Biographical Memoir of Henry Cavendish. 217 



admitted by him, nor could any sophism pass unperceived. 

 His character, in this respect, was such, that his friends hasten- 

 ed to lay their researches before him, assured that if he ap- 

 proved of them, no one could find occasion to contradict them. 

 He treated himself more severely than any other ; and thus he 

 was enabled to give his works such a degree of perfection, that 

 even now nothing can be added to them, nor can any alteration 

 }yQ made in them, although the first of them appeared more than 

 forty years ago, and although the science to which they refer 

 has in that interval undergone a complete revolution. They 

 are, perhaps, the only scientific productions in existence that can 

 boast of such a merit. This severity, introduced by Mr Caven- 

 dish into chemical inquiries, was as beneficial to the science as 

 his discoveries themselves ; for it is to his method that we are, 

 in a great measure, indebted for the discoveries which were 

 made by others. Until about the middle of the eighteenth cen- 

 tury, chemistry seemed to have become an asylum for the gra- 

 tuitous suppositions and baseless theories which Newton had 

 expelled from physics. Cavendish and Bergman pursued them 

 thither ; they cleared that Augean stable, still overspread with 

 the rubbish of the hermetical philosophy. Since their time no 

 one has dared to operate but on determinate quantities, and by 

 keeping a strict account of all the kinds of products ; and it is 

 this which forms the distinctive character of the modern chemi- 

 stry, much more than its theories, which, beautiful as they 

 appear to us, will not perhaps be unimpeachable, should the 

 substances, which have hitherto baffled our research, be one 

 day mastered. Mr Cavendish owed this strictness to a profound 

 study of geometry, of which he has also made direct applica- 

 tions, sometimes as happy as his chemical researches. Such, 

 in particular, is his determination of the mean density, or, 

 which comes to the same thing, of the total weight of the 

 globe * ; an idea which at first had something frightful in it, 

 but which, nevertheless, reduces itself to a simple law of me- 

 chanics. Archimedes asked a point of support for moving the 

 earth, but Mr Cavendish required none for weighing it. 



Another member of the Royal Society, who died some time 

 previously, Mr Mitchell, conceived the means of accomplishing 



• Phil, Trans. 1798, Part II. p. 469. 



