33o A Short History of Astronomy [CH. xii. 



receive a large number of visitors who came to Slough out 

 of curiosity or genuine scientific interest to see the great 

 man and his wonderful telescopes. In 1801 he went to 

 Paris, where he made Laplace's acquaintance and also saw 

 Napoleon, whose astronomical knowledge he rated much 

 below that of George III., while "his general air was 

 something like affecting to know more than he did know." 



In the spring of 1807 he had a serious illness ; and from 

 that time onwards his health remained delicate, and a 

 larger proportion of his time was in consequence given to 

 indoor work. The last of the great series of papers 

 presented to the Royal Society appeared in 1818, when he 

 was almost 80, though three years later he communicated 

 a list of double stars to the newly founded Royal Astro- 

 nomical Society. His last observation was taken almost at 

 the same time, and he died rather more than a year after- 

 wards (August 2ist, 1822), when he was nearly 84. 



He left one son, John, who became an astronomer only 

 less distinguished than his father (chapter xin., 306-8). 

 Caroline Herschel after her beloved brother's death returned 

 to Hanover, chiefly to be near other members of her family ; 

 here she executed one important piece of work by cataloguing 

 in a convenient form her brother's lists of nebulae, and for 

 the remaining 26 years of her long life her chief interest 

 seems to have been in the prosperous astronomical career 

 of her nephew John. 



257. The incidental references to Herschel's work that 

 have been made in describing his career have shewn him 

 chiefly as the constructor of giant telescopes far surpassing 

 in power any that had hitherto been used, and as the 

 diligent and careful observer of whatever could be seen 

 with them in the skies. Sun and moon, planets and fixed 

 stars, were all passed in review, and their peculiarities noted 

 and described. But this merely descriptive work was in 

 Herschel's eyes for the most part means to an end, for, as 

 he said in 1811, "a knowledge of the construction of the 

 heavens has always been the ultimate object of my 

 observations." 



Astronomy had for many centuries been concerned almost 

 wholly with the positions of the various heavenly bodies 

 on the celestial sphere, that is with their directions. 



