The eighth satellite, Japetus, was shown by Herschel to rotate on its axis in a period equal to that of its revolution, and his observations were confirmed by modern observers. “I cannot,” Herschel said, “help reflecting with some pleasure on the discovery of an analogy which shows that a certain uniform plan is carried on among the secondaries of our Solar System; and we may conjecture that probably most of the satellites are governed by the same law.” In April 1805 Herschel observed the globe of Saturn to present not a spherical but a “square-shouldered” aspect. It was for long believed that this was an optical illusion; but Proctor and others have shown that it is quite possible for storms in Saturn’s atmosphere to cause the planet’s apparent distortion in shape. Herschel paid much attention to the planet Uranus, which he discovered on March 13, 1781. The discovery of Uranus, which was mentioned in a previous chapter, was in a sense the most striking of Herschel’s achievements. Uranus was the first planet discovered within the memory of man: besides, the discovery enlarged the diameter of the Solar System from 886 to 1772 millions of miles. Throughout his lifetime Herschel referred to the planet as the “Georgium Sidus,” out of gratitude to George III. for appointing him King’s Astronomer; but the astronomers of France and Germany, who, as Sir Robert Ball remarks, “saw no reason why the King of England should be associated with Jupiter and Saturn,” opposed this term. Lalande called the planet “Herschel,” but Herschel’s countrymen, the Germans, named it Uranus, in keeping with the custom of designating the planets from the Greek mythology. The name of Uranus ultimately prevailed. In January 1787 Herschel discovered two satellites to Uranus, with the aid of his 20-foot telescope. These satellites he believed to revolve round Uranus in 8 days and 13 days respectively, and accordingly he made a drawing of what their positions should be on February 10. On that day he found them in their predicted places. In 1797 he announced that the satellites revolved round Uranus in orbits at right angles to the ecliptic, and in a retrograde direction. In subsequent years Herschel believed that he had discovered other four satellites to Uranus, but he was unable to confirm his belief. As Mr Gore says, some of the satellites “must, therefore, have been either optical ‘ghosts’ or else small fixed stars which happened to be near the planet’s path at the time of observation. Herschel also suspected that he could see traces of rings round Uranus like those round Saturn, but his observation was never confirmed, either by himself or other observers.”