centres being 8-85 inches apart, and he 

 thence computed the density of the 

 Earth to be 5-48 times that of water. 

 Cavendish's paper is, as usual, a model of 

 precision, lucidity and conciseness. It 

 would be difficult to mention in the 

 whole range of physics a more beautiful 

 and more important experiment 1 ." 



Since Cavendish improved Michell's 

 apparatus and first put it to the use for 

 which its designer constructed it, the 

 experiment has been repeated by several 

 observers with an approximately similar 

 result 2 . The most recent repetition is 

 that of Mr C. V. Boys. By an ingenious 

 reconstruction of apparatus and availing 

 himself of the great sensibility obtained 

 by the use of quartz-fibres instead of 

 metal wires this accomplished physicist 



1 Professor Forbes* description is contained in 

 the Sixth Dissertation of the Eighth Edition of the 

 Encyclopaedia Bntannlca^ p. 834. 



2 See Reich, Compt. rendus^ 1837, p. 697 ; Baily, 

 Mem. Astron. Soc. vol. XIV; Phil. Mag. xxi (1842), 

 p. Ill ; Cornu, Compt. rend. vol. 86, pp. 571, 699, 

 1OOI. 



9 



