[alpha] and [beta] denote the front wheels of the Chariot generally known as the "pointers;" [gamma] and [delta] the hind wheels; [epsilon], [zeta], [eta] the three horses. All these stars are of the second order of magnitude (the specific meaning of this expression will be explained in the next chapter), except the last ([delta]) of the quadrilateral, which is of the third order. [Illustration: FIG. 3.--The Great Bear (or Dipper), and the Pole-Star.] Figure 3 gives the outline of this primitive constellation. In revolving in twenty-four hours round the Pole, which is situated at the prolongation of a line drawn from [beta] to [alpha], it occupies every conceivable position,--as if this page were turned in all directions. But the relative arrangement of the seven stars remains unaltered. In contemplating these seven stars it must never be forgotten that each is a dazzling sun, a center of force and life. One of them is especially remarkable: [zeta], known as Mizar to the Arabs. Those who have good sight will distinguish near it a minute star, Alcor, or the Cavalier, also called Saidak by the Arabs--that is, the Test, because it can be used as a test of vision. But further, if you have a small telescope at your disposal, direct it upon the fine star Mizar: you will be astonished at discovering two of the finest diamonds you could wish to see, with which no brilliant is comparable. There are several double stars; these we shall become acquainted with later on. Meantime, we must not forget our celestial geography. The Great Bear will help us to find all the adjacent constellations. [Illustration: FIG. 4.--To find the Pole-Star.] If a straight line is drawn (Fig. 4) from [beta] through [alpha], which forms the extremity of the square, and is prolonged by a quantity equal to the distance of [alpha] from the tip of the handle, we come on a star of second magnitude, which marks the extremity of a figure perfectly comparable with the Great Bear, but smaller, less brilliant, and pointing in the contrary direction. This is the Little Bear, composed, like its big brother, of seven stars; the one situated at the end of the line by which we have found it is the Pole-Star.