has computed the mean density of the 

 Earth to be 



III 

 CONTRIBUTIONS TO ASTRONOMY 



THE studies pursued by John Michell in 

 this branch of science were marked by 

 his characteristic originality and insight. 

 Not only was he an actual observer of 

 the heavens, working with a reflecting 

 telescope of his own construction, but in 

 his theoretical discussion of stellar phe- 

 nomena he introduced the mathematical 

 computation of probabilities, and showed 

 sometimes a remarkable prescience that 

 seems to anticipate the discoveries of 

 more recent times. Reference has already 

 been made to the family tradition that 

 Michell gave William Herschel his first 

 lessons in Astronomy and taught him the 

 art of making reflectors. Before entering 



1 Boys, "On the Newtonian Constant of Gravi- 

 tation,*^//. Tram. vol. 1 86(1 896) ; seealsoPrw. Roy. 

 Soc. vol. 46, p. 253 ; Proc. Roy. Imtit. vol. xiv (i 894). 



9' 



