Part 5

The assertion of Bernoulli and others, that the absolute force of the artificial magnet increases in the ratio of its superficies, stands corrected in the far more accurate experiments of Coulomb (published in his Treatise on Magnetism), which proves that the increase takes place (in a far greater degree) in the ratio of its length. The same naturalist even found means to determine that the directing powers of the needle, which he had measured by help of his balance de tortion, stand to the length of the needle in such a ratio as that, provided only the length of the needle is from forty to fifty times its diameter, the momenta of these directing powers will increase in the very same direct proportion as the length is increased. Nor is this all that may be deduced from the experiment last mentioned. If only the magnet be strong enough, it will show likewise that magnetism seeks the length. The proof is contained in the remarkable fact, that the iron interposed between the magnet and the magnetic needle breadthways constantly acquires its two opposite poles at both ends lengthways. Though the preceding experiments are abundantly sufficient to prove the position, yet the following deserves mention for the beautiful clearness of its evidence. If the magnetic power is determined exclusively by length, it is to be expected that it will manifest no force, where the piece of iron is of such a shape that no one dimension predominates. Bring a cube of iron near the magnetic needle and it will not exert the slightest degree of power beyond what belongs to it as mere iron. By the perfect equality of the dimensions, the magnetism of the earth appears, as it were, perplexed and doubtful. Now, then attach a second cube of iron to the first, and the instantaneous act of the iron on the magnetic needle will make it manifest that with the length thus given, the magnetic influence is given at the same moment.

That electricity, on the other hand, does not act in length merely, is clear, from the fact that every electric body is electric over its whole surface. But that electricity acts both in length and breadth, and only in length and breadth, and not in depth; in short, that the (so-called) electrical fluid in an electrified body spreads over the whole surface of that body without penetrating it, or tending ad intra, may be proved by direct experiment. Take a cylinder of wood, and bore an indefinite number of holes in it, each of them four lines in depth and four in diameter. Electrify this cylinder, and present to its superficies a small square of gold-leaf, held to it by an insulating needle of gum lac, and bring this square to an electrometer of great sensibility. The electrometer will instantly show an electricity in the gold-leaf, similar to that of the cylinder which had been brought into contact with it. The square of gold-leaf having thus been discharged of its electricity, put it carefully into one of the holes of the cylinder, so, namely, that it shall touch only the bottom of the hole, and present it again to the electrometer. It will be then found that the electrometer will exhibit no signs of electricity whatsoever. From this it follows, that the electricity which had been communicated to the cylinder had confined itself to the surface.

If the time and the limit prescribed would admit, we could multiply experiments, all tending to prove the same law; but we must be content with the barely sufficient. But that the chemical process acts in depth, and first, therefore, realizes and integrates the fluxional power of magnetism and electricity, is involved in the term composition; and this will become still more convincing when we have learnt to regard decomposition as a mere co-relative, i.e. as decomposition relatively to the body decomposed, but composition actually and in respect of the substances, into which it was decomposed. The alteration in the specific gravity of metals in their chemical amalgams, interesting as the fact is in all points, is decisive in the present; for gravity is the sole inward of inorganic bodies—it constitutes their depth.

I can now, for the first time, give to my opinions that degree of intelligibility, which is requisite for their introduction as hypotheses; the experiments above related, understood as in the common mode of thinking, prove that the magnetic influence flows in length, the electric fluid by suffusion, and that chemical agency (whatever the main agent may be) is qualitative and in intimis. Now my hypothesis demands the converse of all this. I affirm that a power, acting exclusively in length, is (wherever it be found) magnetism; that a power which acts both in length and in breadth, and only in length and breadth, is (wherever it be found) electricity; and finally, that a power which, together with length and breadth, includes depth likewise, is (wherever it be found) constructive agency. That is but one phenomenon of magnetism, to which we have appropriated and confined the term magnetism; because of all the natural bodies at present known, iron, and one or two of its nearest relatives in the family of hard yet coherent metals, are the only ones, in which all the conditions are collected, under which alone the magnetic agency can appear in and during the act itself. When, therefore, I affirm the power of reproduction in organized bodies to be magnetism, I must be understood to mean that this power, as it exists in the magnet, and which we there (to use a strong phrase) catch in the very act, is to the same kind of power, working as reproductive, what the root is to the cube of that root. We no more confound the force in the compass needle with that of reproduction, than a man can be said to confound his liver with a lichen, because he affirms that both of them grow.

The same precautions are to be repeated in the identification of electricity with irritability; and the power of depth, for which we have yet no appropriated term, with sensibility. How great the distance is in all, and that the lowest degrees are adopted as the exponent terms, not for their own sakes, but merely because they may be used with less hazard of diverting the attention from the kind by peculiar properties arising out of the degree, is evident from the third instance, unless the theorist can be supposed insane enough to apply sensation in good earnest to the effervescence of an acid or an alkali, or to sympathise with the distresses of a vat of new beer when it is working. In whatever way the subject could be treated, it must have remained unintelligible to men who, if they think of space at all, abstract their notion of it from the contents of an exhausted receiver. With this, and with an ether, such men may work wonders; as what, indeed, cannot be done with a plenum and a vacuum, when a theorist has privileged himself to assume the one, or the other, ad libitum?—in all innocence of heart, and undisturbed by the reflection that the two things cannot both be true. That both time and space are mere abstractions I am well aware; but I know with equal certainty that what is expressed by them as the identity of both is the highest reality, and the root of all power, the power to suffer, as well as the power to act. However mere an ens logicum space may be, the dimensions of space are real, and the works of Galileo, in more than one elegant passage, prove with what awe and amazement they fill the mind that worthily contemplates them. Dismissing, therefore, all facts of degrees, as introduced merely for the purposes of illustration, I would make as little reference as possible to the magnet, the charged phial, or the processes of the laboratory, and designate the three powers in the process of our animal life, each by two co-relative terms, the one expressing the form, and the other the object and product of the power. My hypothesis will, therefore, be thus expressed, that the constituent forces of life in the human living body are—first, the power of length, or REPRODUCTION; second, the power of surface (that is, length and breadth), or IRRITABILITY; third, the power of depth, or SENSIBILITY. With this observation I may conclude these remarks, only reminding the reader that Life itself is neither of these separately, but the copula of all three—that Life, as Life, supposes a positive or universal principle in Nature, with a negative principle in every particular animal, the latter, or limitative power, constantly acting to individualize, and, as it were, figure the former. Thus, then, Life itself is not a thing—a self-subsistent hypostasis—but an act and process; which, pitiable as the prejudice will appear to the forts esprits, is a great deal more than either my reason would authorise or my conscience allow me to assert—concerning the Soul, as the principle both of Reason and Conscience.

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FOOTNOTES