fig
130. A and D are brass balls 2 inches diameter, B and C are smaller brass
balls 0.25 of an inch in diameter; the forks L and R supporting them were
of brass wire 0.2 of an inch in diameter; the space between the large and
small ball on the same fork was 5 inches, that the two places of discharge
_n_ and _o_ might be sufficiently removed from each other's influence. The
fork L was connected with a projecting cylindrical conductor, which could
be rendered positive or negative at pleasure, by an electrical machine, and
the fork R was attached to another conductor, but thrown into an
uninsulated state by connection with a discharging train (292.). The two
intervals or places of discharge _n_ and _o_ could be varied at pleasure,
their extent being measured by the occasional introduction of a diagonal
scale. It is evident, that, as the balls A and B connected with the same
conductor are always charged at once, and that discharge may take place to
either of the balls connected with the discharging train, the intervals of
discharge _n_ and _o_ may be properly compared to each other, as respects
the influence of large and small balls when charged positively and
negatively in air.

1494. When the intervals _n_ and _o_ were each made = 0.9 of an inch, and
the balls A and B inductric _positively_, the discharge was all at _n_ from
the small ball of the conductor to the large ball of the discharging train,
and mostly by positive brush, though once by a spark. When the balls A and
B were made inductric _negatively_, the discharge was still from the same
small ball, at _n_, by a constant negative brush.

1495. I diminished the intervals _n_ and _o_ to 0.6 of an inch. When A and
B were inductric _positively_, all the discharge was at _n_ as a positive
brush: when A and B were inductric _negatively_, still all the discharge
was at _n_, as a negative brush.

1496. The facility of discharge at the positive and negative small balls,
therefore, did not appear to be very different. If a difference had
existed, there were always two small balls, one in each state, that the
discharge might happen at that most favourable to the effect. The only
difference was, that one was in the inductric, and the other in the
inducteous state, but whichsoever happened for the time to be in that
state, whether positive or negative, had the advantage.

1497. To counteract this interfering influence, I made the interval _n_ =
0.79 and interval _o_ = 0.58