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VIII. On the magnetic Phenomena produced by Electricity; in 
a Letter from Sir H. Davy, Bart. F.R.S. to W.H. Wox- 
Laston, M.D. P.R.S.* 
My DEAR Sir,— Lux similarity of the laws of electrical and 
magnetic attraction has often impressed philosophers ; and many 
years ago, in the progress of the discoveries made with the Vol- 
taic pile, some inquirers (particularly M. Rittert+) attempted to 
establish the existence of an identity or intimate relation between 
these two powers; but their views being generally obscure, or 
their experiments inaccurate, they were neglected: the chemical 
and electrical phenomena exhibited by the wonderful combination 
of Volta, at that time almost entirely absorbed the attention of 
scientific men; and the discovery of the fact of the true con- 
nexion between electricity and magnetism, seems to have been re- 
served for M. Cérsted, and for the present year. 
This discovery, from its importance and unexpected nature, 
cannot fail to awaken a strong interest in the scientific world ; 
and it opens a new field of inquiry, into which many experimen- 
ters will undoubtedly enter: and where there are so many ob- 
jects of research obvious, it is scarcely possible that similar facts 
should not be observed by different persons. The progress of 
science is, however, always promoted by a speedy publication of 
experiments ; hence, though it is probable that the phenomena 
which I have observed may have been discovered before, or at the 
same time, in-other parts of Europe, yet I shall not hesitate to 
communicate them to you, and through you to the Royal Society. 
* From the Transactions of the Royal Society, for 1821, Part [. 
+ M. Ritter asserted that a needle composed of silver and zinc arranged 
itself in the magnetic meridian, and was slightly attracted and repelled by 
the poles of a magnet ; and that a metallic wire, after being exposed in the 
Voltaic circuit, took a direction N.E. and S.E. His ideas are so obscure, 
that it is often difficult to understand them; but he seems to have had some 
vague notion that electrical combinations, when not exhibiting their elec- 
trical tension, were in a magnetic state, and that there was a kind of electro- 
netic meridian depending upon the electricity of the earth_—See Ann. 
de Chimie, t. \xiv. p. 80. Since this letter has been written, D. Marcet has 
been so good as to send me from Genoa, some pages of Aldini on Galvanism, 
and of Izarn’s Manual of Galvanism, published at Paris more than sixteen 
years ago. M. Mojon, senior, of Genoa, is quoted in these pages as having 
yendered a steel needle magnetic, by placing it in a Voltaic circuit for a 
great length of time. This, however, seems to have been dependent merely 
upon its place in the magnetic meridian, or upon an accidental curvature of 
it; but M. Romagnesi, of Trente, is stated to have discovered that the pile 
of Volta caused a declination of the needle; the details are not given, but 
if the general statement be correct, the author could not have observed the 
same fact as M. CErsted, but merely supposed that the needle had its mag- 
netic poles altered after being placed in the Voltaic circuit as a part of the 
electrical combination, 
F2 I found, 
