[The] experiments of Professor J. D. Forbes, which I witnessed in 1849… [established] that blue and yellow do not make green, but a pinkish tint, when neither prevails in the combination…[and the] result of mixing yellow and blue was, I believe, not previously known.—James Clerk Maxwell, Experiments on colour, as perceived by the eye, with remarks on colour-blindness (1855), Transactions of the Royal Society of Edinburgh
Initially, he compared the color he observed on the spinning top with a paper of different color, in order to find a match. Later, he mounted a pair of papers, snow white (SW) and ivory black (Bk), in an inner circle, thereby creating shades of gray. By adjusting the ratio of primaries, he matched the observed gray of the inner wheel, for example:
To determine the chromaticity of an arbitrary color, he replaced one of the primaries with a sample of the test color and adjusted the ratios until he found a match. For pale chrome (PC) he found . Next, he rearranged the equation to express the test color (PC, in this example) in terms of the primaries.
- ↑ Peter Michael Harman (1998). The Natural Philosophy of James Clerk Maxwell, Cambridge University Press.
- ↑ James Clerk Maxwell (2003). The Scientific Papers of James Clerk Maxwell, Dover Publications.
- ↑ James Clerk Maxwell (1855), Experiments on colour as perceived by the eye, with remarks on colour-blindness