308 pRonvcTiots ot electricity by friction^. 



in a given time. The fact, therefore, which is expressed ia 

 the first proposition, and which is fully established in prac- 

 tice, is in all respects consistent with the proposed theory. 

 Necessity of Now, from what has been said, it follows^ that, if the rub- 



the rubber's ^^p^ ^^ ^^^ freely communicate with the Earth, it must be- 

 commuiM- _ "^ , , ^ 



eating with Come negatively electrified, by the same operation, that 

 tlie Earth. gives a positive charge to the prime conductor; and conse- 

 quently less and less qualified, as the experiment proceeds, 

 to produce a positive charge on the plate or cylinder. We 

 therefore, perceive a sufficient reason, why, if the rubber be 

 insulated, the prime conductor acquires only a low excite- 

 tuentj and the action of the machine ceases altogether in a 

 very short time. 

 Allihepheno- The reasonings I have employed apply particularly to 

 We on thh'"^'^' *^^ electrical machine in its present improved state. The 

 principle. principles of my argument may, however, be extended to 



every experiment, in which excitement is produced by fric- 

 tion, and will, if I have not entirely deceived myself, afford 

 a perfect and satisfactory explanation of the phenomena. I 

 would, therefore, draw ray observations on this subject to a 

 conclusion, by stating, that the contact and separation of 

 dissimilar bodies, which have been demonstrated to be a 

 cause of electrical excitement, must operate whenever we 

 employ friction, and that it is capable of producing the 

 principal phenomena, which are excited by friction. This 

 appears to me to form as strong a degree of evidence in fa- 

 ' vour of a doctrine, as philosophy need require. 



A step towards The facts, sir, to which I have called your attention, do 

 tion of elec-^' ^'^'^ immediately point to any bold and extensive views of 

 trical pheno- nature; but they enable us to proceed one step towards a 

 perfect generalization of electrical phenomena; and it is 

 impossible for us to say, to what interestiiig truths they may 

 ultimately lead. It will, no doubt, be admitted by every 

 one, that an important advantage will have been gained, 

 when we are able to reduce all the means of exciting elec- 

 tricity to one head; as we shall then be better qualified than 

 we are atpresent, to investigate the relations, which unques- 

 tionably prevail, between the first principles of heat, light, 

 magnetism, and electricity. 

 Kxf itemeni of The excitement of the galvanic.battery is a subject yet in- 



« J. volved 



