Handbuch der physiologischen Optik / bearbeitet von H. Helmholtz, Professor der Physiologie zu Heidelberg

In Handbuch der physiologischen Optik, Herman von Helmholtz (1821-1894) "investigated the optical contents of the eye, measured by his invention, the ophthalmometer, the radii of curvature of the crystalline lens for near and far vision, explained the mechanism of accomodation by which the eye can focus within certain limits, discussed the phenomena of color vision and gave a clear account of the movements of the eyeballs so as to secure single vision with two eyes. In particular he revived and gave new force to the theory of color vision associated with the name of Thomas Young, showing the three primary colors to be red, green and violet, and he applied the theory to the explanation of color blindness."--Enc. Brit.