighth are represented; that is, in the...