444 M. Van Marum on [Dec. 



After Volta, the celebrated Italian Professor, had conferred 

 upon me the favour of passing a few days with me in 1782, and 

 had since that time corresponded with me, I sent him in June^ 



1785, the first part of my electrical experiments as soon as the 

 work made its appearance. The packet having been a long 

 time on the road, 1 at length received an answer, dated March 8, 



1786, in which he makes the following observation on the sul>- 

 ject of the ramifying sparks of the large Teylerian machine : 



" Among the novel phenomena which you have obtained by 

 means of such a great electric power, I am particularly struck 

 by the ramifications thrown out by the spark, represented in 

 Plate III. These branches clearly mark the direction of the 

 electric fluid. As doubts had been raised with respect to the 

 direction itself, which, it was said, might be supposed different; 

 and as there has latterly appeared a sect who pretend to resus- 

 citate the two opposite electric fluids which meet together, and 

 catch fire from the shock, I had deviled some experiments that 

 might overturn these double electric torrents ; among the rest 

 was one which appeared to elucidate the matter completely ; 

 nevertheless it did not carry along with itself the evidence 

 which I find in these ramifications, which, all making an acute 

 angle towards the part where it is supposed the fluid is directed, 

 show that the parts laterally escaped still retain somewhat of the 

 movement common to the whole spark, and that consequently 

 one is not mistaken in admitting but a single current of the 

 electric fluid, and in assigning to it the direction supposed by 

 Franklin's theory. All orthodox electricians must be obhged to 

 you for having thus overturned for ever the heresy of the dua- 

 lists — the new partisans of the Du Fays, the Nollets, and the 

 Symmers." 



Shortly after my treatise had appeared, many of the most 

 intelligent philosophers, and the best acquainted with electricity, 

 wrote at the same time to communicate to me similar observa- 

 tions. At this epoch, it appeared to be a generally received 

 opinion, that after having so evidently seen in the ramifications 

 of the electric spark its simple direction from the positive conduc- 

 tor towards the opposite one, or to that from the one opposite 

 the negative conductor, it would not be possible ever to return 

 again to the old theory of Du Fay and Syramer, who have 

 fancied two electric fluids directed in opposite senses, and at the 

 moment of their union forming the spark. 



Nevertheless some later treatises on electricity have not 

 answered the expectations of Franklin, of Volta, and of the gene- 

 rality of those philosophers, who are most conversant in what- 

 ever regards the science. People are again returned to the old 

 opinion, of two different electric fluids, which, by their collision, 

 cause the electric sparks and other phenomena. It was, as far 

 as appears to me, the French philosophers who were the first to 

 levive the old system. 



