Why (_the whole group_) is called the Great Bear is not so easy to explain. The classical legend has it that the nymph, Calisto, having violated her vow, was changed by Diana into a bear, which, after death, was immortalized in the sky by Zeus. Another suggestion is that the earliest astronomers, the Chaldeans, called these stars "the shining ones," and their word happened to be very like the Greek _arktos_ (a bear). Another explanation is that vessels in olden days were named for animals, etc. They bore at the prow the carved effigy of the namesake, and if the Great Bear, for example, made several very happy voyages by setting out when a certain constellation was in the ascendant, that constellation might become known as the Great Bear's constellation. Certainly, there is nothing in its shape to justify the name. Very few of the constellations indeed are like the thing they are called after. Their names were usually given for some fanciful association with the namesake, rather than for resemblance to it. [Illustration] The pole-star is really the most important of the stars in our sky; it marks the north at all times; all the other stars seem to swing around it once in twenty-four hours. It is the end of the Little Bear's tail; this constellation is sometimes called the Little Dipper. But the Pole-star or Polaris, is not a very bright one, and it would be hard to identify but for the help of the Pointers of the Big Dipper. The outside stars (Alpha and Beta) of the Dipper point nearly to Polaris, at a distance equal to five times the space that separates these two stars of the Dipper's outer side. Indian names for the Pole-star are the "Home Star," and "The Star That Never Moves," and the Big Dipper they call the "Broken Back." The great Bear is also to be remembered as the hour-hand of the woodman's clock. It goes once around the North Star in about twenty-four hours, the same way as the sun, and for the same reason--that it is the earth that is going and leaving them behind. The time in going around is not exactly twenty-four hours, so that the position of the Pointers varies with the seasons, but, as a rule, this for woodcraft purposes is near enough. The bowl of the Dipper swings four-fifths of the width of its own opening in one hour. If it went a quarter of the circle, that would mean you had slept a quarter of a day, or six hours. Every fifteen days the stars seem to be an hour earlier: in three months they gain one-fourth of the circle, and in a year gain the whole circle. According to Flammarion, there are about seven thousand stars visible to the naked eye, and of these twenty are stars of the first magnitude. Fourteen of them are visible in the latitude of New York, the others (those starred) belong to the South Polar region of the sky. The following table of the brightest stars is taken from the Revised Harvard Photometry of 1908, the best authority on the subject. THE FIRST TWENTY STARS IN ORDER OF BRIGHTNESS