58 COSMOS. 



and even the smallest amount of water they contain, of 

 scrutinizing the depths of the ocean and its rocks by means 01 



sortie de la surface enflammee, est de la lumiere naturelle, cc 

 qui n'empeche pas qu'elle ne se polarise ensuite completement 

 si on la soumet a des reflexions ou a des refractions conven- 

 ables. De la une methode tres simple pour decouvrir a 40 

 millions de lieues de distance la nature du soleil. La lumiere 

 provenant du bord de cet astre, la lumiere emanee de la matiere 

 solaire sous un angle aigu, et nous arrivant sans avoir eprouve 

 en route des reflexions ou des refractions sensibles, offre-t-elle 

 des traces de polarisation, le soleil est un corps solide ou 

 liquide. S'il n'y a, au contraire, aucun indice de polarisation 

 dans la lumiere du bord, la par tie incandescente du soleil est 

 gazeuse. C'est par cet enchainement methodique d' observations 

 qu'on peut arriver a des notions exactes sur la constitution 

 physique du soleil." 



"By the aid of my polariscope I discovered (before 

 1820) that the light of all terrestrial objects in a state of 

 incandescence, whether they be solid or liquid, is natural 

 as long as it emanates from the object in perpendicular rays. 

 The light emanating from an incandescent surface at an acute 

 angle presents on the other hand manifest proofs of polarisation. 

 I will not pause to remind you that this circumstance has led 

 me to the remarkable conclusion that light is not generated on 

 the surface of bodies only, but that some portion is actually 

 engendered within the substance itself, even in the case of 

 platinum. I need only here observe, that in repeating the 

 same series of experiments (and with the same instruments) on 

 the light emanating from a burning gaseous substance, I could 

 not discover any characteristics of polarised light, whatever 

 might be the angle at which it emanated ; and I found 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 re- 

 flections or refractions. Hence we obtain a most simple method 

 of discovering the nature of the sun at a distance of 40 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 



