Arago, Mitchel, Nichol, Chambers, and other writers quite misinterpreted Herschel’s views on the nebulæ when they said that he believed them to be all external galaxies. In 1785 Herschel believed many to be connected with the sidereal system; considering that in some parts of the Galaxy “the stars are now drawing towards various secondary centres, and will in time separate into different clusters.” He was coming to the view that the star-clusters were secondary aggregations within the Galaxy, probably the true theory. He pointed out that in Scorpio, the cluster Messier 80 is bounded by a black chasm, four degrees wide, from which he believed the stars had been drawn in the course of time to form the cluster. His sister records that one night, after a “long, awful silence,” he exclaimed on coming on this chasm—“Hier ist wahrhaftig ein Loch im Himmel!” (Here, truly, is a hole in the heavens.) Herschel was now gradually giving up his theory of external galaxies and his “disc-theory” of the Universe; but he still believed even the nebulous objects to be irresolvable only through immensity of distance. In 1791, however, he drew attention to a remarkable star in Taurus, surrounded by a nebulous atmosphere, regarding which he wrote, “View, for instance, the nineteenth cluster of my sixth class, and afterwards cast your eye on this cloudy star. Our judgment, I will venture to say, will be that _the nebulosity about the star is not of a starry_ _nature_. We therefore either have a central body which is not a star, or have a star which is involved in a shining fluid, of a nature totally unknown to us.” And with caution he added that “the envelope of a cloudy star is more fit to produce a star by its condensation than to depend upon the star for its existence.” This was written in 1791, five years before Laplace propounded his nebular theory. Meanwhile Herschel, believing that “these nebulous stars may serve as a clue to unravel other mysterious phenomena,” found that the theory of a “shining fluid” would suit the appearance of the irresolvable planetary nebulæ and the great nebula in Orion much better than the extravagant idea of “external universes.” Herschel now considered the Orion nebula to be much nearer to the Solar System than he formerly did, and ceased to regard it as external to the Galaxy. For twenty years Herschel patiently observed the nebulæ, and it was not until 1811 that he propounded his nebular hypothesis of the evolution of the Sun and stars. He found the gaseous matter in all stages of condensation, from the diffused cloudy nebulæ like that in Orion, through the planetary nebula and the regular nebula, to the perfect stars, like Sirius and the Sun. Herschel’s nebular theory was a grand conception, and a magnificent attack on the secrets of nature.