CHAPTER II. 

 THE PROGRESS OF ELECTRICAL THEORY. 



THE cause of electrical phenomena, and the 

 mode of its operation, were naturally at first 

 spoken of in an indistinct and wavering manner. 

 It was called the electric fire, the electric fluid ; 

 its effects were attributed to virtues, effluvia, atmo- 

 spheres. When men's mechanical ideas became 

 somewhat more distinct, the motions and tenden- 

 cies to motion were ascribed to currents, in the 

 same manner as the cosmical motions had been in 

 the Cartesian system. This doctrine of currents 

 was maintained by Nollet, who ascribed all the 

 phenomena of electrized bodies to the contempora- 

 neous afflux and efflux of electrical matter. It was 

 an important step towards sound theory, to get 

 rid of this notion of moving fluids, and to consider 

 attraction and repulsion as statical forces ; and this 

 appears to have been done by others about the 

 same time. Dufay 1 considered that he had proved 

 the existence of two electricities, the vitreous and 

 the resinous, and conceived each of these to be a 

 fluid which repelled its own parts and attracted 

 those of the other : this is, in fact, the outline of 

 the theory which recently has been considered as 

 the best established ; but from various causes it 

 1 Ac. Par. 1733, p. 467. 



