Boötes, the constellation in which Arcturus lies, is usually described as forming a kite-shaped figure of stars, which though faint, covers a great deal of sky. Boötes, as mentioned before, was a herdsman who invented the plow, and as a reward for this ingenious method of tilling the soil, was raised to a position below the stars of the Big Dipper. But according to another story, Boötes represents Arcas, the son of Callisto, whom Juno so cruelly turned into a bear. In modern days this legend seems to have been given preference for, during the seventeenth century, Helvetius invented the Hunting Dogs, the constellation of Canes Venatici, and the huge figure of Boötes has since been usually pictured on the star maps as holding two lively dogs in leash. These Dogs are interposed between Boötes and Ursa Major. Although the Hunting Dogs have no mythology, the two constellations are thus united in a common picture and Boötes and his dogs are said to be chasing the Bear. "Boötes leading his hunting dogs over the zenith in the leash of sidereal fire." --_CARLYLE._ In Ovid's version of the legend, the hunter was placed in the sky just as he was and not first metamorphosed into a bear and hung on the Pole Star as Ursa Minor. Not recognizing his mother in the form of Ursa Major, Boötes keeps on pursuing her in an eternal chase about the Pole. He is thus often called "The Watcher of the Bear" or "The Bear Driver." Those who choose to consider Callisto's son, Areas, as having been metamorphosed into a bear and hung on the pole of the heavens may then consider Boötes as representing the herdsman who invented the plow. The two Hunting Dogs, "Asterion" and "Chara," now held enchained by Boötes, form the constellation Canes Venatici, which lies just below the handle of the Big Dipper and above Arcturus and Berenice's Hair. The collar of the hunting dog Chara is marked by the star Cor Carolli, which means "Charles' Heart" and was named in memory of Charles I by Halley, the English astronomer, on the suggestion of the Court Physician, Sir Charles Scarborough. [Figure 57] This star is an attractive double as viewed in a small telescope with the delicate colorings of "flushed white and lilac." On the head of Asterion lies the famous whirlpool nebula, although this may only be seen in a large telescope. This nebula has its great arms of nebulous material flung widely into space and looks as if it were whirling rapidly about, but the motion, if any, is too slow for us really to see. With a few exceptions most of the spiral nebulæ are so very distant that they may only be seen through a very large telescope, but next to the stars, they are the most abundant objects in all the sky and are of great interest to astronomers.