a lofty theme, the same insight into general principles, as illumined the first paper he wrote on the subject thirty-five years before. Although his sun was nearing its going down, there was no loss of its morning brilliance. "Of all the celestial objects consisting of stars not visible to the eye," he writes, "the Milky Way is the most striking. . . . Its general appearance, without applying a telescope to it, is that of a zone surrounding our situation in the solar system, in the shape of a succession of differently condensed patches of brightness, intermixed with others of a fainter tinge." But his latest observations led him to believe that the Milky Way is a fathomless, and comparatively thin stratum of stars, of which his 40-feet reflector would sound the depths "to the 2300th order of distances and would then fail us." He imagined also he had "shown how, by an equalisation of the light of stars of different brightness, we may ascertain their relative distances from the observer, in the direction of the line in which they are seen." Among these last words was his expressed conviction that the Milky Way is the most brilliant, and beyond all comparison the most extensive sidereal system. He thus held to the end that it was one of many systems, of which it bulked in his eyes as a great continent in an ocean of ether, while the nebulæ are outlying islands. Within the bounds of the Milky Way he believed that all our stars, visible to the naked eye, are contained. If an 18-inch globe represented all these stars, it would require a line 45 feet long to be added to express the distance of the 734th order of stars, and, while he saw many of the 900th or 980th order, he was convinced that his 40-feet telescope would penetrate space
