[ 377 3 
riments with him in relation to this matter ; to which 
he readily confented. For that purpofe I waited 
upon him one morning about the middle of June 
laft ; and the better to ascertain what was effential in 
the fads, I varied the circumftances a little from 
thofe above. 
In the middle of a paper-book of the thicknefs of 
a quire, I put a flip of tin-foil j and in another of the 
fame thicknefs I put two flips of the fame fort of foil, 
including the two middle leaves of the book between 
them. Upon ftriking the two different books, the 
effeds were anfwerable to what I expeded. In the 
firft, the leaves on each fide of the foil were pierced, 
while the foil itfelf remained unpierced ; but, at the 
fame time, I could perceive an impreflion had been 
made on each of its furfaces, at a little diflance one 
from another ; and fuch impreflions were ftill more 
viflble upon the paper, and might be traced as point- 
ing different ways. In the fecond, all the leaves of 
the book were pierced, excepting the two that were 
between the flips of foil ; and in thefe two, inftead 
of holes, the two impreflions, in contrary diredions, 
were very viflble. 
I have lately got an eledrical apparatus of my own, 
formed on the model of that of Dr. Franklin’s, and 
have had opportunity flnce, of making frequent repe- 
titions of the experiments above-mentioned. Not- 
withftanding fome little variation in appearances, 
arifing, as in other eledrical experiments, from the 
particular ftate of the weather, the different degree 
of eledricity, or other accidental circumftances, I 
have met with nothing but what confirms me in my 
opinion of two diftind counterading powers. All 
Vol. LI. C c c the 
