The prime conductor of an electric machine, A. B. (_See Plate_
IV.) being supported about 10 inches and a half above the table by
a wax-stand, and under it erected a _pointed wire_ 7 inches and a
half high, and one-fifth of an inch thick, and tapering to a sharp
point, and communicating with the table; when the _point_ (being
uppermost) is _covered_ by the end of a finger, the conductor may be
full charged, and the electrometer c[86], will rise to the height
indicating a full charge: but the moment the point is _uncovered_,
the ball of the electrometer drops, showing the prime conductor
to be instantly discharged and nearly emptied of its electricity.
Turn the wire its _blunt_ end upwards (which represents an unpointed
bar) and no such effect follows, the electrometer remaining at its
usual height when the prime conductor is charged.
[Illustration: (of these experiments)
_Plate IV._ _Vol. I. page 388._
_Published as the Act directs, April 1, 1806, by Longman, Hurst, Rees
& Orme, Paternoster Row._]