GALILEO AND HIS JUDGES. 95 



Ptolemaic system, and for this reason : According to 

 that system Venus was a planet revolving round the 

 Earth in an orbit outside that of Mercury, but within 

 that of the Sun. Now the phases of Venus did not 

 correspond with any supposed period of her revolu- 

 tion round the Earth, as the phases of the Moon 

 obviously do, nor did any one ever imagine that the 

 Earth went round Venus. They did, however, cor- 

 respond with the time of a probable orbit in which 

 either Venus revolved round the Sun or the Sun 

 round Venus ; and here again this latter alternative 

 was inadmissible. There remained, therefore, the 

 one only reasonable solution of the phenomenon, 

 namely, that Venus travelled in an orbit round the 

 Sun. This was further confirmed when, in December, 

 1639, our own countryman, Horrox, at that time a 

 young curate residing in the north of England, but 

 gifted with a knowledge of astronomy which would 

 have done credit to a man of double his age and 

 experience, observed a transit of the planet across 

 the Sun's disc. This occurred some few years after 

 Galileo's condemnation ; but it may be remarked that 

 Gassendi had already, in November, 1631, witnessed 

 a transit of Mercury. Thus it appeared that these 

 two planets revolved round the Sun, contrary to what 

 Ptolemy had supposed. And yet this was not con- 

 clusive in favour of Copernicanism, for the theory 

 of Tycho Brans' was precisely to this effect : that 

 the planets revolved round the Sun, and that the Sun 

 in his turn circulated round the Earth. This hypo- 



