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Cambridge University Library, MS Add.3970, Printer's Copy of Newton's Opticks, fol 111

Book I, Part II, PROP VI, PROB II.

In a mixture of primary Colours, the quantity and quality of each being given, to know the Colour of the compound.

Fig 11.

With the Center O and Radius OD describe a Circle ADF, and distinguish its circumference into seven parts DE, EF, EG, GA, AB, BC, CD,

proportional to the seven muisical Tones or Intervals of the eight Sounds,

Sol, la, fa, sol, la, mi, fa, sol, contained in an Eight;

that is, proportional to the numbers 1/9, 1/16, 1/10, 1/9, 1/16, 1/16, 1/9.

Let the first part DE represent a red Colour, the second EF orange, the third FG yellow, the fourth GH green, the fifth AB blue, the sixth BC indico, and the seventh CD violet.

And conceive, that these are all the Colours of uncompoumded Light gradually passing into one another, as they do when made by Prisms.

Cambridge University Library, MS Add.3970, Printer's Copy of Newton's Opticks, fol 143v

Book II, Part IV, Obs XIV. But it agrees something better with the Observation to say, that the thicknesses of the Air between the Glasses there,

where the Rings are successively made by the limits of the seven Colours, red, orange, yellow, green, blue, indigo, violet in order,

are to one another as the Cuberoots of the Squares of the eight lengths of a Chord, which found the notes in an eighth, sol, la, fa, sol, la, mi, fa, sol;

that is, as the Cube-roots of the Squares of the Numbers, 1, 8/9, 5/6, 3/4, 2/3, 2/5, 9/16, 1/2.

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Book II, Part IV, Obs XIV. But it agrees something better with the Observation to say, that the thicknesses of the Air between the Glasses there,

where the Rings are successively made by the limits of the seven Colours, red, orange, yellow, green, blue, indigo, violet in order,

are to one another as the Cuberoots of the Squares of the eight lengths of a Chord, which found the notes in an eighth, sol, la, fa, sol, la, mi, fa, sol;

that is, as the Cube-roots of the Squares of the Numbers, 1, 8/9, 5/6, 3/4, 2/3, 2/5, 9/16, 1/2.

α ©