86 T AWiOR ¥ oF 
“ large boards of wood covered with tin, with the flat fides 
“‘ towards one another, and at fome inches afunder. For 
“ they found, that upon electrifying one of the boards 
“ pofitively, the other was always negative. But the dif- 
- « covery was made complete and indifputable by a perfon’s 
“ touching one of the plates with one hand, and bringing 
“‘ his other hand to the other plate; for he then received 
*¢ a fhock through his body exactly like that of the Ley- 
“ den experiment. With this plate of air, as we may call 
*¢ it, they made a variety of experiments. The two me- 
“ tal plates, being in oppolite ftates, ftrongly attracted one 
“another, and would have rufhed together if they had 
* not been kept afunder by the ftrings. Sometimes the 
“ ele€tricity of both would be difcharged by a ftrong {park 
“ between them, as when a pane of glafs burfts with too 
“ great a charge. A finger put between them promoted 
“ the difcharge, and felt the fhock. If an eminence was 
«¢ made on either of the plates the felf-difcharge would al- 
“« ways be made through it, and a pointed body fixed up- 
“< on either of them prevented their being charged at all.” 
To the foregoing relation of the experiments themfelves, 
I fhall fubjoin the conclufions drawn from them by the cu- 
rious electricians who made them, in the words of doctor 
Priefley, viz. “The fate of thefe two plates, they ” (Wz/- 
kie and /Epinus) * excellently obferve, juftly reprefents the 
“ ftate of the clouds and the earth” (and perhaps of. dif- 
ferent clouds at various heights one-over another) ‘ dur- 
“ing a thunder ftorm; the clouds being always in one 
“ ftate, and the earth in the oppofite; while the body of 
* air between them anfwers the fame purpofe as the {mall 
«¢ plate of air between the boards, or the plate of glafs be- 
* tween the two metal coatings in the Leyden experiment. 
“ The phenomenon of lightening is the burfting of the 
“ plate of air by a fpontaneous difcharge, which is always 
« made through eminencies, and the bodies through which 
“ the difcharge is made are violently fhocked.” 
As 
