But the most interesting among these near neighbours of the south is a little yellow star in Pictor, too faint to be seen without a good binocular or a telescope, and bearing the very modern name of CZ 5ʰ.243. This stands for Cordoba Zones 5.243 hours, and means that it was catalogued at Cordoba Observatory in South America and its position fixed in the fifth hour of Right Ascension. After this it was observed by Mr. Innes at the Cape, and he was startled to find (like Hipparchus comparing his work with that of Timocharis) that its position no longer agreed with that found at Cordoba. “Can this be motion?” he asked, and found that the star had indeed a larger visible motion across the sky than any other, not even excepting the famous “runaway star” in Ursa Major. Apparent motion, however, depends upon distance as well as real speed, and when the distance of CZ 5ʰ.243 had been calculated it was found that its real speed, amazing as it is, yet falls slightly short of that of the northern star. The rates are 163 and 174 miles per second. A few other stars are known to move at speeds approaching 100 miles a second, and one was announced in December 1913 to have a velocity of 200 miles a second, but runaway stars are rare. They do not seem to show any preference for special parts of the sky or special stellar types, and it is impossible to say what causes them to rush with such headlong haste through space, or what is their goal. The average rate for a star is about 13 miles a second, but, as we have seen, it differs with different types, the average speed increasing progressively from the blue to the red classes. Another remarkable fact lately discovered is that the different types of stars are not indiscriminately scattered through space. Our own sun seems to be surrounded, to a distance of about 100 light-years, by suns more or less like himself, while the greater number of the red Antarian stars lie at a much greater distance from us. Most distant of all, considered as a class, are the bluest of the Orion stars; for though the distances of individuals vary greatly, the average distance of these stars from us is more than 500 light-years. Yet they are often very bright, so this is another proof of their great intrinsic brilliancy. VI DOUBLE AND MULTIPLE STARS Among the brighter stars at least one in four is double, and I shall only mention a few which for different reasons are of special interest. The brightest double in the sky has already been mentioned, α Centauri, and we have also described another southern pair scarcely less brilliant, α Crucis, Sirius with his very dim companion, Rigel and Antares with theirs of contrasting colours. Other fine southern doubles are: β Piscis australis, a white star with reddish companion, visible in a 3-inch telescope. δ Corvi, an unequal distant pair, pale yellow and bluish, easily separated in a 4½-inch telescope. σ Scorpii (near Antares), white and blue.