Newton's sketch of his crucial experiment (experimentum crucis) in which light from the sun is refracted through a prism. One color is then refracted through a second prism to show that it undergoes no further change. Light is then shown to be composed of the colors refracted in the second prisms.
Image reproduced by permission of the Warden and Fellows,
New College, Oxford
John Faurel, ed., et al. Let Newton Be? A new perspective on his life and works
New York: Oxford University Press, 1988, pg 87
call number: QC16 N7L47 1988