" 146, bottom of page. This nebulosity was first discovered by Dr. Max Wolf of Heidelberg. See _Astr. Nachr._ 3736. " 181, line 17, _for_ "observation" _read_ "aberration." ASTRONOMICAL DISCOVERY CHAPTER I URANUS AND EROS [Sidenote: Popular view of discovery.] Discovery is expected from an astronomer. The lay mind scarcely thinks of a naturalist nowadays discovering new animals, or of a chemist as finding new elements save on rare occasions; but it does think of the astronomer as making discoveries. The popular imagination pictures him spending the whole night in watching the skies from a high tower through a long telescope, occasionally rewarded by the finding of something new, without much mental effort. I propose to compare with this romantic picture some of the actual facts, some of the ways in which discoveries are really made; and if we find that the image and the reality differ, I hope that the romance will nevertheless not be thereby destroyed, but may adapt itself to conditions more closely resembling the facts. [Sidenote: Keats' lines.] The popular conception finds expression in the lines of Keats:-- Then felt I like some watcher of the skies When a new planet swims into his ken. Keats was born in 1795, published his first volume of poems in 1817, and died in 1821. At the time when he wrote the discovery of planets was comparatively novel in human experience. Uranus had been found by William Herschel in 1781, and in the years 1800 to 1807 followed the first four minor planets, a number destined to remain without additions for nearly forty years. It would be absurd to read any exact allusion into the words quoted, when we remember the whole circumstances under which they were written; but perhaps I may be forgiven if I compare them especially with the actual discovery of the planet Uranus, for the reason that this was by far the largest of the five--far larger than any other planet known except Jupiter and Saturn, while the others were far smaller--and that Keats is using throughout the poem metaphors drawn from the first glimpses of "vast expanses" of land or water. Perhaps I may reproduce the whole sonnet. His friend C. C. Clarke had put before him Chapman's "paraphrase" of Homer, and they sat up till daylight to read it, "Keats shouting with delight as some passage of especial energy struck his imagination. At ten o'clock the next morning Mr. Clarke found the sonnet on his breakfast-table." SONNET XI _On first looking into Chapman's "Homer"_