The Astronomical Outlook 



serious. The case differs immensely from that 

 of a reflector. So far, however, as the mere 

 ability to see things goes, it may well be doubted 

 whether any great gain will follow mere increase 

 of size, unless the new giants are to be mounted 

 at places where the atmospheric conditions are 

 far more perfect than at most of those hitherto 

 occupied. 



But the cry of the spectroscope and the photo- 

 graphic plate is always, "More light!" With 

 telescopes such as are likely to be made within the 

 next fifty years the astronomer will have at his 

 disposal three or four times as much light as we 

 are now able to command. The smaller stars 

 will be brought within the range of spectroscopic 

 study, and more subtle details in the spectra 

 of the larger ones can be dealt with. And if 

 photographic plates are correspondingly im- 

 proved, it is difficult to say what could not be 

 done in the way of instantaneous pictures of the 

 heavenly bodies. If an impression could be ob- 

 tained in a hundredth of a second, a great part 

 of the exasperating atmospheric difficulty would 

 be evaded, since, for so short a time as that, the 

 air is often practically quiet, even when it is 

 in an extremely bad condition for visual observa- 

 tion. 



But, on the whole, increase*in the size of tele- 

 copes seems now to be less important than the 

 improvement of their optical qualities. Our 

 present object-glasses, though wonderful prod- 

 ucts of the artist's skill, are very far from ideal 

 57 



