xii TOWARDS INFINITY 327 



of them ; yet, immense as are these distances, there is 

 endless space beyond. The light which we now receive 

 from many of the faint stars has probably taken 

 hundreds of years to reach us, though it has travelled 

 through space at the rate of 186,000 miles per second. 

 There are ether stars so far away that their rays, which 

 touch the earth to-night, left them long before the 

 commencement of our era. May it not be possible, 

 therefore, that beyond the whole of this starry universe 

 which we know, there are unknown universes even 

 surpassing our own in glory, but the light of which has 

 not yet come to us ? 



As to the existence of invisible universes beyond the 

 stars, we can only speculate ; but there is much dark 

 material within the boundary of our own universe, and 

 it has only been made manifest in recent years. " Evi- 

 dence of things unseen " has been and is being accumu- 

 lated, and we now know that there are in stellar space 

 vast clouds of cosmic dust, and many dark globes which 

 can never be seen or photographed. The parts of a 

 nebula visible to the eye or a camera are, in all 

 probability, only the luminous gases proceeding from 

 concentrated portions of a mass of dark particles 

 cosmic dust occupying a much greater region of 

 space. 



What is seen or photographed is thus only a small 

 fraction of the whole bulk of a nebula. In the course 

 of aeons the irregular group of cosmic fragments is 

 whirled into shape, and as the mass contracts, portions 

 are detached which form stars, and these, in turn, are 

 the parents of worlds like the earth and other planets. 

 First, a congeries of cosmic dust ; then the faintly 

 luminous gleam of a nebula, arising from gases evolved 

 and illuminated by heat or electricity ; then a star in 



