XII. A method of examining refractive and dispersive powers, by prismatic reflection

Abstract

In examining the power with which various substances refract and disperse light, I have for some time past employed a me­thod unnoticed by writers on optical subjects; and, as it is not only convenient in common cases of refraction, but also capable of affording results not attainable by other means, I have been induced to draw up a short account of the method itself, and of the most remarkable instances of its application. This method was suggested by a consideration of Sir Isaac Newton’s prismatic eye-glass, the principle of which depends on the reflection of light at the inner surface of a dense re­fracting medium.