28o IN STARRY REALMS. 



approach, pass from the invisible into the visible region. 

 Thus, the general character presented by the appearance 

 of the star is not altered. No doubt there is a conceivable 

 velocity of approach so great that all the rays except a few 

 should be hurried into the ultra-violet, and then, of course, 

 the star would only have a violet or bluish colour ; and 

 there is a conceivable velocity of retreat from the earth by 

 which all the rays except a few should have their periods 

 of vibrations so lengthened that the only appeal to the eye 

 would be the glimmer of a ruddy object. The velocities, 

 however, that would be required for the display of such 

 phenomena, so enormously transcend those actually pos- 

 sessed by any known body in space, that we may at once 

 dismiss the supposition that the observed colours of the 

 stars are to be explained in this manner. In fact, we 

 have evidence presented by the spectroscope itself, which 

 shows that we must look for an explanation of the colours 

 of the stars in. quite a different direction. It was thus 

 known that the ingenious supposition that some stars 

 seemed red merely because they were hurrying away from 

 us, and that some stars seemed blue merely because they 

 were hurrying towards us, must be set aside. 



But, though the notion of Doppler was, we now know, 

 in a large measure incorrect, yet we are indebted to it for 

 a suggestion which has already borne much fruit in 

 modern astronomical research, and which bids fair to 

 extend our knowledge of the heavens to an extent that 

 never would have been dreamed of until the last few years. 

 It is quite true that the celestial velocities are insufficient 

 to cause any grand transmutation in the hues of celestial 

 objects. We must not look for their effects on so coarse a 



