NATURE OF THE SUN.
M. Arago has found, by experiments with the polariscope, that the light of gaseous bodies is natural light when it issues from the burning surface; although this circumstance does not prevent its subsequent complete polarisation, if subjected to suitable reflections or refractions. Hence we obtain a most simple method of discovering the nature of the sun at a distance of forty millions of leagues. For if the light emanating from the margin of the sun, and radiating from the solar substance at an acute angle, reach us without having experienced any sensible reflections or refractions in its passage to the earth, and if it offer traces of polarisation, the sun must be a solid or a liquid body. But if, on the contrary, the light emanating from the sun’s margin give no indications of polarisation, the incandescent portion of the sun must be gaseous. It is by means of such a methodical sequence of observations that we may acquire exact ideas regarding the physical constitution of the sun.—Note to Humboldt’s Cosmos, vol. iii.