| I found the Bells rang sometimes when there was no Lightning or Thunder,
but only a dark Cloud over the Rod; that sometimes after a Flash of
Lightning they would suddenly stop; and at other times, when they had
not rang before, they would, after a Flash, suddenly begin to ring;
that the Electricity was sometimes very faint, so that when a small
Spark was obtained, another could not be got for sometime after; at
other times the Sparks would follow extremely quick, and once I had
a continual Stream from Bell to Bell, the size of a Crow-Quill. Even
during the same Gust there were considerable variations. |
| What quantity of lightning a high, pointed rod, well communicating with the
earth, may be expected to discharge from the clouds silently in a short
time, is yet unknown; but I reason from a particular fact to think
it may at some times be very great. In Philadelphia I had such a rod
fixed to the top of my chimney, and extending about nine feet above
it. From the foot of this rod, a wire (the thickness of a goose-quill)
came through a covered glass tube in the roof, and down through the
well of the staircase; the lower end connected with the iron spear
of a pump. On the staircase opposite too my chamber door, the wire
was divided; the ends separated about six inches, a little bell on
each end; and between the bells a little brass ball, suspended by a
silk thread, to play between and strike the bells when clouds passed
with electricity in them. After having frequently drawn sparks and
charged bottles from the bell of the upper wire, I was one night awaked
by loud cracks on the staircase. Starting up and opening
the door, I perceived that the brass ball, instead of vibrating as
usual between the bells, was repelled and kept at a distance from both;
while the fire passed, sometimes in very large, quick cracks from bell
to bell, and sometimes in a continued, dense, white stream, seemingly
as large as my finger, whereby the whole staircase was inlightened
[sic] as with sunshine, so that one might see to pick up a pin. And
from the apparent quantity thus discharged, I cannot but conceive that
a number of such conductors must considerably lessen that of any approaching
cloud, before it comes so near as to deliver its contents in a general
stroke; an effect not to be expected from bars unpointed, if the above
experiment with the blunt end of the wire is deemed pertinent to the
case. |