130 HERSCHEL AND HIS WORK 



a fruitful field for genius and perseverance to culti- 

 vate. " Its causes and laws are hid for the present 

 in almost equal obscurity," was the judgment of Dr. 

 Maskelyne, then Astronomer- Royal ; but it pointed to 

 changes among the stars, which a shrewd observer 

 would endeavour to ascertain and account for. 

 Herschel undertook the work. Availing himself of a 

 catalogue of 2884 stars published in 1723 by Flam- 

 steed, the first Astronomer-Royal, he compared the 

 heavens of his own day with the appearance they 

 presented then. He had no star charts such as 

 astronomers have since constructed, and which, when 

 compared with a revised edition a century hence, may 

 reveal much that is at present dark regarding the 

 motions and destiny of the small but beautiful home 

 of our shortlived race. He had no photographic 

 plates to expose or consult. From beginning to end 

 it was eye-labour and hand-labour with this intrepid 

 traveller among these far-away suns. So laborious 

 was the comparison that he had "many a night, in 

 the course of eleven or twelve hours of observation, 

 carefully and singly examined not less than 400 

 celestial objects, besides taking measures of angles 

 and positions of some of them with proper micro- 

 meters, and sometimes viewing a particular star for 

 half an hour together, with all the various powers of 

 his telescope." During that interval of sixty years he 

 found that stars -had been lost or had vanished, that 

 they had undergone some capital change of position or 

 magnitude, or had come into sight where they were 

 not previously seen, although " it is not easy to prove 

 a star to be newly come " into any part of the sky. 

 If a star suddenly shone out so as to attract the eyes 



