sion_, and is very slight for
a single cell; but in a series of cells it becomes noticeable in other
ways. Thus when the terminals of a single cell are taken in the hands,
no effect is perceived: if, however, the terminals of a battery
consisting of forty or fifty cells be thus taken, a decided shock is
felt, not to be compared though with the shock that would be felt from
the discharge of a very small Leyden jar. The shock from several hundred
cells would be very dangerous.

It was formerly doubted that the electricity would pass between the
terminals of a battery without actual contact of the terminals. Gassiot
first showed that the spark would jump between the wires of a battery of
a large number of cells before actual contact was made. Latterly Mr. De
La Rue has been measuring the distance across which the spark would
jump, using a battery of a large number of cells.

I give his table as taken from the "Proceedings of the Royal Society:"--

Cells. Striking distance.

600 .0033 inch.

1,200 .0130 "

1,800 .0345 "

2,400 .0535 "

This table shows that the striking distance is very nearly as the square
of the number of cells. Thus, with 600 cells the spark jumped .0033
inch; and with double the number of cells, 1,200, the spark jumped .0130
inch, or within .0002 of an inch as far as four times the first
distance.

This leads one to ask how big a battery would be needed to give a spark
of any given length, say like a flash of lightning. One cell would give
a spark .00000001 inch long, and a hundred thousand would give a spark
92 inches long. A million cells would give a spark 764 feet long, a
veritable flash of lightning. It is hardly probable that so many as a
million cells will ever be made into one connected battery, but it is
not improbable that a hundred thousand cells may be. De La Rue has since
completed 8,040 cells, and finds that the striking distance of that
number is 0.345 inch, a little more than one-third of an inch. He also
states that the striking distance increases faster than the above
indicated ratio, as determined by experimenting with a still larger
number of cells.

These experiments and many others show that there is no essential
difference between the so-called static and dynamic electricity. In the
one case it is developed upon a surface which has such a molecular
character that it cannot be conducted away, e