1820.] Fratiklin's Theory of Electricity. 443 



induced to give a plate of it representing the ray exactly as it 

 was observed at the positive conductor. My colleague, 

 M. Paets von Troostwijk, who, at that time, used frequently to 

 favour me by attending at these experiments made with the 

 large Teylerian machine, will be able to recollect that one even- 

 ing, when the action of the machine was particularly strong, we 

 endeavoured to make as correct a drawing as possible of this 

 spark, and that we unanimously made choice of the sketch which 

 we judged most faithful. Plate CX represents the spark one-third 

 of its natural size. 



Shortly after the appearance of the first volume of my electri- 

 cal experiments made with the large Teylerian machine, I 

 visited Paris in June, 1785, and distributed copies of the work 

 to some members of the Royal Academy of Sciences, viz. to 

 MM. Le Roy, Brissons, Lavoisier, BerthoUet, Monge, and Van 

 der Monde. After having seen the drawing of the spark with its 

 ramifications, they all agreed with me that, considering the visi- 

 ble direction of the sparks produced by the large machine, it was 

 incontestibly proved that, in conformity with Franklin's theory, 

 a single electric fluid proceeds from the positive conductor, and. 

 passes into the next conductor, which receives it ; while, on the 

 contrary, when the machine is made to act negatively, the elec- 

 tric fluid proceeds in a contrary direction from the adjoining 

 conductor, and passes into that which is negatively electrified. 



The celebrated Franklin being at that time still at Passy, near 

 Paris, but on the point of returning to America, many of the 

 aforesaid members of the Academy eagerly encouraged me to 

 present to that great genius, to whom this branch of physics 

 was so greatly indebted, the first fruits of my electrical experi- 

 ments with the large Teylerian machine. M. Le Roy accompa- 

 nied me to Passy, where we were the last of those who were 

 introduced to Franklin previous to his return to America. 



On being first announced, we perceived that it was his 

 intention, after having granted us a short interview, to excuse 

 himself on account of his approaching departure. But per- 

 ceiving that the experiments, of which I offered him the 

 descriptions, were very important with regard to that branch of 

 physics in which he himself had formerly made so many success- 

 ful researches, this venerable old man, whose presence inspired 

 me with a profound respect, made me sit down beside him, and 

 begged me to communicate and point out to him whatever I 

 judged most hkely to throw a light upon this science. After 

 attentively considering the figure of the spark, and the direction 

 of its lateral branches, he inquired of me very seriously whether 

 one might be satisfied that the drawing represented nothing but 

 what had been actually observed ? When I had given him assu- 

 rances on this head that seemed to remove his doubts, he said, 

 *' This then proves my theory of a simple electric fluid, and it is 

 now high time to reject the theory of two sorts of fluids." 



