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

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.

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.

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.'

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.

Let us now see what happens in a galvanic cell when the two different metals are simultaneously exposed to the chemical action of the connecting fluid. Each metal by itself would undergo oxidation with greater or less intensity, and the calorific energy hidden in it would become free in the form of heat. This process suffers a certain alteration through the presence of the second metal, which sets up an alchemic tension between the two. Instead of a proper segregation of the primary polarity, heat-dust (in this case, heat-oxide), the heat remains matter-bound and appears on the surface of the two metals in a secondarily split form as positive and negative electricity.

Unlike electricity, magnetism was first known in the form of its natural occurrence, namely as a property of certain minerals. If we follow the same course which led us to start our study of electricity with the primitive process of generating it, we shall turn now to the basic phenomenon produced by a magnetic field already in existence. (Only when we have learnt all we can from this, shall we proceed to ask how magnetism comes into being.) Obviously, we shall find this basic phenomenon in the effect of a magnet on a heap of iron filings.

In the electric fishes, accordingly, sensation and will are brought into a peculiar interrelation. For the will-pole is related to its bodily foundation in a manner which otherwise obtains only between the nervous system and the psychological processes co-ordinated with it. These fishes then have the capacity to send out force-currents which produce in other animals and in man 'concussion of the limbs', or in extreme cases paralysis and even death. Through describing the process in this way we realize that electricity appears here as metamorphosed animal will, which takes this peculiar form because part of the animal's volitional system is assimilated to its sensory system in an exceptional manner.

Besides yielding a definite answer to the question of how far the seemingly discovered facts of science are manufactured facts, our newly won insight into the nature of the electric and magnetic polarties throws light also on the possibility of so handling both that their application will lead no longer to a cancellation, but to a true continuation, of nature's own creative deeds.