Herschel was now on the path in which his genius was calculated to shine. In the year 1774, he had the inexpressible pleasure of beholding the planet Saturn through a five-feet Newtonian reflector, made by his own hands. This was the beginning of a long and brilliant course of triumphs in the same walk of art, and also in that of astronomical discovery. Herschel now became so much more ardently attached to his philosophical pursuits, that, regardless of the sacrifices of emolument he was making, he began gradually to limit his professional engagements and the number of his pupils. Meanwhile, he continued to employ his leisure in the fabrication of still more powerful instruments than the one he first constructed; and in no long time he produced telescopes of from seven to twenty feet focal distance. In fashioning the mirrors for these instruments, his perseverance was indefatigable. For his seven-feet reflector, it is asserted that he actually finished and made trial of no fewer than two hundred mirrors before he found one that satisfied him. When he sat down to prepare a mirror, his practice was to work at it for twelve or fourteen hours, without quitting his occupation for a moment. He would not even take his hand from what he was about, to help himself to food; and the little that he ate on such occasions was put into his mouth by his sister. He gave the mirror its proper shape more by a natural tact than by rule; and when his hand was once in, as the phrase is, he was afraid that the perfection of the finish might be impaired by the least intermission of his labors.
It was on the 13th of March, 1781, that Herschel made the discovery to which he owes, perhaps, most of his popular reputation. He had been engaged for nearly a year and a-half in making a regular survey of the heavens, when, on the evening of the day that has been mentioned, having turned his telescope—an excellent seven-feet reflector, of his own constructing—to a particular part of the sky, he observed among the other stars, one which seemed to shine with a more steady radiance than those around it; and, on account of that, and some other peculiarities in its appearance, which excited his suspicion, he determined to observe it more narrowly. On reverting to it after some hours, he was a good deal surprised to find that it had perceptibly changed its place—a fact, which, the next day, became still more indisputable. At first he was somewhat in doubt whether or not it was the same star, which he had seen on these different occasions; but after continuing these observations for a few days longer, all uncertainty upon that head vanished. He now communicated what he had observed to the royal astronomer, Dr. Maskelyne, who concluded that the luminary could be nothing else than a new comet. Continued observation of it, however, for a few months, dissipated this error; and it became evident that it was, in reality, a hitherto undiscovered planet.
This new world, so unexpectedly found to form a part of the system to which our own belongs, received from Herschel the name of Georgium Sidus, or Georgian Star, in honor of the king of England; but by continental astronomers, it has been more generally called either Herschel, after its discoverer, or Uranus. He afterwards discovered, successively, no fewer than six satellites or moons, belonging to his new planet.
The anouncement of the discovery of the Georgium Sidus, at once made Herschel’s name universally known. In the course of a few months the king bestowed upon him a pension of £300 a-year, to enable him entirely to relinquish his engagements at Bath; and upon this, he came to reside at Slough, near Windsor. He now devoted himself entirely to science, and the constructing of telescopes, and observations of the heavens, continued to form the occupations of the remainder of his life.
Astronomy is indebted to him for many more most interesting discoveries besides the celebrated one of which we have just given an account, as well as for a variety of speculations of the most ingenious, original, and profound character. But of these we cannot here attempt any detail.
He also introduced some important improvements into the construction of the reflecting telescope, besides continuing to fabricate that instrument of dimensions greatly exceeding any that he had formerly attempted, with powers surpassing, in nearly a corresponding degree, what had ever been before obtained. The largest telescope which he had ever made was his famous one of forty feet long, which he erected at Slough, for the king.
It was begun about the end of the year 1785, and on the 28th of August 1789 the enormous tube was poised on the complicated but ingeniously-contrived mechanism by which its movements were to be regulated, and ready for use. On the same day a new satellite of Saturn was detected by it, being the sixth that had been observed attendant on that planet. A seventh was afterward discovered, by means of the same instrument. This telescope has since been taken down, and replaced by another of only half the length, constructed by the distinguished son of the subject of our present sketch.
So extraordinary was the ardor of this great astronomer in the study of his favorite science, that for many years, it has been asserted, he never was in bed at any hour during which the stars were visible, and he made almost all his observations, whatever the season of the year, not under cover, but in his garden, in the open air—and generally without an attendant. By these investigations Herschel became acquainted with the character of the more distant stars, upon which he wrote a variety of papers. In 1802, he presented to the Royal Society a catalogue of five thousand new nebulæ, nebulous stars, planetary nebulæ, and clusters of stars; thus opening up a boundless field of research, and making the world aware of the sublime truth of there being an infinitude of heavenly bodies far beyond the reach of ordinary vision, and performing in their appointed places the offices of suns to unseen systems of planets.
These discoveries established Herschel’s claims to rank amongst the most eminent astronomers of the age, and amply merited the distinctions conferred upon him by learned bodies and the reigning prince. In 1816, George IV, then prince regent, invested him with the Hanoverian and Guelphic order of knighthood. He was now, from being originally a poor lad in a regimental band, rewarded for his long course of honorable exertion in the cause of science. Herschel (now Sir William) did not relinquish his astronomical observations until within a few years of his death, which took place on the 23d of August, 1822, when he had attained the age of eighty-three. He died full of years and honors, bequeathing a large fortune, and leaving a family which has inherited his genius.