Page:Sir William Herschel, his life and works (1881).djvu/212

190 polished surface, and on the other by a spherical surface of long radius, such as the exterior surface of a convex lens, for example. The colors are then arranged in concentric circles, and, though others had so produced them before, these rings have, ever since the publication of his remarkable work, been known by his name.

To explain the phenomena, was obliged to supplement his theory of the corpuscular nature of light, by supposing that the inconceivably minute particles constituting light are not always equally susceptible of reflection, but that they have periodically recurring "fits of easy reflection" and of "easy transmission." This conception, though by no means unphilosophical, seemed to too artificial and improbable for ready acceptance, and his effort was to supply a more probable explanation.

The developments of optical science have justified in his objections, but we cannot accord to him any considerable part in making clear the true nature of the phenomenon. Indeed, it must be recognized that