To the Ancients Saturn was the outermost planet of the System, nothing beyond it being known. Nor indeed was it to be assumed that any more could possibly exist, because Mercury, Venus, the Earth, Mars, Jupiter, and Saturn, with the Sun, made 7 celestial bodies of prime importance; and 7 was the number of perfection; and there was thus provided one celestial body to give a name to each of the days of the week.

But Science is not sentimental; and when men of Science come upon what looks like a discovery they do their best to bring their discovery to a successful issue, however much people’s prejudices may seem to stand in the way at the moment.

On a certain evening in March, 1781, Sir William Herschel, then gradually coming into notice as a practical astronomer, was engaged in looking at different fields of stars in the constellation Gemini when he lighted on one which at once attracted his special attention. Altering his eyepiece, and substituting a higher magnifying power he found the apparent size of the mysterious object enlarged, which conclusively proved that it was not a star; for it is a well-known optical property of all stars that whatever be the size of telescope employed on them, and however high the magnifying power no definite disc of light can be obtained when in focus. Herschel’s new find, therefore, was plainly not a star, and no idea having in those days come into men’s minds of there being any new planets awaiting discovery, he announced as a matter of course that he had found a new comet, so soon as he ascertained that the new body was in motion. The announcement was not made to the Royal Society till April 26, more than six weeks after the date of the actual discovery, an indication, by the way, of the dilatory circulation of news a hundred years ago. The supposed comet was observed by Maskelyne, the Astronomer Royal, four days after Herschel had first seen it, and Maskelyne seems to have at once got the idea into his head that he was looking at a planet and not at a comet. As soon as possible after the discovery of a new comet the practice of astronomers is to endeavour to determine what is the shape of the orbit which it is pursuing. All attempts to carry out this in the case of Herschel’s supposed new comet proved abortive, because it was found impossible to harmonise, except for a short period of time, the movements of the new body with the form of curve usually affected by most comets, namely, the parabola. It is true, as we shall see later on in speaking of comets, that a certain number of those bodies do revolve in the closed curve known as the ellipse, but it is usual to calculate the parabolic form first of all, because it is the easier to calculate; and to persevere with it until it plainly appears that the parabola will not fit in with the observed movements of the new object. This practice was carried out in the case of Herschel’s new body, and it was eventually found that not only was its orbit not parabolic; that not only was its orbit not an elongated ellipse of the kind affected by comets; but that it was nearly a circle, and as the body itself showed a defined disc the conclusion was inevitable: it was in real truth a new planet. It has not taken long to write this statement, and it will take still less time for the reader to read what has been written, but the result just mentioned occupied the attention of astronomers many months in working out, step by step, in such a way as to make sure that no mistake had been made.

When it was once clearly determined that Herschel had added a new planet to the list of known planets it became an interesting matter of inquiry to find out whether it had ever been seen before; and to settle the name it should bear. A little research soon showed that the new planet had been seen and recorded as a fixed star by various observers on 20 previous occasions, beginning as far back as Dec. 13, 1690, when Flamstead registered at Greenwich as a star. These various observations, spread over a period of 91 years, and all recorded by observers of skill and eminence materially helped astronomers in their efforts to calculate accurately the shape and nature of the new planet’s orbit. One observer, a Frenchman named Le Monnier, saw the planet no less than 12 times between 1750 and 1771, and if he had had (which it is known he had not) an orderly and methodical mind, the glory of this discovery would have been lost to England and obtained by France. Arago has left it on record that he was once shown one of these chance observations of Uranus, which had been recorded by Le Monnier on an old paper bag in which hair powder had been sold by a perfumer.

A long discussion took place on the question of a name for the new planet. Bode’s suggestion of “Uranus” is now in universal use, but it is within the recollection of many persons living that this planet bore sometimes the name of the “Georgium Sidus” and sometimes the name of “Herschel.” The former designation was proposed by Herschel himself in compliment to his sovereign and patron George III. of England; whilst a French astronomer suggested the latter name. However, neither of these appellations was acceptable to the astronomers of the Continent, who declared in favour of a mythological name, though it was a long time before they agreed to accept Bode’s “Uranus.” The symbol commonly used to represent the planet is formed of Herschel’s initial with a little circle added below, though the Germans employ something else, “made in Germany,” to quote a too familiar phrase.

The visible disc of Uranus is so small that none but telescopes of the very largest size can make anything of it. A few sentences therefore will dispose of this part of the subject. The disc is usually bluish in tinge, and most observers who look at it consider it uniformly bright, but there is satisfactory testimony to the effect that under the most favourable circumstances of instrument and atmosphere two or more belts, not unlike the belts of Jupiter, may be traced. From the position in which these belts have been seen it is inferred that the satellites of Uranus (presently to be mentioned) are unusually much inclined to the planet’s equator, and revolve in a retrograde direction, contrary to what is the ordinary rule of the planets and satellites. It is assumed as the basis of these ideas, (and by analogy it is reasonable to do this) that the belts are practically parallel to the planet’s equator, and at right angles to the planet’s axis of rotation. To speak of the planet’s axis of rotation is, in one sense, another assumption, because available observations can scarcely be said to enable us to demonstrate that the planet does rotate on its axis, yet we can have no moral doubt about it. Taylor has suggested grounds for the opinion that “there can be very little doubt that Uranus is to a very large extent self-luminous, and that we do not see it wholly by reflected light.” To this Gore adds the idea that there is “strong evidence in favour of the existence of intrinsic heat in the planet.”

Uranus is attended by several satellites. It was once thought that there were eight, of which six were due to Sir W. Herschel, the other two being of modern discovery. Astronomers are, however, now agreed that no more than four satellites can justly be recognised as known to exist, and they are so minute in size that only the very largest telescopes will show them; and therefore our knowledge of them is extremely limited. Sir W. Herschel’s idea that he had seen six satellites appears to have resulted from his having on some occasions mistaken some very small stars for satellites. Two only of his six are thought to have been real satellites. The other two recognised satellites were found both in 1847, one by Lassell, and the other by O. Struve.

Uranus revolves round the Sun in rather more than 84 years, at a mean distance of 1781 millions of miles. Its apparent diameter, seen from the Earth, does not vary much from 3½ which corresponds to about 31,000 miles. It has been calculated that the light received from the Sun by Uranus would be about the amount furnished by 300 full Moons seen by us on the Earth, though another authority increases this to 1670 full Moons. From Uranus Saturn can be seen, and perhaps Jupiter, both as inferior planets, just as we see Venus and Mercury; but all the other inner planets, including Mars and the Earth, would be hopelessly lost to view, because perpetually too close to the Sun. Possibly, however, they might, on rare occasions, be seen in transit across the Sun’s disc. Neptune, of course, would be visible and be the only superior planet. The Sun itself would appear to an observer on Uranus as a very bright star, with a disc of 1¾' of arc in diameter.