its history--its death; after death it simply goes to add an infinitesimal trifle to the dust of the earth. {81} CHAPTER VI THE SYSTEM OF THE STARS The first step towards our knowledge of the starry heavens was made when the unknown and forgotten astronomers of 2700 B.C. arranged the stars into constellations, for it was the first step towards distinguishing one star from another. When one star began to be known as "the star in the eye of the Bull," and another as "the star in the shoulder of the Giant," the heavens ceased to display an indiscriminate crowd of twinkling lights; each star began to possess individuality. The next step was taken when Hipparchus made his catalogue of stars (129 B.C.), not only giving its name to each star, but measuring and fixing its place--a catalogue represented to us by that of Claudius Ptolemy (A.D. 137). The third step was taken when BRADLEY, the third Astronomer Royal, made, at Greenwich, a catalogue of more than 3000 star-places determined with the telescope. A century later ARGELANDER made the great Bonn Zone catalogue of 330,000 stars, and now a great photographic catalogue and chart of the entire heavens have been arranged between eighteen observatories of different countries. This great chart when complete will probably present 30 millions of stars in position and brightness. {82} The question naturally arises, "Why so many stars? What conceivable use can be served by catalogues of 30 millions or even of 3000 stars?" And so far as strictly practical purposes are concerned, the answer must be that there is none. Thus MASKELYNE, the fifth Astronomer Royal, restricted his observations to some thirty-six stars, which were all that he needed for his _Nautical Almanac_, and these, with perhaps a few additions, would be sufficient for all purely practical ends. But there is in man a restless, resistless passion for knowledge--for knowledge for its own sake--that is always compelling him to answer the challenge of the unknown. The secret hid behind the hills, or across the seas, has drawn the explorer in all ages; and the secret hid behind the stars has been a magnet not less powerful. So catalogues of stars have been made, and made again, and enlarged and repeated; instruments of ever-increasing delicacy have been built in order to determine the positions of stars, and observations have been made with ever-increasing care and refinement. It is knowledge for its own sake that is longed for, knowledge that can only be won by infinite patience and care. The chief instrument used in making a star catalogue is called a transit circle; two great stone pillars are set up, each carrying one end of an axis, and the axis carries a telescope. The telescope can turn round like a wheel, in one direction only; it points due north or due south. A circle carefully divided into degrees and fractions of a degree is attached to the telescope.