442 M. Van Marum on [Dec. 



considered as incontestibly proved. Having, since the publica- 

 tion of that memoir in 1782, been employed in searching for 

 some completely convincing proof of the unity of the electric 

 fluid, I conceived that I had undoubtedly discovered it in the 

 ramification of the sparks proceeding from the conductor of the 

 large Teylerian machine, since the sparks were there so distinctly 

 indicated. On looking at the sparks passing between the first 

 conductor and the receiving conductor opposite, it might be 

 continually seen that all the lateral branches of the sparks directed 

 themselves towards the conductor opposite to the first conductor. 

 One percaived them very plainly (what could never be observed 

 so long as the common electrical machines had produced only 

 such sparks as were undivided or not ramified) by the direction of 

 the lateral sparks always turning themselves from the first conduc- 

 or, and tending towards the opposite one, that the spark issued 

 from the first and passed into the second conductor. 



All those who were present at these experiments made with 

 the large electrical machine, were struck with this manifest 

 direction of the electric fluid from the first towards the opposite 

 conductor ; and each time that I have had the pleasure of find- 

 ing at these experiments some philosophers conversant in elec- 

 tricity, and acquainted with the old theory of Du Fay and 

 Symmer, according to which it was pretended that the electric 

 fluid was produced not by the transition of a simple fluid from 

 one conductor to the other, but by the concurrence of two dif- 

 ferent fluids meeting in contrary directions, I have had the 

 satisfaction of hearing it generally averred that this visible 

 direction of the fluid from one conductor to the other furnished 

 the most evident proof against the theory of Du Fay and Sym- 

 mer, and in favour of that of Franklin, according to which the 

 electric phenomena are the effects of the transition of a single 

 fluid. 



I repeated at different times, for those who considered the 

 importance of this phenomenon as a decisive proof in favour of 

 Franklin's system, the experiment of the spark branching off to 

 the other conductor, which is connected with the parts of the 

 machine producing the friction, and named, conformably to 

 Franklin's system, the negative conductor. Although the con- 

 struction of the apparatus is such as to prevent the electricity of 

 the negative conductor by any means equalling that of the posi- 

 tive one, nevertheless, when the weather was favourable, the 

 spark formed ramifications which were constantly observed to take 

 a direction opposite to that of the positive conductor; for 

 instead of proceeding from the electrified conductor, as was the 

 case with the positive conductor, one perceived, by the direc- 

 tion of the branches towards the conductor united to the 

 cushions that the sparks proceeded from the next conductor, 

 and passed to that which was in a state of electricity. 



This phenomenon being so striking and interesting, I was 



