262 PHYSICAL SCIENCE 



times, regarded with fear and consternation, and 

 considered as direct signs of Divine wrath. 



Yet the oldest of the sciences is also, in some 

 respects, if not the newest, at any rate among the 

 youngest of the fraternity; for in its recent growth, 

 its spirit of adventure, its capacity of immediate 

 development, it shows all the characteristics of 

 sturdy youth. 



In the history of the different branches of 

 physical science, it is constantly found that 

 periods of great activity and advancing know- 

 ledge alternate with periods when, owing to the 

 exhaustion of the possibilities of the apparatus 

 available or of the methods of research employed, 

 progress seems almost to cease. 



Seventy years ago astronomy appeared to be 

 sinking into one of these periods of comparative 

 stagnation. The power of the telescope seemed 

 almost to have reached a limit, for although 

 improved and larger instruments were being 

 produced continually, the revelations they made 

 were apparently unworthy of the knowledge and 

 skill lavished on their manufacture. It was not 

 more elaborate instruments, but new methods of 

 research that were wanting. 



But even while the older astronomy was flag- 

 ging, the new method had appeared, and was only 

 waiting for development in its apparatus to carry 

 forward the torch of learning into untrodden 

 paths, and even to rival the discoveries of Adams 

 and Leverrier, who had stirred so profoundly the 

 imagination of their generation. 



The new science of astro-physics dates from 

 the application of the spectroscope to astronomical 



