PROGEES3 OF ELECTRICAL THEORY. 201 



with groat zeal, and after various conjectures was able to announce 13 

 that the electricity \vas excited at the point where the steam is subject 

 to friction in its emission. He found too that he could produce a like 

 effect by the emission of condensed air. Following out his views, he 

 was able to construct, for the Polytechnic Institution in London, a 

 " Hydro-electric Machine," of greater power than any electrical machine 

 previously made. Dr. Faraday took up the investigation as the subject 

 of the Eighteenth Series of his Researches, sent to the Royal Society 

 Jan. 26, 1842 ; and in this he illustrated, with his usual command oi 

 copious and luminous experiment?, a like view ; that the electricity is 

 produced by the friction of the particles of the water carried along by 

 the stream. And thus this is a new manifestation of that electricity, 

 which, to distinguish it from voltaic electricity, is sometimes called 

 Friction Electricity or Machine Electricity. Dr. Faraday has, however, 

 in the course of this investigation, brought to light several new electri- 

 cal relations of bodies.] 



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, atmospheres. When men's mechan- 

 ical ideas became somewhat more distinct, the motions and tendencies 

 to motion were ascribed to currents, in the same manner as the cosmi- 

 cal 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 contemporaneous 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 



Ph;i. M.I.J. Jan. 1842, dattd Dec. 9, 1841. ' Ac. Par. 1733, p. 4>V7. 



