It would be to offend against a love of truth, if we proposed these views as ascertained facts. Our researches upon the magnetism of the earth have been, during too short a time, directed by the elec tromagnetic discoveries, to enable us to give a com plete theory of this subject. The great series of profound mathematical and philosophical investi gations by which Professor Hansteen, at Christiana, has confirmed and improved the theory established by Dr. Halley, shows how many difficulties are to be surmouted. The accordance of this theory with observation, seems even to exclude the possibility of a new theory; but it must be remarked that this theory is only a mathematical representation of the phenomena, and does not pretend to be a physical one. In the same way as the mathematical laws of the celestial motions were discovered by Kepler, long time before their physical laws were superfi cially guessed by Hooke, or profoundly recognised and demonstrated by Newton, so the physical laws of the magnetism of the earth may now, perhaps, be fairly conjectured, and in a future age be brought to the requisite degree of perfection. Still we hope that these views will recommend themselves to farther investigation, as they would, if proved, have the great advantage of showing an intimate connexion between an extensive series of pheno mena upon the earth and those of the universe.
Some Theoretical Considerations.
The question has during late years been often proposed, whether or not magnetism and electricity are-identical. There has been a good deal of misunder standing in the discussions on this subject. Mr. Ampere pretends that the discoverer of electro magnetism, though he had earlier -admitted the identity of these effects, has, in his first paper upon electromagnetism, denied it. We must here re mark, that the words have two aeceptations; iu one of these Professor Oersted is perhaps the most earnest supporter of this identity, in the other he is a no less decided opponent of it. His opinion is, that all effects are produced by one fundamental power, operating in different forms of action. These different forms constitute all the dissimilari ties. Thus, for instance, pressure upon the mer cury of the barometer, wind and sound, are only different forms of action of the same powers. It is easy to see that this fundamental identity extends to all mechanical effects. All pressures are pro duced by the same powers as that of air; all com munications of motion, and likewise all vibrations, owe their origin to the same expansive and attrac tive powers, by which each body fills its space, and has its parts confined within this space. This fun damental and universal identity of mechanical powers has for a long time been more or less clear ly acknowledged; but the effects which have hither to not been reduced to mechanical principles, seemed to be derived from powers so different, that the one could scarcely be deduced from the other. The discoveries which began with galvan ism, and which have principally illustrated our century, led us to see the common principles iu all these actions. Two or three years before the be ginning of the century, Ritter had, by means of the simple galvanic arrangement, pointed out and dis tinctly stated the principle of the electrochemical theory; still his ideas were not generally admitted before the discovery of the Voltaic pile had struck the mind of the experimental philosophers with more palpable facts. That heat and light are pro
duced by the union of the opposite electrical pow ers, had been acknowledged by the Swedish philo sopher Wilcke, a cotemporary of Black, but this view was far from being generally admitted. Win terl brought it forward in 1800, and was supported by Ritter and Oersted. The last investigated the subject farther, and developed some of the princi pal laws of the generation of heat by the electrical and chemical powers.* He proved that the electri cal powers are present in all cases where heat and light are generated. That magnetical effects can be produced by the same powers need not here he mentioned. As the chemical powers give rise to expansion and contraction, it appears that their na ture is not different. Thus acknowledging the fundamental and universal identity of powers, ef fects must be considered as different, when their form of action differs, and therefore magnetism, in this acceptation of the term, is far from being identical with electricity. It would likewise be er roneous to pretend that all chemical effects are produced by electricity; but the truth seems to be, that the chemical effects are produced by the same powers which, in another form of action, produce electricity. The name of electrochemical theory, given to the modern chemical system, seems, there fore, less admissible than the denomination of dy namico-chemical theory, proposed by Oersted so early as 1805. It is still true, that the common electrochemical theory deserves its name, as it does not go out of the limits of an electrical view of the subject. This theory stops throughout in generalities, and gives no account of the dispari ties of the effects. We will not pretend that a suf ficient dynamico-chemical theory has hitherto been pointed out; we must even admit that our know ledge is not ripe enough for this purpose; but we think that some laws, accounting for the dispari ties, have been pointed out in the work above quoted, upon the identity of electrical and chemical powers (viz. fundamental powers), and that the ideas therein explained deserved attentive examina tion. The dynamico-chemical theory must still remain very imperfect, until it is decided if the powers acting in magnetism, electricity, heat, light, and chemical affinities arc to be ascribed to vibra tory, circulating, and other internal motions or not. That these effects do not pass without the most remarkable internal motions, appears from the experiments upon light and upon electro-mag netism. The electrical current is a system of ro tative motions, upon whose directions, perhaps, all the disparity of positive and negative electricity depends. It is not improbable that even magnetism involves some rotations, and thus the opinion of Mr. Ampere comes to agree with ours, at least in this point. When the transmission of the electri cal current through liquid bodies is accompanied with a chemical decomposition, it seems necessary to admit that the substances styled clectro-positives and electro-negatives, must rotate in opposite di rections, and we may suppose that their neutral izing powers are connected with the propensities to those opposite rotations. The new discoveries, in short, reveal to us the world of secret motions, whose laws are probably analogous to those of the universe, and which deserve to be the subject of our most earnest meditations.