Curious to say, Al-Sufi rated the Pole Star as 3rd magnitude; for it is now only slightly less than the 2nd. At present it is about the same brightness as β of the same constellation (Ursa Minor) which Al-Sufi rated 2nd magnitude. It was, however, also rated 3rd magnitude by Ptolemy (or Hipparchus), and it may possibly have varied in brightness since ancient times. Admiral Smyth says that in his time (1830) it was "not even a very bright third size" (!)[395] Spectroscopic measures show that it is approaching the earth at the rate of 16 miles a second; but this would have no perceptible effect on its brightness in historical times. This may seem difficult to understand, and to some perhaps incredible; but the simple explanation is that its distance from the earth is so great that a journey of even 2000 years with the above velocity would make no _appreciable_ difference in its distance! This is undoubtedly true, as a simple calculation will show, and the fact will give some idea of the vast distance of the stars. The well-known 9th magnitude companion to the Pole Star was seen _by day_ in the Dorpat telescope by Struve and Wrangel; and "on one occasion by Encke and Argelander."[396] The star β Ursæ Minoris was called by the Arabians _Kaukab al-shamáli_, the North Star, as it was--owing to the precession of the Equinoxes--nearer to the Pole in ancient times than our present Pole Star was _then_. The "Plough" (or Great Bear) is supposed to represent a waggon and horses. "Charles' Wain" is a corruption of "churl's wain," or peasant's cart. The Arabians thought that the four stars in the quadrilateral represented a bier, and the three in the "tail" the children of the deceased following as mourners! In the Greek mythology, Ursa Major represented the nymph Callisto, a daughter of Lycaon, who was loved by Jupiter, and turned into a bear by the jealous Juno. Among the old Hindoos the seven stars represented the seven Rishis. It is the Otawa of the great Finnish epic, the "Kalevala." It was also called "David's Chariot," and in America it is known as "The Dipper." Closely north of the star θ in Ursa Major is a small star known as Flamsteed 26. This is not mentioned by Al-Sufi, but is now, I find from personal observation, very visible, and indeed conspicuous, to the naked eye. I find, however, that owing to the large "proper motion" of the bright star (1"·1 per annum) the two stars were much closer together in Al-Sufi's time than they are at present, and this probably accounts for Al-Sufi's omission. This is an interesting and curious fact, and shows the small changes which occur in the heavens during the course of ages.