Ragnarok : the age of fire and gravel

68 THE COMET.

Amédée Guillemin says :

“ Comets have been observed whose heads, instead of being nebulous, have presented the appearance of stars, with which, indeed, they have been confounded.” *

When Sir William Herschel discovered the planet Urania, he thought it was a comet. Mr. Richard A. Proctor says :

“The spectroscopic observations made by Mr. Huggins on the light of three comets show that a certain portion, at least, of the light of these objects is inherent. .. . The nucleus gave in each case three bands of light, indicating that the substances of the nuclei consisted of glowing vapor.” t

In one case, the comet-head seemed, as in the case of the comet examined by Padre Secchi, to consist of pure carbon.

In the great work of Dr. H. Schellen, of Cologne, annotated by Professor Huggins, we read :

“That the nucleus of a comet can not be in itself a dark and solid body, such as the planets are, is proved by its great transparency ; but this does not preclude the possibility of its consisting of énnumerable solid particles separated from one another, which, when illuminated by the sun, give, by the reflection of the solar light, the impression of a homogeneous mass. It has, therefore, been concluded that comets are either composed of a substance which, like gas in a state of extreme rarefaction, is perfectly transparent, or of small solid particles individually separated by intervening spaces through which the light of a star can pass without obstruction, and which, held together by mutual attraction, as well as by gravitation toward a denser central conglomeration, moves through space like a cloud of dust. In any case the connection lately noticed by Schiaparelli, between comets and meteee eS

* “The Heavens,” p. 259. + Note to Guillemin’s “ Heavens,” p. 261.