produced by Electricity. 45 
I attached small longitudinal portions of wires of platinum, 
silver, tin, iron, and steel, in transverse directions, to a wire of 
platinum that was placed in the circuit of the same battery. 
The steel and the iron wire immediately acquired poles in the 
same manner as in the last experiment ; the other wires seemed 
to have no effect, except in acting merely as parts of the elec- 
trical circuit; the steel retained its magnetism as powerfully af- 
ter the circuit was broken as before; the iron wire immediately 
lost a part of its polarity, and in a very short time the whole 
of it. 
The battery was placed in different directions as to the poles 
of the earth; but the effect was uniformly thesame. All needles 
placed transversely under the communicating wires, the positive 
end being on the right hand, had their north poles turned to- 
wards the face of the operator, and those above the wire their 
south poles; and on turning the wire round to the other side of 
the battery, it being in a longitudinal direction, and marking the 
side of the wire, the same side was always found to possess the 
same magnetism; so that in all arrangements of needles trans- 
versely round the wire, all the needles above had north and south 
poles opposite to those below, and those arranged vertically on 
one side, opposite to those arranged vertically on the other side. 
I found that contact of the steel needles was not necessary, 
and that the effect was produced instantaneously by the mere 
juxta-position of the needle in a transverse direction, and that 
through very thick plates of glass: and a needle that had been 
placed in a transverse direction to the wire merely for an instant, 
was found as powerful a magnet as one that had been long in 
communication with it. 
I placed some silver wire of =! of an inch, and some of —,, in 
different parts of the Voltaic circuit when it was completed, and 
shook some steel filings on a glass plate above them: the steel 
filings arranged themselves in right lines always at right angles 
to the axis of the wire; the effect was observed, though feebly, 
at the distance of a quarter of an inch above the thin wire, and 
the arrangement in lines was nearly to the same length on each 
side of the wire. 
I ascertained by several experiments, that the effect was pro- 
portional to the quantity of electricity passing through a given 
space, without any relation to the metal transmitting it: thus, 
the finer the wires the stronger their magnetism. 
A zinc plate of a foot long and six inches wide, arranged with 
a copper plate on each side, was connected, by a very fine wire 
of platinum, according to your method; and the plates were 
plunged an inch deep in diluted nitric acid. The wire did not 
sensibly attract fine steel filings, When they were plunged ‘hag 
. inches, 
