author - "Garrett P. Serviss"

aphs, particularly those of the singular regionaround the star Rho Ophiuchi. Here are to be seen somber lanes andpatches, apparently forming a connected system which covers an immensespace, and which their discoverer thinks may constitute a ``darknebula.'' This seems at first a startling suggestion; but, after all,why should their not be dark nebulæ as well as visible ones? In truth,it has troubled some astronomers to explain the luminosity of thebright nebulæ, since it is not to be supposed that matter in sodiffuse a state can be incandescent through heat, and phosphorescentlight is in itself a mystery. The supposition is also in accord withwhat we know of the existence of dark solid bodies in space. Manybright stars are accompanied by obscure companions, sometimes asmassive as themselves; the planets are non-luminous; the same is trueof meteors before they plunge into the atmosphere and become heated byfriction; and many plausible reasons have been found for believingthat space contains as ma