CHAPTER XIV. Michael Faraday

MICHAEL FARADAY

IT is strange that the man who did most for the progress of the science of electricity in the nineteenth century was the son of a London blacksmith. That man was Michael Faraday. He did not get much schooling, and what he did get was not more than reading, writing, and arithmetic.

His spare time was passed at home or in the streets. At the age of thirteen he was engaged as an errand boy to a bookbinder. After a year of running errands he was apprenticed to the trade of bookbinder, but the trade did not suit him at all, and all the time he could spare from it he spent in making chemical and electrical experiments. When he could get somebody to pay his admission fee, he attended lectures on these subjects.

When Faraday came of age he heard four lectures delivered at the Royal Institution in London by Sir Humphry Davy, the great Cornishman, who invented the safety lamp for miners. He was fired with the ambition to become a man of science. He had a great dislike for trade, and thought that all men of science were good and kind, and that it was the science which made them so. He took careful notes of the lectures, and when they were finished, he had the happy thought of sending his notes to Sir Humphry Davy, and explaining to him that his dearest wish was to follow in his footsteps. Davy was the best man he could possibly have written to on such a subject. He received Faraday’s letter very kindly, and promised to find some scientific work for him as soon as he could. He kept his word, and engaged Faraday the very next year as his assistant at the Royal Institution. At the age of thirty Faraday married, and brought his wife to the Royal Institution, where they lived together for six years. In that institution Faraday, in the year 1825, succeeded Davy as director.

Faraday’s first great achievement in electricity was to prove that an electric current could be produced by means of a magnet, without any electric battery. He made this discovery in the year 1831. Eleven years previously, the first connection between magnetism and electricity was discovered in Denmark. It was found that when a wire is stretched under a magnetic needle in the direction in which the needle points, and a current is sent through the wire, the needle turns round and tries to set itself in a direction across the wire. In this way an electric current produced some effect upon a magnet. Shortly after that fact was discovered, a great Frenchman of the name of Ampère found that one electric current attracts another that flows in the same direction, while it repels a current which flows in the opposite direction.

It struck Faraday that it might be possible to produce an electric current in a wire by simply starting a current in a neighbouring battery. He tried the experiment by stretching two wires side by side, and attaching the ends of one of the wires to an electric battery. In order to discover whether a current was travelling through the second wire, he brought a little magnetic compass up to it to see if the compass would set itself at right angles to the wire and so indicate a current. The needle indicated no current. Faraday then attached the ends of the second wire to an instrument called a galvanometer. That instrument consisted of a coil of wire in the centre of which the magnetic needle was placed. The current would pass through the coil of wire over the needle in one direction and under the needle in the opposite direction, and in each case it would tend to set the needle at right angles to the coil. The more turns the coil of wire had, the more powerful would be the effect. In this way, therefore, Faraday hoped to observe even a very small current.

But however long the current was kept passing through the first wire, the galvanometer showed not the slightest current in the second wire. This appeared very strange, because it was known that bodies may be made electric, or magnetic, by bringing them into the neighbourhood of electrified or magnetised bodies. It was natural, therefore, to suppose that a coil of wire could be made to carry an electric current by bringing it into the neighbourhood of another coil of wire which was already carrying an electric current. But in such things it is useless to endeavour to answer questions offhand. The only proper way is to try an experiment. Faraday did try the experiment as already described, and the result showed him that he was mistaken.

But Faraday was not discouraged easily. Thinking that perhaps the effect could be strengthened by winding the wires round a piece of soft iron, he took a ring of iron and wound two coils of wire round it, taking care that no part of the wire was touching any other part, or touching the iron. He then observed a curious effect, which was quite different from what he had expected. He found that the galvanometer gave a little start as soon as he turned on the current in the first coil. Then it came to rest again, although the current was still flowing. On turning off the current, the galvanometer gave a little start in the opposite direction, and soon returned to rest again. Faraday was in doubt whether this was really such an effect as he had been looking for. He wrote to a friend, “I think I have got hold of a good thing, but cannot say. It may be a weed instead of a fish that after all my labour I have at last pulled up.”

Faraday was a first-class experimenter, and his method is a good example of truly scientific work. When he found an effect which he could not quite account for, he changed the experiment in a great many different ways, in order to disentangle the causes and effects. The next time he tried to obtain a current by means of a magnet instead of another current. He took a natural magnet and wound a long coil of wire round and round it. The natural magnet had a cap of iron, and on pulling the cap off, a short momentary current appeared in the coil of wire. This momentary current could be shown either by attaching the ends of the coil of wire to a galvanometer or by bringing them close together. When that was done a small spark passed between the two ends of the wire.

This was another remarkable discovery, and Faraday proceeded to put it into another different shape. He wound a coil of wire round a bar of soft iron, and connected the ends with a galvanometer. Nothing happened so long as the bar of iron was not magnetised. But on suddenly placing the bar of soft iron between the two poles of a magnet, the bar became magnetised, and the galvanometer gave a momentary start. He removed the magnet, and the galvanometer gave a start in the opposite direction. Faraday expressed this by saying that a momentary current is induced in a coil of wire by starting or stopping a current in a neighbouring coil, or by creating or destroying a magnet near the coil.

Such induced currents are also called “induction currents.” They are familiar to many through the “induction coils” which are used to give electric shocks. In these induction coils there is a cylinder of iron surrounded by a coil of copper wire, and another coil of very fine wire round that again. A current is started and stopped in rapid succession in the first coil, and each starting and stopping induces a momentary current in the outer coil. These momentary currents are made to travel through the person who holds the handles. It is they that produce the curious pricking sensation.

Instead of sending a current through one coil inside another, we may take a coil through which a current is already passing, and put it inside another coil connected with a galvanometer. Each time the current-bearing coil is put in or taken out, the needle of the galvanometer moves, showing that a momentary current is passing through it.

When we consider that great cities are now lighted by means of these induced electric currents, it will be understood what a vast importance Faraday’s discovery bore within itself. When we pass the electric light works, a “central station” as it is called, we hear the throbbing of the engines which turn the machines designed to produce the electric current. These machines are called “dynamos.” A dynamo consists of two things. One of them is a great magnet which produces a powerful magnetic field. The other is a set of coils of wire which, driven by a steam engine or gas-engine, move through the magnetic field.

Each coil, as it moves in and out of the magnetic field, becomes the bearer of a momentary induction current, for to move a coil through a magnetic field produces the same effect as to make or unmake an electromagnet near the coil, or to start or stop a current in a neighbouring coil.

Great inventors have been working ever since Faraday’s time to improve and perfect the dynamo; some worked at collecting all the momentary induced currents into one smooth current always flowing in the same direction; others at providing ways and means for increasing the strength of the magnetic field or the speed of the engines. And thus to-day we have a vast industry occupying millions of men the world over, all due to a man who worked quietly and steadily in his laboratory, observing everything, neglecting nothing, and extracting the nuggets of golden truth from the mean-looking dust and dross of commonplace facts.

Faraday made a great number of other discoveries. He investigated the connection between chemistry and electricity, and founded a new science called “electrochemistry.” He also studied the action of a magnet on light, and found that a strong magnet is able to give a certain twist to a beam of light while it passes through certain substances (such as sulphide of carbon). Whenever he made such a discovery he was transported with delight. He was always of a vivacious and merry disposition. He said of himself: “I was a very lively, imaginative person, and could believe in the Arabian Nights as easily as in the Encyclopædia; but facts were important to me, and saved me. I could trust a fact, and always cross-examined an assertion.”

Towards the end of his life he suffered greatly from loss of memory. He helped himself by carrying about in his waistcoat pocket packets of cards, on which he wrote everything he wanted to remember. One of these has been preserved, and on it are found the following excellent maxims:--

“Remember to do one thing at once. Also to finish a thing. Also to do a little if I could not do much.”