112 THE BORDERLAND OF SCIENCE. 



two planets. If ever we are to recognise the signs of 

 life in any of the orbs which people space, it will be 

 in Mars that such signs will be first traced. As Venus 

 comes near to us she assumes the form of the crescent 

 moon, we have but a foreshortened view of a portion 

 of her illuminated hemisphere, and her intensely bright 

 light defeats the scrutiny of the most skilful observer. 

 At the time of her nearest approach, she is lost wholly 

 to our view in the splendour of the solar rays, her 

 unilluminated or night hemisphere being directed 

 also towards us. With Jupiter, the case is different. 

 When at his nearest, he is seen under most favourable 

 conditions, and the enormous dimensions of his belts 

 render them very obvious and very beautiful features 

 for the scrutiny of the telescopist. But then he is 

 some 370 millions of miles from us at such a time, 

 whereas Mars, when most favourably placed for tele- 

 scopic study, is but 37 millions of miles away. A 

 square mile on the surface of Mars would appear a 

 hundred times larger than a square mile on the surface 

 of Jupiter, supposing both planets studied when at 

 their nearest. It is clear, then, that as respects surface- 

 details, Mars is examined under much more favourable 

 conditions than the giant planet Jupiter. 



But here the question is naturally suggested, whether 

 our own moon, which is but a quarter of a million of 

 miles from us, ought not first to be examined for signs 

 of life, or, at least, of being fitted for the support of 

 life. When the telescope was first invented, it is 

 certain that astronomers were more hopeful of recog- 



