II2 
selves to that useful branch of experi- 
mental philosophy. 
_ It is a principle universally admitted 
by philosophers, that the power which 
we term ¢/ediric, will never operate or 
manifest itself, unless the body to be elec- 
trified, stand opposed to some conducting 
bodies, which are connected with the 
earth, Inthe conduét of electrical ex- 
periments, if a due regard be not paid 
to this principle,. the operator will find it 
Impossible to obtain the maximum of elec- 
tric power. It is, however, not a little 
wonderful, that electricians, in general, 
overlook this observation, asa matter of 
trivial importance, and that the PRIME 
CONDUCTORS of machines are con- 
structed with little or no regard to so 
leading a principle. 
I beg leave, however, to suggest, as an 
immediate corollary to the above, and as 
the most convenient practical form for 
making experiments, that prime con- 
ductors of electrical machines ought tobe 
constructed far, and not in the cy/izdri- 
éaé form, as at present. 
To give acomplete idea cf my plan, 
to any that may be disposed to adopt it, 
i wiil deseribe a prime condu€tor, with 
its Necessary appendages, belonging to a 
machine, constructed by myself, with due 
regard to the preceding principle. My 
glass exciter was but ten or twelve inches 
indiameter, yet the length and strength 
of the spark, with the conduétor thus 
improved, were the greatest I ever wit- 
nessed.—In making such a conduétor, 
cavered a common deal board, three or 
four feet in length with tin foil, pointed 
at the end with a row of needles; this 
board, #0 covered, formed my prime con- 
duétor. I then ‘covered, with tin foil, 
two other boards of egual» dimensions 
with the former; for the purpofe of op- 
posing them to the prime conduétor, 
avove and below it. One of these boards 
f suspended from the ceiling by a chain, 
which passing over a pully, conneéted the 
board with the wall of the room; the 
other board, by two'perforations, -I made 
to pass down the glass legs of the prime 
conductor, resting tt on the bases of 
those legs, and conneéting it by a chain 
with the ground. This, when com- 
pleted, my prime cenductor, with its 
auxiliary plates,-or opposers, formed three 
p2rall¢gl boards ;, the conductor itself being 
in the middle, and having boards opposed 
to it above and below, which enabled it 
to Feceive the electric power, in the 
greatest possible degree of capacity. 
On this construction, a spark taken by 
Eleétrical Machines.—Progrefs of the Arts. 
[ March 
a person standing on the‘floor, discharged 
a double and large plate of air, ite 
length, from eight to twelve inches, and 
its strength accumulated to a degree, 
scarcely to be borne by the operator. _ 
When the room was darkened, and 
the machine put in motion, the. light 
visibly passed up and down the lmks of 
the two chains, which conneéted the 
boards with the ground, thereby evinc- 
ing the utility of their application. A. 
variety of amusing and new phenomena, 
resulted from this construction, and seve- 
ral important principles of the eleétric 
power were strikingly exemplified. It 
may also be added, that this form of a 
prime conduétor is not only more conve- 
nient to the operator, than the old form, 
but it may be construéted at much less 
expence. 
Perhaps, some of your readers may 
further improve upon the preceding hint. 
Iam, Sir, your’s, &c. 
London, Fan. 30. A. D. 
re 
To the Condultor of the Monthly Magazine. 
SIR, 
I W AS obliged by your inserting, in the 
last Magazine, my communication re- 
lative to the LITERARY FUND. Thofe 
hints were confined to the distresses of 
men of letters. The following cursory 
remarks relate to the means of facilitating 
the progress of the arts and sciences; 
and if you find them suited to the genius’ 
of your Repository, you will, perhaps, 
Insert them. ° 
Having occasionally employed’ my 
leisure hours in looking into poor houses, 
prisons, public schools, and the like, I’ 
have been struck with the numerous de- 
feéts which exist in them. 
I was disposed, a few weeks ago, to 
see how it fared with the arTs. I ac- 
cordingly went to Somerset-house, to 
hear Mr. Barry deliver his Leétures on 
Painting. It is unnecessary to lay before 
you the professor’s observations on the 
art; but I will just hint to you, that 
each leéture was closed with a Jamenta- 
tion, which, if just, impeaches the ge- 
nerosity of the English nation. 
Mr. Barry’s ground of complaint was*, 
that there exists no public repository, to 
which students might resort, and in 
which they might study and copy, at their 
iii We Dials vel 91 oe 
* Mr. Barry has repeated this lamentation 
for these twenty years past, as appears from a 
volume on the Arts, published by him about’ 
twenty years ago, y a 
leisure, 
