On the laws which regular the polarization of light by reflection from transparent bodies. By David Brewster, LL. D. F. R. S. Edin. and F. S. A. Edin. In a letter addressed to the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S

Abstract

Though Huygens, who first explained the laws that regulate the extraordinary refraction of light at a surface of Iceland spar, discovered that light thus separated has properties different from common light; and though Newton observed that light thus modified has permanent properties, with reference to the plane in which it has been refracted, and expressed this peculiarity by saying that these rays have sides according to which its subsequent refractions are regulated;—it was Malus who gave to this modification the name of polarization, a term by which he could conveniently express the various affections which such light undergoes by refraction or reflection in different directions; and could thereby most distinctly describe the various phenomena relating to his important discovery, that light may also by reflection acquire the same properties that are given by refraction through Iceland spar and other doubly refracting crystals. Malus ascertained, that when light is incident on the surface of water at a certain angle, that portion of it which is reflected is completely polarized; and that when light is incident on the surface of other media, the angle at which complete polarization of the reflected portion takes place will be different, being greater when the reflecting substance has a higher refractive. But Malus did not succeed in detecting the rule by which the requisite angles of incidence for different bodies could be inferred from their refractive powers.