M. Oersted on Magnefiim and Gaivankm, 167 
Whatever method of doubling the image the practical as- 
tronomer may adopt, after a careful examination of all those 
that have hitherto been proposed, we beg to press upon his 
attention the contrivance which we have described for bring- 
ing the images in contact. It requires no additional lens or 
speculum, and gives equally distinct images at every part of the 
scale. 
Edii^buegh, ) 
Nov. 
Aet. XXVII. — Account of the Discoveries of M. Oersted^ re- 
specting the Connection between Magnetism and Galvanism^ 
and the subsequent Researches qf Sir Humphry Davy^ Bart 
M, Ampere, and M. Biot*. 
The connection between Electricity and Magnetism has 
long been a matter of probable conjecture, not merely from the 
influence of lightning and artificial electrical discharges on the 
magnetic needle, but also from the local coincidence between the 
beams of that decidedly electrical phenomenon, the Aurora Bo- 
realis, and the principal magnetic axis of the earth. No deci- 
sive experiments, however, were made to establish their identi- 
ty ; and if we except a very curious result, obtained by a mem- 
ber of the Royal Society of Edinburgh, of which we cannot at 
present obtain the particulars, the sole merit of having effected 
this discovery is owing to M. Oersted, Secretary to the Royal 
Society of Copenhagen. 
Some years ago an attempt was made by several philosophers, 
to influence the magnetic needle, by placing it in the open gal- 
Tanic circuit, but no effect was perceptible and it occurred to 
Mr Oersted to make the experiment when the galvanic circle 
was complete. He immediately found that the magnetic needle 
* This paper has been drawn up from three articles in the Journal de Physique, 
tom. xci. p. 72. and other materials, kindly communicated to us by M. Blainville, 
before they appeared in his own excellent Jdurnat. Sir Humphry Davy’s paper 
has been read at the Royal Society ; and we are fortunate in having obtained.® 
eorrect account of its leading results.— D. B, 
