Chapter VIII: A Useful Dance

I may tell you quite frankly that I have never taken part in the perpetual dance of which I am about to tell you. I am of a free and roaming disposition, but I have often watched some of my fellow-electrons at this work. Of course, it is pleasant work, as all our duties are, now that man acknowledges our services.

We are responsible for the behaviour of the mariner's compass needle. It is we who cause it to point continually in one definite direction. If we ceased to dance around the iron atoms in the compass needle aboard a ship, the man at the helm could not tell in what direction he was going, and sooner or later he would be almost certain to wreck his vessel. For this service alone man ought to be grateful to us, but before I have finished my story, you will find that even this important duty is but a small affair when compared with many of our other tasks.

There is one matter I should like to make quite clear to you. Although we electrons are all identical, we have different stations to fill. You have doubtless become familiar with my roving disposition, and you probably think of me as a detachable electron. Then there are our friends who are locked up within the atoms of matter--part and parcel of the atom. And now I am introducing you to those electrons who act as satellites to the atoms, revolving around them at a comparatively great distance, just as the moon revolves around the earth. These are the electrons which give rise to the magnetism in a piece of iron. There are other electrons which perform very rapid revolutions around all classes of atoms, but I shall introduce these friends later on.

That phenomenon known as "magnetism" is due to the steady locomotion of electrons, as explained in the text. Here we see a large magnet attracting a tinned iron box which is tethered to the table by two cords. The result is that the box is supported in the air. The spiral wires are connected to the electro-magnet, an explanation of which is given in Chapter VIII.]

I need hardly remark that a piece of ordinary iron does not behave like a magnet. Indeed, it is fortunate that it does not. If it did, man could not get along with his work very well. The hammer would stick to the head of the nail it had struck, the fire-irons would stick to the fender, while the cook's pots and pans would hold on to the kitchen range. That would be a very stupid arrangement, but we electrons have really no say in the matter of arrangement. We are always on the move, performing a perpetual dance around the iron atoms, but the atoms arrange themselves in a higgledy-piggledy fashion, so that the electrons on one atom pull the aether in one direction while others pull the aether in an opposite direction. In this way the outward effect is not perceptible. When, however, man places a coil of wire around the iron, and makes a crowd of electrons march along the wire, these marching electrons affect the aether, which in turn influences the satellite electrons which are revolving around the atoms of iron. You may be somewhat surprised when I tell you that, owing to this aether disturbance, these satellite electrons are able to produce a rearrangement among the atoms. If you doubt my word, you may easily prove the truth of the statement. If you magnetise a long bar of iron you will find that its length is actually altered. This is due to our having disturbed the arrangement of the atoms.

Perhaps I should explain that when we force the atoms into their new condition, we can do so only under the aether stress set up by our fellow-electrons who are marching in the neighbouring wire. Whenever their march ceases the aether stress is withdrawn, and the atoms are able to fall back into their old higgledy-piggledy condition. In this way man is able to make a piece of iron a magnet and to unmake it as often as he cares by simply switching on and off the electric current from the wire surrounding the iron.

If a piece of hard steel is used in place of soft iron, then we find that the atoms are not so easily disturbed, but when they are once brought into line with one another, they will remain in their new condition after the aether disturbance has been withdrawn. It may seem strange to you that quite a small percentage of carbon atoms added to the pure soft iron should cause such a marked difference, but the matter seems plain enough to us. Man was so impressed with the manner in which the atoms were evidently fixed in their new condition that he spoke of _permanent magnets_. It is especially fortunate for man that these pieces of steel do retain their magnetism, and give us a reliable mariner's compass. But I shall tell you how you may disturb even these sedate atoms. If you hammer the metal very vigorously, or if you heat it to redness, you will find that the atoms have been freed from what appeared to be their permanent position, and they are back to their old higgledy-piggledy condition, so that we electrons are all opposing one another. Remember we are hard at work all the time although we may be giving no outward sign of our activity.

While we render an important aid to man by providing this permanent magnet for his compass, you will find that a very great deal of our assistance to man in his everyday life depends upon our behaviour in soft iron electro-magnets. It is in these that man can control our behaviour at will. It is through this simple piece of apparatus--the electro-magnet--that man has been able to accomplish so much in signalling to his friends at a distance. It is also by means of these electro-magnets that man can get us to turn an electric motor, and so on. But I must tell you, first of all, how we enable man to signal to a distance, or, in other words, how we carry man's news.

CHAPTER IX

HOW WE CARRY MAN'S NEWS

_THE SCRIBE'S NOTE ON CHAPTER NINE_

The electron explains wherein its method differs from all other
methods.

It is well known that within recent years the old iron telegraph
wires have been replaced by much lighter copper wires; the
electron explains the reason for this change.

It describes how the electrons manage to work the most widely
used form of telegraph instrument, which is called the "Morse,"
after its inventor.

Here we find one of the practical applications of the
electro-magnet described in the preceding chapter.