So far as I am aware, they share with Mars the distinction of being the only celestial bodies which have been made the subjects of a testamentary disposition. In the case of Mars, readers may remember that some years ago a French lady left a large sum of money to be given to the individual who should first succeed in establishing communication with the Planet of War; in that of the asteroids, the late Professor Watson, a mighty hunter of minor planets in his day, made provision for the supervision of the twenty-two planets captured by him, lest any of them should get lost, stolen, or strayed. Small telescopes are, of course, quite impotent to deal with such diminutive bodies as the asteroids; nor, perhaps, is it desirable that the ranks of the minor-planet hunters should be reinforced to any extent. CHAPTER X JUPITER Passing outwards from the zone of the minor planets, we come to the greatest and most magnificent member of the solar system, the giant planet Jupiter. To most observers, Jupiter will probably appear not only the largest, but also the most interesting telescopic object which our system affords. Some, no doubt, will put in a claim for Mars, and some will share Sir Robert Ball's predilection for Saturn; but the interest attaching to Mars is of quite a different character from that which belongs to Jupiter, and while Saturn affords a picture of unsurpassed beauty, there is not that interest of variety and change in his exquisite system which is to be found in that of his neighbour planet. Jupiter is constantly attractive by reason of the hope, or rather the certainty, that he will always provide something fresh to observe; and the perpetual state of flux in which the details of his surface present themselves to the student offers to us the only instance which can be conveniently inspected of the process of world-formation. Jupiter is at the very opposite end of the scale from such a body, for example, as our own moon. On the latter it would appear as though all things were approaching the fixity of death; such changes as are suspected are scarcely more than suspected, and, even if established, are comparatively so small as to tax the utmost resources of observation. On the former, such a thing as fixity or stability appears to be unknown, and changes are constantly occurring on a scale so gigantic as not to be beyond the reach of small instruments, at least in their broader outlines.