with reference to the action of a magnet on a connecting wire, and still more silent, were it 
possible, as to the action that two of those wires exercise upon each other. 
If, on the contrary, we take, with Ampère, the action of two currents for the primordial fact, the 
three classes of phenomena will depend on one principle, one single clause. The ingenious conception 
of our associate possesses thus two of the most salient characteristics of a true laws of nature, 
simplicity and fertility. 
In all the magnetic experiments attempted before the discovery of Œrsted the earth had acted like 
a large loadstone. It was to be presumed, then, like a magnet, it would act on electrical currents. 
Experiments, however, had not justified the conjecture. Calling to his aid the electrodynamic theory 
and the talent for inventing apparatus, so brilliantly displayed by him, Ampère had the honor of 
filling the inexplicable hiatus, 
For several weeks native and foreign physicists crowded the humble study in the street 
Fossés-Saint-Victor to witness with amazement a connecting wire of platinum take a definite 
direction through the action of the terrestrial globe. 
What would Newton, Halley, Dufay, Aepinus, Franklin, and Coulomb have said if it had been announced 
to them that a day would come when, in default of a magnetic needle, navigators would be able to 
guide their vessels by observing electrical currents, electrified wires? 
The action of the earth on a conducting wire is identical in all the circumstances presented by it, 
with that which would proceed from an assemblage of currents, having its seat in the depths of the 
earth, south of Europe, and whose movements would be like the diurnal revolutions of the globe from 
west to east, Let it not be said, then, that, the laws of magnetic action being the same in the two 
theories, it is a matter of indifference which to adopt. 
Suppose the theory of Ampère true, and the earth, as a whole, inevitably a vast voltaic pile, 
creating currents moving in the direction of the diurnal revolution; and the memoir in which is 
found this magnificent result will take rank, without disadvantage, with the immortal works which 
have made of our globe a simple planet, an ellipsoid flattened at the poles, a body formerly 
incandescent in all its parts; incandescent still down in its depths, but retaining on its surface 
no appreciable trace of this original heat. 
It has been asserted that the beautiful conceptions of Ampère, of which I have just given a 
detailed analysis, were coldly received; it has been said that the French geometers and physicists 
showed themselves little inclined either to recognize or study them; that the academy, with the 
exception of one single member, swayed by its prejudices, refused for a long time to yield itself to 
unexceptionable proof. 
These charges reached the public through an eloquent and eminently honorable organ. I cannot, 
therefore, pass them by without notice.