produced by Electricity. 49 
it was evident, that if the similar sides could be brought in con- 
tact, steel filings upon them would repel each other.—This was 
very easily tried with two Voltaic batteries arranged parallel to 
each other, so that the positive end of one was opposite to the 
negative end of the other: steel filings upon two wires of pla- 
tinum joining the extremities strengly repelled each other. When 
the batteries were arranged in the same order, 7, e. positive oppo- 
site to positive, they attracted each other; and wires of platinum 
(without filings) and fine steel wire (still more strongly) exhibited 
similar phenomena of attraction and repulsion under the same 
Circumstances. 
As bodies magnetized by electricity put a needle in motion, it 
was natural to infer that a magnet would put bodies magnetized 
by electricity in motion; and this I found was the case. Some 
pieces of wire of platinum, silver, and copper, were placed sepa- 
rately upon two knife edges of platinum connected with two ends 
‘of a powerful Voltaic battery, and a magnet presented to them ; 
they were all made to rol] along the knife edges, being attracted 
when the north pole of the magnet was presented, the positive 
side of the battery being on the right hand, and repelled when 
it was on the left hand; and vice versd, changing the pole of the 
magnet. Some folds of gold leaf were placed across the same 
apparatus, and the north pole of a powerful magnet held opposite 
to them; the folds approached the magnet, but did not adhere 
to it. On the south pole being presented, they receded from it. 
1 will not indulge myself by entering far into the theoretical 
part of this subject ; but a number of curious speculations can- 
not fail to present themselves to every philosophical mind, in 
consequence of the facts developed; such as whether the mag- 
netism of the earth may not be owing to its electricity, and the 
variation of the needle to the alterations in the electrical cur- 
rents of the earth in consequence of its motions, internal chemical 
changes, or its relations to solar heat; and whether the luminous 
effects of the auroras at the poles are not shown, by these new 
facts, to depend on electricity. This is evident, that if strong 
electrical currents be supposed to follow the apparent course of 
the sun, the magnetism of the earth ought to be such as it is 
found to be. 
But I will quit conjectures, to point out a simple mode of 
makivg powerful magnets, namely, by fixing bars of steel across, 
or circular pieces of steel fitted for making horse-shoe magnets, 
round the electrical conductors of buildings in elevated and ex- 
posed situations *, 
The 
* There are many facts recorded in the Philosophical Transactions which 
prove the ma mr. powers of lightning; one in particular, where a stroke 
Vol. 58, No. 279," July 182), Ci of 
