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