262. On Eleciricily. 
current in the discharge of the Leyden jar, have been the 
subject of consideration with all practical electricians since 
the year 1760, when an account of them was first pub- 
lished. 
In the fifty first volame of the Philosophical Transactions 
(page 171 and following) Mr. Symmer has given an ac~ 
count of some experiments that led him to suspect the ex- 
istence of a double current in the discharge of the Leyden 
jar: that which appeared to bim to afford the most satis- 
factory evidence was the following. : 
He placed a slip of tinfoil in the middle of a paper book 
(the thickness of a quire), and, passing an electric charge 
through it, observed that the leaves.on each side the tinfoil 
were pierced; the tinfoil itself was not perforated, but an 
indentation was made on each of its surfaces at a little di- 
stance one from the other: these indentations were opposite 
ihe holes in the paper, and evidently pointed in opposite 
directions. 
~ In another book of the same thickness, he placed two 
slips of tinfoil with the two middle leaves of the book be- 
tween them; and he states that all the leaves of the book 
were pierced, excepting the two that were between the 
slips of tinfoil: and in these two instead of holes the two 
impressions in contrary directions were very visible. 
_ I have frequently repeated Mr. Symmer’s experiments. 
_ The result of the first is usually as he has stated, but the 
phzenomena of the second are somewhat different. When 
the two middle leaves of a paper book are inclosed between 
two slips of tinfoil, and a sufficiently powerful charge is 
passed through the book ; all the paper leaves are pierced, 
and each slip of tinfoil has. two indentations in opposite di- 
rections and in different parts of their opposite surfaces, 
Consequently, if these impressions are caused by distinct 
currents of electricity, there must be four currents to pro- 
duce this effect. 
But the phznomena., were still more remarkable when I 
introduced between the leaves of a quire of paper, six slips 
of tinfoil, each pair separated by three leaves of paper. The 
charge perforated all the paper leaves, but in different places, 
and each slip of foil had an indentation on each of its sur- 
faces, and consequently in opposite directions ; so that, ac- 
cording to Mr. Svmmer’s reasoning, there must have been 
twelve distinct electric currents. . 
The perforatious in the paper were never in a right line 
through the separate strata ; and consequently the indenta- 
tions on the opposite surfaces of each slip of tinfoil were 
at 
