144 Caroline Lucretia HerscheL [1822. 



pages of problems, oblique plain triangles, right-angled 

 spherical triangles, how to find the logarithm of a num- 

 ber given, and theorems for making tables of motion. 

 With this slender store of attainment she accomplished 

 a vast amount of valuable work, besides the regular 

 duties of assistant to so indefatigable an observer as 

 Sir William Herschel. He was invariably accustomed 

 to carry on his telescopic observations till daybreak, 

 circumstances permitting, without any regard to season ; 

 it was the business of his assistant to note the clocks 

 and to write down the observations from his dicta- 

 tion as they were made. Subsequently she assisted in 

 the laborious numerical calculations and reductions, so 

 that it was only during his absences from home, or 

 when any other interruption of his regular course of 

 observation occurred, that she was able to devote 

 herself to the Newtonian sweeper, which she used 

 to such good purpose. Besides the eight comets 

 discovered by her, she detected several remarkable 

 nebulae and clusters of stars previously unnoticed, 

 especially the superb nebula known as No. 1, 

 Class V., in Sir William Herschel's Catalogue. Long 

 practice taught her to make light of her work. 

 "An observer at your twenty-foot when sweeping/' 

 she wrote many years after, " wants nothing but 

 a being who can and will execute his commands 

 with th0 quickness of lightning ; for you will have 

 seen that in many sweeps six or twice six objects 



