52 



and to rotate with a motion contrary to that of yourself and the 

 basin ; so that it may be more truly said that the basin and your- 

 self gyrate round the immovable water, than that the water ro- 

 tates within the basin." So says Galileo ; and truly, had all his 

 other experiments been followed by such inferences as this, he 

 must have occupied one of the lowest places in the ranks of 

 science, if any place at all, instead of one of the highest. He must 

 have been labouring under some strange delusion, when he per- 

 suaded himself to believe that a body which was visibly rotating be- 

 fore his eyes, and making all the points of its circumference in 

 succession pass its radius-vector, or the straight line between its 

 own centre and the centre of its orbit, and continually changing 

 their distance from that centre, all the way round, was neverthe- 

 less immovably at rest. He seems indeed to have escaped 

 the blunder of some of his successors, and to have been quite 

 well aware that there were only two possible ways in which he 

 could see a body all round, namely, by going round it himself, or 

 having it turned round about before him ; and accordingly, when 

 he inferred from his experiment that the water did not rotate, 

 his only alternative was to suppose that he himself and the basin 

 must have gone round about the water. But it seems not to have 

 struck him that this was impossible without leaving his central 

 position and crossing the orbit twice, once in going to the outside 

 and again in returning. Some of the schoolmen of old were of 

 opinion that angels could go from one place to another without 

 passing through the intervening space, and not without some 

 shew of reason, for angels were supposed to be purely spiritual 

 beings, without relation to time and space. Less reason than 

 even this had Galileo for his opinion, when he supposed it pos- 

 sible for a heavy material substance like his own body, occupying 

 a fixed position in space, to perform a gyration round about a 

 distant point or body, not only without going through the inter- 

 vening space, and measuring out by his movement the line of 

 gyration, but even without ever stirring from the spot he occupied ; 

 his whole process of circumgyration being just as purely spiritual 

 and imaginary as the angels' transit, and virtually the same 

 thing as a planet's performing an orbital revolution without going 

 round about the space which its orbit incloses, or through a single 

 one of the 360° of which its orbit consists. Homer, the prince of 

 poets, is said '^sometimes to snore as well as nod ;" so may it be 

 said of the great "Tuscan artist," aliquando bonus dormitat 

 Galilceus. 



Galileo would have discovered his error at once if, instead of 

 water, he had put into the basin a quantity of meal, flour, 

 sugar, sand, earth, gravel, or any other sluggish material, and 

 made it revolve, as before. In this case the matter would lie 



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