IIEXRT CAVENDISH. 437 



philosophers. Blagden also made certain changes in the manuscript 

 of Cavendish's 'Experiments on Air,' and while superintending, in his 

 capacity of secretary of the Eoyal Society, the printing of the paper, 

 and of Watt's rival essay, suffered certain typographical errors to occur, 

 which involved himself and his principle in accusations of unfairness, 

 in which, however, Wilson shows that with the exception of a careless- 

 ness in correcting printer's proof, Blagden was guiltless of any wrong 

 toward Watt or of unfairness toward Lavoisier, and that to DeLuc 

 belongs the unenviable distinction of deliberately provoking the water 

 controversv, doing Cavendish and also Watt a great wrong 1>y hastily 

 deciding against the former, and filling Watt's mind with suspicions 

 that Cavendish had borrowed from Watt's letter to Priestley the views 

 which he published as his own, because he had in truth discovered them 

 for himself, and that too at an earlier date (1781) than Watt (1784:) or 

 Lavoisier (1784-86). 



Eemarkable as Cavendish's achievements in chemistry were, his 

 greatest fame as a scientist will ever be based on his researches in 

 physics ; his single experiment in dynamics would place him in the first 

 rank, and a very large part of the modem development of electrical 

 science is based upon his work in electrostatics and electro-djTiamics. 



Cavendish verified the law of inverse squares for gravitational 

 attraction, and determined the mean density of the Earth. The appa- 

 ratus, devised by the Eev. John Michell, consisted of a horizontal 

 lever six feet long, suspended by a wire forty inches in length, carrying 

 at each end a lead ball two inches in diameter. Two large masses of 

 lead (each about 317 lbs.) were placed near the ends of the lever and 

 on opposite sides, so that, their attraction would produce turning 

 moments in the same direction. The angle of rotation having been 

 measured by means of telescopes with verniers, and the torsion of the 

 suspending wire determined by observing the time of vibration of the 

 rod, the force was calculated which would have been exerted by a globe 

 of water the size of the earth on the same body on its surface, and from 

 this the density of the earth was obtained as the mean of seventeen 

 terminations to be 5.48 ± 0.38.* 



Cavendish cared more for investigation than for publication. He 

 would undertake the most laborious researches in order to clear up a 

 difficulty which none but himself could apprehend, or was even aware 

 of, and we cannot doubt that the result of his enquiries gave him a cer- 

 tain degree of satisfaction. But it did not excite in him the desire to 

 communicate the discovery to others which, in the case of ordinary men 

 of science, generally ensures the publication of their results. How 



* This work has recently been edited, together with that of Newton, 

 Bouguer and others, by Professor A. S. Mackenzie in 'The Laws of Gravitation,' 

 Scientific Memoirs, American Book Company. 



