CHAPTER V.
THE FIFTH SATELLITE OF JUPITER.
INCE the invention of the telescope some two hundred and eighty years ago the great planet Jupiter has never been the object of so much attention as it was during the autumn of 1892. It will be remembered that among the first-fruits of the new instrument for looking at objects which were a long way off, was the great discovery of the system of which Jupiter was the centre. The four satellites lie just on the dividing line between objects which can be seen with the unaided eye, and objects which require optical assistance to make them visible. It seems to be certain that there have been individuals gifted with rare powers of vision who under exceptionally favourable circumstances have been able to discern one or other of the satellites of Jupiter without optical aid. Testimony has been adduced which seems to show that long before the invention of Galileo's tube for studying the heavens, one or two of these satellites had been seen by the Chinese. But it would be futile to say that these glimpses of the moons of Jupiter really amounted to any anticipation of the great discovery of Galileo, Such mere casual observations never thoroughly
