THE ASTRONOMICAL VIEW OF NATURE. 363 



The extension and confirmation which the Newtonian 

 attraction formula had thus gained in the minds of 

 many seemed to be entirely upset by a series of dis- 

 coveries in which electrical, and subsequently magnetic, 

 phenomena played an important part. These were, the 

 discovery of galvanic electricity by Galvani in 1791 and 

 by Volta in 1800 ; of the physiological and chemical 

 effects of this form of electricity, especially by Davy 

 (1806); of the magnetic effect of moving electricity by 

 Oersted in 1820 ; of the connection of heat and elec- 

 tricity by Seebeck in 1822 ; of induction by Faraday in 

 1831 i.e., of the action of electric currents and magnets 

 in generating other electric currents or magnetic effects 

 in bodies which are moving in their neighbourhood ; and, 

 finally, of diamagnetism by Faraday in 1845. 



Many of the celebrated men with whose names the mod- 

 ern discoveries in electricity are identified, and amongst 

 them notably Davy and Faraday, were not brought up 

 in the mathematical school of the Continent, 1 in which 



36. 



Davy and 

 Faraday. 



sion suivant une loi quelconque ne 

 doit etre regarded que comme une 

 formule qui exprime un re"sultat 

 d'expeYience " (vol. i. p. 297). 



1 To these must be added the 

 name of Cavendish (1731-1810), 

 whose electrical researches, in 

 which he anticipated many of Cou- 

 lomb's results, proceeded on en- 

 tirely different lines from those of 

 the Continental school. He proved 

 in or before 1773 from the fact 

 that a small globe situated in the 

 hollow of a large electrified globe 

 and communicating with it showed 

 no signs of electricity, that electric 

 attraction and repulsion must be 

 inversely as the square of the dis- 

 tance. In his published and post- 



humous papers (edited by Max- 

 well in 1879 under the title of 

 ' The Electrical Researches of the 

 Hon. Henry Cavendish ') he anti- 

 cipated, as Maxwell has shown, 

 many later investigations of British 

 and Continental writers. He had 

 a clear notion of electrical capacity, 

 of potential and of electrical resist- 

 ance, he anticipated Ohm's law 

 i.e., the proportionality between 

 the electro-motive force and the 

 current in the same conductor. 

 He studied the properties of diel- 

 ectrics, and "not only anticipated 

 Faraday's discovery of the specific 

 inductive capacity of different sub- 

 stances, but measured its numer- 

 ical value in several substances" 



