[38] Galle, at Berlin, had, twelve years previously, made an observation which, if it had been interpreted correctly, would have given him priority. In June 1838 he remarked, on several nights, that the inner boundary of the inner ring was very indistinct and “gradually lost itself towards the body of the planet.” The space between the ring and Saturn was half filled with a dim veil, extending inwards from the ring. These observations failed to attract the notice their importance deserved, and Galle himself did not appreciate their full significance until the announcements of Bond and Dawes in 1850.
[39] Struve wrote, in 1883:—“That changes do take place in the ring-system is sufficiently proved.” Trouvelot, Schiaparelli, and others have also remarked variations of a sufficiently decided character to be placed on record.
[40] Herschel remarks that he saw this satellite in his 20-foot speculum two years before, viz. on Aug. 19, 1787, but he was then much engaged in observations of the satellites of Uranus.
Discovery of Uranus.—Mistaken for a Comet.—True character revealed.—Period &c.—Observations.—Belts on Uranus.—Further Observations required.—The Satellites.—Discovery of Neptune.—The planet observed in 1795.—Period &c.—Observations.—Supposed Ring.—Satellite.—A trans-Neptunian Planet.—Planetary Conjunctions.
_Discovery._—While Sir W. Herschel was a musician at Bath he formed the design of making a telescopic survey of the heavens. When engaged in this he accidentally effected a discovery of great importance, for on the night of March 13, 1781, an object entered the field of his 6·3-inch reflector which ultimately proved to be a new major planet of our system. The acute eye of Herschel, directly it alighted upon the strange body, recognized it as one of unusual character, for it had a perceptible disk, and could be neither fixed star nor nebula. He afterwards found the object to be in motion, and its appearance being “hazy and ill-defined” with very high powers he was led to regard it as a comet, and communicated his discovery to the Royal Society at its meeting on April 26, 1781. His paper begins as follows:—
“On Tuesday, March 13, 1781, between 10 and 11 in the evening, while I was examining the small stars in the neighbourhood of H Geminorum, I perceived one that appeared visibly larger than the rest. Being struck with its uncommon magnitude, I compared it to H Geminorum and the small star in the quartile between Auriga and Gemini, and finding it so much larger than either of them suspected it to be a comet.... The power I had on when I first saw the comet was 227.”