Photography of the Skies 



great reflector was turned upon certain of these 

 masses they were resolved into stars, and a good 

 many critics said that, given telescopes sufficiently 

 powerful, all nebulae would in the same manner 

 prove to be nothing else than stars. A few years 

 afterward the spectroscope was employed by the 

 astronomer, and soon it discriminated between 

 seeming nebulae, which are really star clusters, 

 and true nebulae, which are only the raw material 

 from which stars are condensed. In the evening 

 of August 29, 1864, the spectroscope, attached to 

 a telescope, was for the first time directed to a 

 nebula the planetary nebula in Draco, by Dr. 

 (now Sir) William Huggins. This is what he saw: 

 "The riddle of the nebulae was solved. The 

 answer, which Lad come to us in the light itself, 

 read, Not an aggregation of stars, but a luminous 

 gas. Stars after the order of our own sun, and of 

 the brighter stars, would give a different spectrum, 

 the light of this nebula had clearly been emitted 

 by a luminous gas. With an excess of caution, at 

 the moment I did not venture to go further than 

 to point out that we had here to do with bodies of 

 an order quite different from that of the stars. 

 Further observations soon convinced me that, 

 though the short span of human life is far too 

 minute relatively to cosmical events for us to ex- 

 pect to see in succession any distinct steps in so 

 august a process, the probability is indeed over- 

 whelming in favour of an evolution in the past, 

 and still going on, of the heavenly hosts. A time 

 surely existed when the matter now condensed 

 97 



