155 
connected two bells with his apparatus, which gave him notice by ringing, 
whenever his rod was electrified. 
Jupiter, the supreme god of the ancients, being thus disarmed of his 
terrors, the subject was taken up with the utmost philosophical ardour. 
Thunder storms, says Beccaria, generally happen when there is little or 
no wind, and their first appearance is marked by one dense cloud, or more, 
increasing very fast in size, and rising into the higher regions of the air; the 
lower surface black, and nearly level, but the upper finely arched, and well 
defined. Many of these clouds seem frequently piled one upon another, all 
arched in the same manner; and they keep continually uniting, swelling, and 
extending the arches. 
At the time of the rising of this cloud, the atmosphere is generally full of 
a great number of separate clouds, motionless, and of odd and whimsical 
shapes. All these, upon the appearance of the thunder cloud, draw towards 
it, and become more uniform in their shapes as they approach, till coming 
very near the thunder cloud, their limbs mutually stretch towards one ano¬ 
ther; they immediately coalesce, and together make one uniform mass. 
When the thunder cloud is grown to a great size, its lower surface is 
often ragged, particular parts being detached towards the earth, but still con¬ 
nected with the rest. Sometimes the lower surface swells into various lame 
o 
protuberances, bending uniformly towards the earth. When the eye is 
under the thunder cloud, after it is grown larger, and well formed, it is seen 
to sink lower, and to darken prodigiously, at the same time that a number of 
small detached clouds (the source of which can never be perceived) are 
seen in a rapid motion, driving about in a very uncertain direction under it. 
A cloud in a thunder storm may be considered as a great conductor, 
actually insulated and electrified ;* and it may be supposed to have the same 
effect upon those non-electrics which it meets with in its course, as our 
common conductors have upon those which are presented to them. If a 
cloud of this kind meets with another which is not electrified, or less so than 
itself, the electric matter flies off from all parts towards this cloud; hence 
proceed flashes of lightning, and the formidable report of thunder. 
* Professor Saussure, when passing the Alps, meeting with thunder-clouds, found his body imme¬ 
diately replete with the electric fluid, and having insulated himself by means of a stool with glass feet, 
his companion Mons. Galabert observed his hair to stand an end, and sparks were drawn from him 
with a crackling noise, as in those electrified by art. This is another corroboration of the truth of Dr. 
Franklin’s great discovery. 
