It is worth while following up this paradox in some detail, as it affords a very instructive example of the way in which a work started on purely utilitarian grounds extends itself till it crosses the undefined boundary and enters the region of pure science. We have no idea who made the earliest census of the sky. It is written for us in no book; it is not even engraved on any monument. And yet no small portion of it is in our hands to-day, and, strangest of all, we are able to fix fairly closely the time at which it was made, and the latitude in which its compiler lived. The catalogue is very unlike our star-catalogues of to-day. The places of the stars are very roughly indicated; and yet this catalogue has left a more enduring mark than all those that have succeeded it. The catalogue simply consists of the star names. An old lady who had attended a University Extension lecture on astronomy was heard to exclaim: 'What wonderful men these astronomers are! I can understand how they can find out how far off the stars are, how big they are, and what they weigh--that is all easy enough; and I think I can see how they find out what they are made of. But there is one thing that I can't understand--I don't know how they can find out what are their names!' This same difficulty, though with a much deeper meaning than the old lady in her simplicity was able to grasp, has occurred to many students of astronomy. Many have wished to know what was the meaning of, and whence were derived, the sonorous names which are found attached to all the brighter stars on our celestial globes: Adhara, Alderamin, Betelgeuse, Denebola, Schedar, Zubeneschamal, and many more. The explanation lies here. Some 5000 years ago, a man, or college of men, living in latitude 40° north, in order that they might better remember the stars, associated certain groups of them with certain fancied figures, and the individual star names are simply Arabic words designed to indicate whereabouts in its peculiar figure or constellation that special star was situated. Thus Adhara means 'back,' and is the name of the bright star in the back of the great Dog. Alderamin means 'right arm,' and is the brightest star in the right arm of Cepheus, the king. Betelgeuse is 'giant's shoulder,' the giant being Orion; Denebola is 'lion's tail.' Schedar is the star on the 'breast' of Cassiopeia, and Zubeneschamal is 'northern claw,' that is, of the Scorpion. So far is clear enough. The names of the stars for the most part explain themselves; but whence the constellations derived their names, how it was that so many snakes and fishes and centaurs were pictured out in the sky, is a much more difficult problem, and one which does not concern us here.