\ 
1808.]  Aucount of the late Thunder-storm in Somersetshire. 
The stones measured from ten to thirteen 
inches about; some oval, others pricked, 
and some flat.—Philos, Trans. No. 229. 
Superior, however, to either of these, 
both in grandeur and extent, was the So- 
mersetshire storm of the 15th of July, 
1808 ; some general idea of which, with 
some of the very interesting particulars, 
- J am desired to communicate through 
the medium of the Monthly Magazine. 
Standing, as I did, about two miles 
from the eastern limits of the most pow- 
erful part of this memorable tempest, I 
had full opportunity of viewing and con- 
templating those magnificent volumes of 
electric fire which exhibited themselves 
every three or four seconds, and of listen- 
ing to those solemn reverberations of 
sound which accompanied them, without 
experiencing any of their baleful effects; 
and could make my observations on the 
sublime spectacle in safety. I perceived 
that, as the storm approached the neigh- 
bourhood of Frome, the smailer detached 
clouds frequenily rushed with unusual ra- 
pidity towards that part of the main 
cloud where an eruption had taken place, 
in exact conformity to the known doc- 
trine in eletricity (which may be termed 
thunder and lightning in miniature), that 
when bodies possess such’ portion only of 
electric matter as they can retain by non- 
attraction, they are in an unelectrified 
state. When the equilibrium of electric 
matter is disturbed, and they acquire an 
additional quantity from other bodies, 
they are electrified positively, or plus; and 
and when they lose their natural share, 
they are said to be electrified negatively, 
or minus: so that when bodies are elec- 
‘tified thus differently, they will attract 
each other until they mutually give and 
‘receive equal quantities of the electric 
fluid, and the equilibrium is restored. 
Thus, in the instance before mentioned, 
when any part of the main eloud had 
parted with a portion of its fluid by eru 
tion, the neighbouring clouds rushed for- 
wards to communicate their contents, 
‘that such equilibrium might again be re- 
stored.* The effect produced by the 
————— 
'-* This eyuilibrium of electric matter 
ms to denote the purest and most salutary 
State of our atmosphere. A physician of 
eminence, in hig Monthly Report of Diseases, 
‘remarks, that ‘* Fevers abounded less in the 
month next after this storm, than they did 
“in the month preceding, in proportion of 
“three to twelve; in cuns: quence, no doubt 
(he says), of a mitization of heat, and other. 
atmospheric amelioration.”—Monthly Mag. 
Aug. and Sept, 1808. 
303 
ignited electrical matter causing a vacuum 
in its passage, and the contiguous air 
collapsing suddenly, and with violence, 
are therefore the immediate causes of 
thunder. 
In less than two hours time, this thun« 
der-cloud had encreased to a vast magni« 
tude, extending its bulk over the horizon 
from S.E. to N.W. and its height or 
thickness I found, by observation and 
computation, to be nearly a mile. Its 
progress, as I have since found, was 
nearly seventy miles, and its average 
breadth about eight miles; so that the 
space of earth over which it was sus- 
pended, in its progress, was not less than 
550 square miles, 
The lightning exhibited flashes vastly 
extended, and highly vivid, and which 
darted in every direction, as the electric 
attraction invited. The thunder was one 
incessant roar. The following morning 
was fraught with intelligence of devasta- 
tions eaused by a tremendous shower of 
hail, which fell at the time, such as the 
oldest man living in our country had not 
remembered. ‘The hail-stones were exe 
traordinary, both in size and form; some 
small as a pea, others larger than an 
orange: some round, others broad, flat, 
polygonic, angular, or crenated, having 
cores of different density from the exe 
treme parts. The hail-water was of a 
blackish hue, and of an unpleasant phose 
phoric taste. 
Various and contradietory relations of 
the facts, made me desirous of ascere 
taining them; and tothis end I dispatch 
ed circular letters to my distant friends 
within the limits of the storm, request- 
ing the favour of their reply to certain 
questions that I judged applicable to the 
subject: such as the time when the 
storm began, in their respective situa- 
tions; the length of its coutinuance; the 
point from which the wind blew at the 
time; the quarter from which the storm 
appeared to come, and the point to 
which it tended at its departure ; the mee 
dium and extreme sizes of the hail~ 
stones; the time of intermissions between 
the flashes of lightning; the general ef- 
fects of the storm on vegetables, ani- 
mals, buildings, &c. &c.—To these en- 
quiries I have been favoured with satis- 
factory answers from persons of great 
respectability, who were witnesses of the 
phenomenon, and its effects. 
LT 
From this we perceive, that even storms 
of lightning (alarming as they are) are 
amongst the ultimately beneficial economics 
of Nature. 
In 
