n could have been taken, with any chance of
safety, from an electrical kite-string; and by reference to the comparison
hereafter to be made (371.), it will be seen that for common electricity to
have produced the effect, the quantity must have been awfully great, and
apparently far more than could have been conducted to the earth by a gilt
thread, and at the same time only have produced the "usual shocks."

340. That the electricity was apparently not analogous to voltaic
electricity is evident, for the "usual shocks" only were produced, and
nothing like the terrible sensation due to a voltaic battery, even when it
has a tension so feeble as not to strike through the eighth of an inch of
air.

341. It seems just possible that the air which was passing by the kite and
string, being in an electrical state sufficient to produce the "usual
shocks" only, could still, when the electricity was drawn off below, renew
the charge, and so continue the current. The string was 1500 feet long, and
contained two double threads. But when the enormous quantity which must
have been thus collected is considered (371. 376.), the explanation seems
very doubtful. I charged a voltaic battery of twenty pairs of plates four
inches square with double coppers very strongly, insulated it, connected
its positive extremity with the discharging train (292.), and its negative
pole with an apparatus like that of Mr. Barry, communicating by a wire
inserted three inches into the wet soil of the ground. This battery thus
arranged produced feeble decomposing effects, as nearly as I could judge
answering the description Mr. Barry has given. Its intensity was, of
course, far lower than the electricity of the kite-string, but the supply
of quantity from the discharging train was unlimited. It gave no shocks to
compare with the "usual shocks" of a kite-string.

342. Mr. Barry's experiment is a very important one to repeat and verify.
If confirmed, it will be, as far as I am aware, the first recorded case of
true electro-chemical decomposition of water by common electricity, and it
will supply a form of electrical current, which, both in quantity and
intensity, is exactly intermediate with those of the common electrical
machine and the voltaic pile.

* * * * *

III. _Magneto-Electricity._

343. _Tension_.--The attractions and repulsions due to the tension of
ordinary electricity have been well observed with that evolved by
m