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Here, also, pure observation of the effect of a conductor in an electric field tells us that its action consists in the annihilation of the field. There is no phenomenon which allows us to state that this process takes place along the axis of the conductor. If we wish to obtain a picture of the true direction, we must consider the condition of space which arises in place of the electric condition that has disappeared.

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We remember that Galvani was led to his observations by the results of Walsh’s study of the electric fishes. While Galvani clung to the view that in his own experiments the source of the electrical force lay within the animal bodies, Volta saw the fallacy of that. He then conceived the idea of imitating with purely inorganic substances the set-up which Galvani had come upon by accident. The paradoxical result – as he himself noticed with surprise – was that his apparatus turned out to be a close replica of the peculiar organ with which the electric fishes are endowed by nature. We must now take a closer view of this organ.

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c13p76

‘Was it in this way’, Eddington asks, ‘that Rutherford rendered concrete the nucleus which his scientific imagination had created?’ One thing is certain: ‘In every physical laboratory we see ingeniously devised tools for executing the work of sculpture, according to the designs of the theoretical physicist. Sometimes the tool slips and carves off an odd-shaped form which he had not expected. Then we have a new experimental discovery,’

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Our functional conception of matter, developed earlier (Chapter XI), allows us to recognize in these two substances representatives of the Salt-Sulphur polarity. Indeed, glass as a mineral substance, which actually owes its specific character to the presence of silicon in it, clearly stands on the phosphoric-crystalline side, while resin, being itself a sort of ‘gum’, on the sulphurous-volcanic side. In fact, sulphur itself was soon found to be a particularly suitable substance for producing ‘resin’-electricity.

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Any two of these metals constitute a voltaic cell. Its electromotive force is determined by the distance in the series between the metals used. Just as in the case of frictional electricity, the kind of electricity which is supplied by a certain metal depends on whether the other metal with which it is coupled stands to the right or to the left of it in the series.1

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With the possibility of turning the cancellation of the electrical condition of space into a continuous process, it became possible to observe that the neutralization of electric charges entails the appearance of heat and magnetism. We must now ask which are the qualities of electricity on the one hand, and of heat and magnetism on the other, which account for the fact that where electricity disappears, the two latter forces are bound to appear. Since magnetism is the still unknown entity among the three, we must now deal with it.

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The electric organ of such a fish consists of many thousands of little piles, each made up of a very great number of plates of two different kinds, arranged in alternating layers. The two kinds differ in substance: in one case the plate is made from a material similar to that present in the nervous system of animals; in the other the resemblance is to a substance present in the muscular system, though only when the muscles are in a state of decay. In this way the two opposing systems of the animal body’ seem to be brought here into direct contact, repeated many thousands of times.

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To this analogy Eddington adds the following even more drastic one: ‘Procrustes, you will remember,’ he says, ‘stretched or chopped down his guests to fit the bed he constructed. But perhaps you have not heard the rest of the story. He measured them up before they left the next morning, and wrote a learned paper On the Uniformity of Stature of Travellers for the Anthropological Society of Attica.’

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Now the usual way of producing one kind of electricity is by rubbing resin (or sulphur, or ebonite) with wool or fur, and the other by rubbing glass with leather. At first sight, it does not seem as if the two counter-substances represent the required alchemic counter-poles to resin and glass. For both hair and leather are animal products and therefore seem to be of like nature. Closer inspection, however, shows that they do obey the rule. For hair, like all horny substances, is a dead product of external secretion by the animal organism. An ur-phenomenal example of it, showing its kinship to glass-like substances, is the transparent cornea of the eye, close to the crystal-lens. Leather, on the other hand, is a product of the hypodermic part of the body and, as such, belongs to those parts of the organism which are filled with blood, and, therefore, permeated with life. (Note as a characteristic of leather that it requires a special treatment, tanning, to make it as immune from decay as hair is by nature.) Hair and leather, therefore, represent in themselves a salt-sulphur polarity, and thus fulfil the corresponding function when brought together with resin or glass respectively.