CAVENDISH. 103 



is wont to regard Cavendish as a chemist merely. But 

 it was not only in chemical science and in a few de- 

 partments of natural philosophy that this great man had 

 thoroughly exercised himself; he was profoundly versed 

 in every branch of physics, and was a most complete 

 and accomplished mathematician. I have had access to 

 the manuscripts which he left behind him ; and it would 

 be difficult to name any subject which had not engaged 

 his close attention : all had been made the subject not 

 only of his study, but of his original investigations. 

 The two papers on Electricity which he published in 

 the * Philosophical Transactions' contain, the one of 

 1776, the first distinct statement of the difference be- 

 tween animal and common electricity ; the other, in 

 1771, twenty-seven propositions upon the action of 

 the electric fluid, treated mathematically. They are 

 grounded upon the general hypothesis that the par- 

 ticles of the fluid repel one another, and attract those 

 of other matter with a force inversely as some lesser 

 power than the cube of the distance ; and with this 

 theory the experiments which he examines are found 

 to tally perfectly. But his voluminous unpublished 

 papers show how constantly his life was devoted to 

 experimental inquiries, and analytical or geometrical 

 investigations. Beside ranging over the whole of che- 

 mical science, they relate to various branches of optics, 

 of physical and of practical astronomy of the theory 

 of mathematical and astronomical instruments of me- 

 chanical and dynamical sciences, both theoretical and 

 practical of pure mathematics in all its branches, geo- 

 metry, the integral and differential calculus, the doctrine 

 of chances and annuities. He seems in his application 

 of mathematics to physics to have disregarded elegance, 

 and even simplicity, and to have chosen always the 

 shortest and most certain path to his object. Accordingly 

 this somewhat surprises the mathematical reader; as 



when we find him using U^. (or rather-^-, for he 

 a v v 



