Here the electron explains its behaviour in a dynamo at work.The principle of the dynamo was discovered by Faraday in the thirties of last century.He found that when a coil of wire was moved through a magnetic field, there was a current of electricity induced in the moving coil.Experimental machines were constructed, and after a while a practical dynamo was evolved.Wires are attached to a dynamo and the electric current is led out.This current may be conducted to a distant tramway car, and, by sending the current through an electric motor, mechanical motion is produced and the car propelled along.An electric motor is practically the same as a dynamo, but instead of turning its coil round in order to produce an electric current, we pass a current into the coil and it moves round. It will be sufficient to leave the electron to tell its own story.
Here the electron explains its behaviour in a dynamo at work.
The principle of the dynamo was discovered by Faraday in the thirties of last century.
He found that when a coil of wire was moved through a magnetic field, there was a current of electricity induced in the moving coil.
Experimental machines were constructed, and after a while a practical dynamo was evolved.
Wires are attached to a dynamo and the electric current is led out.
This current may be conducted to a distant tramway car, and, by sending the current through an electric motor, mechanical motion is produced and the car propelled along.
An electric motor is practically the same as a dynamo, but instead of turning its coil round in order to produce an electric current, we pass a current into the coil and it moves round. It will be sufficient to leave the electron to tell its own story.
This is another of those roving commissions in which I have been privileged to take part on more than one occasion.
If you think of the giant size of an electric tramway car or a railway train, and try to compare one of these with an electron, such as your humble servant, it will seem quite ridiculous that I should suggest that it is we electrons who move those huge vehicles. Yet such is the actual case.
Of course we require the application of very considerable power to urge us to so heavy a task. All the energy which we can get from a few electric batteries might enable us to drive a toy car, but when it comes to turning the wheels of a real car or train, we require a correspondingly greater amount of energy.
I may as well tell you quite frankly thatwe electrons are only the intermediaries or go-betweens. Indeed, you must have noticed that in every case we act merely as a connecting link between matter and the æther, and between the æther and matter.
But what I want to tell you of, is the part we play in moving an electric car or railway train. It is really all very simple if you could only see it from our standpoint. Picture a host of us attached to copper atoms in a coil of wire which is being moved through that disturbed æther called amagnetic field. We are set in motion immediately. It is true that when we are moved forward into the field we march off in one direction, only to be arrested and made to move off in the opposite direction as we leave the field, but it really makes no difference in our working capabilities as long as we are kept on the move. This is what is actually taking place in the armature of a dynamo as it revolves between the poles of the electro-magnet. There is no peace for us so long as the coil is kept revolving; we are kept in a constant state of rapid to-and-fro motion.
By permission of Siemens Schuckert WerkeBerlinA Train Impelled by Moving ElectronsIt is remarkable that the motion of electrons in an electric conductor can result in the movement of heavy vehicles. How this comes about is explained inChapter XII.
By permission of Siemens Schuckert WerkeBerlin
A Train Impelled by Moving Electrons
It is remarkable that the motion of electrons in an electric conductor can result in the movement of heavy vehicles. How this comes about is explained inChapter XII.
This is all we electrons do in a dynamo, but when the ends of the outer circuit ormains are brought into contact with the ends of our revolving coil, we set the electrons in the mains surging to and fro in step with ourselves. Man describes this motion of the electrons in the mains as analternating electric current, but by a simple commutator on the dynamo he may arrange that we set the electrons marching in one direction in the mains. This he describes as adirect electric current.
It is a matter of indifference to us whether man drives our coil round by means of a steam-engine, a water-wheel, or a wind-mill; all that we electrons want is to be kept surging or vibrating to and fro. Now you will be able to appreciate how we electrons get up sufficient motion to enable us to perform what I have described asour heaviest duties.
Perhaps you will find it difficult to believe me when I tell you that as we march along the connecting wire to a distant tramway car we transmit the energy through the surrounding æther, and not through the wire. This is our mode of working in every case, whether it be an electric bell, a telegraph, or telephone. That is to say, whilewe electrons move from atom to atom in the connecting wire, it is the disturbed æther surrounding us which transmits the energy. You must have realised by this time how very intimate is the relationship between ourselves and the æther.
To return to the tale of our tramway work, you will picture my fellow-electrons aboard the car being energised by the incoming current. Those electrons present in the armature coil of the motor are set into motion, as also are those in the wire of the neighbouring electro-magnet. The result is that these two sets of electrons so disturb the æther and affect one another that the coil is moved round into a different position. You will remember the experiment of which I told you, in which a magnetic needle would insist always in taking up a position at right angles to a wire in which an electric current is passing. Well, when the motor coil has turned into its new position, we electrons receive an impulse from our friends in the line-wire which causes us to retrace our steps in the coil. This action of ours causes the coil to make a further movement in the same direction as at first. Again we changeour direction of march, and again the coil changes its position towards the electro-magnet. The sole duty of these electrons in the armature coil is to keep surging to and fro, while those electrons in the electro-magnet keep up a steady march in one direction. This arrangement necessitates the armature coil to keep changing its position continually, and when we have the armature coil spinning round at a steady pace, it is easy for man to connect the armature to the axles of the tramway car and cause us to drive the wheels round.
I need hardly say that it makes no difference to us whether we are asked to drive a tramway car, a railway train, or a host of machines in a factory or workshop. All that we electrons in the motor require is to have sufficient energy passed along to us from our fellows in the distant dynamo. Again I admit frankly that the atoms of matter play a very important part in these our heaviest duties, but you will see that without our active assistance they could not transmit the necessary energy to a distant car or train.
While it has been known for a long time thatlightandradiant heatare merely waves in the æther, it was not known until recently how these waves were produced.The discovery of electrons has given us a reasonable solution of our difficulty.The electron explains the actions of its fellows in this great work of producing light and heat.Incidentally the electron explains how they produce an aurora in the heavens, and how it is that the earth has become a negatively electrified body.
While it has been known for a long time thatlightandradiant heatare merely waves in the æther, it was not known until recently how these waves were produced.
The discovery of electrons has given us a reasonable solution of our difficulty.
The electron explains the actions of its fellows in this great work of producing light and heat.
Incidentally the electron explains how they produce an aurora in the heavens, and how it is that the earth has become a negatively electrified body.
Every living thing is dependent upon our activities. It is we electrons who send out heat and light from the sun, and it is we who receive these on their arrival upon this planet. Our action in the matter is really very simple, but until man discovered our existence, he was mystified considerably.
We were amused to hear man say that the atoms of incandescent matter in the sun produced waves in the æther, and that when these æther waves fell upon other atoms on this planet, these were set into a state of vibration, thus producing heat and light. Now if man had only stopped to think, he would have seen how ridiculous it was to speak of atoms of matter producing waves in the æther. He ought to have known that atoms of matter cannot affect the æther,for it offers no resistance to matter moving through it.
Man might have pictured himself riding on the back of this great planet, flying through space at a speed very similar to that of a rifle bullet, and yet even the flimsy blanket of air surrounding the planet is not disturbed by the æther through which it is rushing.
It is true that the atoms of matter play an important part in the origin of heat, but the atoms in the sun could no more affect the atoms on the earth than could a man on the earth push the moon about. It is the very intimate connection between us electrons and the all-pervading æther which enables our fellows in the sun to communicate with those of us upon this planet. Where would man be without us?
By permission of Siemens Schuckert WerkeBerlinProtection Against a Discharge of ElectronsWhen a man is encased completely in an over-all made of flexible metallic gauze he is proof against shock due to a discharge of high-tension electricity. The part played by electrons in the case of electric shock is explained inChapter IV.
By permission of Siemens Schuckert WerkeBerlin
Protection Against a Discharge of Electrons
When a man is encased completely in an over-all made of flexible metallic gauze he is proof against shock due to a discharge of high-tension electricity. The part played by electrons in the case of electric shock is explained inChapter IV.
I cannot understand wherein man should find any mystery in connection with this very simple action of ours. You will picture our distant fellow-electrons making very rapid revolutions around the atoms of matter to which they are attached as satellites. Just as the moon circles around the earth, so do we circle around our atoms, but at an enormously greater speed. Of course the whole length of our orbit is inconceivably small, and the speed of our revolutions is inconceivably great. It is our rapid motion through the æther which produces those waves known to man as radiant heat and light. Some one may ask how it is that we electrons can disturb the æther while the giant atoms cannot. The obvious answer is that we are not matter, but electricity; we are not in the same category as atoms of matter.
To complete the picture which I was drawing, you have only to think of the æther waves arriving upon this planet and disturbing sympathetic electrons, causing them to revolve around their atoms in similar fashion to our distant fellows who are producing the æther waves.
It may be that some people get confused between this action and that of those electrons who are shot off bodily from the sun towards the earth. Believe me, there is no connection between the two things. The stream of electrons shot off from the sun is deflected towards the magnetic poles of the earth, and as the electrons enter the upper layers of the atmosphere they produce that beautifulluminous effect which man describes as anAurora.
I have never taken part in one of these great displays, for, as far as my recollection goes, I have never been in the sun, although some fellow-electrons declare that at one time we were all in the same great glowing mass of which the sun, and every member of the solar system, formed a part. However that may be, I certainly have no experience of auroræ, but I have assisted in producing the very same effect upon a small scale within a vacuum tube. The air remaining in these so-called vacuum tubes is just as rarified as the air in the upper layers of the atmosphere, and when we are shot across the tube we act in the same way as those electrons arriving upon this planet from the sun.
You will observe that as a surplus of electrons arrives upon the earth from the sun, the earth is naturally a negatively electrified body, but I need hardly say that the earth does not keep all the electrons which arrive upon it.
My scribe points out that I am wandering from the story which I set out to tell in this chapter, so I shall try and please him.
The direct cause of light, whether it be natural or artificial, is the rapid motion of electrons around atoms of matter. If they revolve at a comparatively slow speed they produce those æther waves which man callsradiant heat. If these satellite electrons, however, desire to affect the eye of man, they have to move around at a very much greater speed. If we travel at too fast a speed, then we cease to cause the sensation of light. But, believe me, all the waves we make are of the same nature, no matter what names man has given them. The only difference we can make in the waves is the rate at which they follow one another. Of course we can also make them larger or smaller in height, or, in other words, of greater or less amplitude, but that does not affect their properties.
In the following chapter I shall tell you of some remarkable phenomena which our different æther waves produce in the brain of man.
Colour is merely a sensation in the brain.What the electrons really produce are æther waves, and these give rise to the sensations of colour.However, the electrons may claim to produce colour in the same sense as we savages produce pain in fellow-men by firing rifle-bullets at them.The electron explains how some objects appear white, while others are red, and so forth.It explains also how electrons produce artificial light.The electron twits man upon his ridiculously wasteful processes of obtaining artificial light.
Colour is merely a sensation in the brain.
What the electrons really produce are æther waves, and these give rise to the sensations of colour.
However, the electrons may claim to produce colour in the same sense as we savages produce pain in fellow-men by firing rifle-bullets at them.
The electron explains how some objects appear white, while others are red, and so forth.
It explains also how electrons produce artificial light.
The electron twits man upon his ridiculously wasteful processes of obtaining artificial light.
In the preceding chapter I have been telling you how we electrons produce waves in the æther ocean. I pointed out that if we make the waves follow each other at too slow or too fast a rate they fail to affect man's eyes.
It may seem strange to you that only a very small range of our æther waves should affect man's visionary apparatus. Of course this limitation lies beyond our province; we can produce endless variety of æther waves—it is man's organs which fail to appreciate the bulk of these. However, there is plenty of variety in the sensations which we can produce in man. If we make the waves follow each other at a certain speed, man says he has the sensation ofred. If we move faster, he speaks oforange-colour, and as we increase our speed he names his further sensations asyellow,green,blue, andviolet. Then if wecombine all these waves—that is, if we produce them all at one time—he says he has the sensation ofwhite. If we produce none of these waves, he calls the resultblack.
While we electrons are very versatile, our actions are dependent in a great measure upon circumstances. For instance, if an electron is acting as a satellite to one particular kind of atom, its rate of revolution around that atom may be very different from that of an electron similarly attached to another kind of atom. We electrons are all identical, but the speed of revolution is determined by the kind of atom. The reason is very simple; electrons revolve around some atoms at a much greater distance than they would around other atoms. Those making only the smaller orbits not only get around their atoms in less time, but they are also travelling at a greater pace. It is this fact which enables the electrons to produce the various wave-lengths which stimulate the different colour sensations in the brain of man.
I think you will have no difficulty in seeing how it is that we come to produce such a variety of wave-lengths—in other words, how we are able to make the waves followeach other more or less rapidly. You will understand that we do not produce colours; we merely make various waves in the æther, and these waves excite the colour sensations in man. I mention this simple fact, because I hear many people speaking of our æther waves as "coloured rays," which, of course, is quite a ridiculous description.
Suppose some of those waves which give rise to the red sensation happen to fall upon a lump of matter which contains only electrons capable of producing waves that affect the green sensation. What will happen? There will be no response, and the object, although viewed by "red light," will appear black.
If an object, such as the white paper upon which my scribe is recording my story, contains a variety of atoms with electrons capable of revolving at all the different rates which produce colour sensations, then when "white light" falls upon the object it appears white (all the colour sensations combined). If, on the other hand, a "red light" only falls upon it, then only the electrons capable of responding to that rate of wave will be set in motion, and the object will appear red, and so on with the other rates of æther waves.
So far I have been telling you what happens when different waves of light fall upon us. Now I shall endeavour to explain how man has caused us to produce artificial light. At present all man's methods in this direction are dependent upon making some substance so hot that it becomes incandescent. Even his most modern methods seem to us to be ridiculously wasteful and most roundabout. I shall speak only of the electric glow lamp, as I have had some experience in connection with this.
On one occasion I had been taking part in a regular forward march from copper atom to copper atom in a conducting wire. I had no idea of the purpose of our march till I suddenly found myself handed over to some carbon atoms, who were in a very lively state of vibration. We had much more difficulty in making our way through this substance, and it was the passive resistance offered to the advance of the electrons who had preceded me that had driven the carbon atoms into this state of great excitement. In our march through the copper conductor we had been offered very little resistance, so that we had left the copper atoms in peace—at least mancould not detect easily any excitement (heat). But so long as our forced march was maintained among the carbon atoms, so long did the high temperature exist.
You will understand I and the other marching electrons did not produce the waves of light sent out by the glow lamp. What we did was to set the atoms of carbon into a rapid vibratory state, and they in turn caused their satellite electrons to hasten their pace. Some electrons produced one rate of waves, and some another rate, but by the time the carbon was incandescent there were electrons sending out all the variety of wave-lengths, the combination of which produces the sensation of white.
I have accused man of adopting very wasteful processes, so I had better explain the matter. In the preceding description of what is occurring in an electric glow lamp, I have spoken only of those æther waves which constitute light. But there are myriads of electrons in the carbon of the glow lamp that never attain the requisite speed to produce those waves; they revolve around their atoms at too slow a rate. They certainly disturb the æther, but the crests of the wavesare so far apart that they do not affect the eyes of man. The business of these waves is to set up heat in the bodies upon which they fall. You may be surprised to know that in this contrivance of man, called an electric glow lamp, and, indeed, in all his other artificial light-producers, he causes far more electrons to produce radiant heat than the desired light waves. A most wasteful process!
Man has a long way to travel yet before he succeeds in producing artificial light by a reasonable process. Indeed I doubt if any of you can realise, as we do, how exceedingly stupid the existing methods are. Think for a moment of the glow-worm, in which we electrons produce light without setting up any wasteful heat waves. There is a strong contrast between this peaceful plan and that of the excited carbon atoms. When will man succeed in discovering this secret of ours?
It is remarkable that man has been able to discover what the distant stars are made of.Our knowledge concerning the chemistry of the stars has been obtained by means of the spectroscope, in which a beam of light from the star is passed through a glass prism.The result is the well-known image of the coloured spectrum, in which certain well-defined lines appear, according to the distant elements originating the æther waves.The electron explains the whole subject from its own point of view.
It is remarkable that man has been able to discover what the distant stars are made of.
Our knowledge concerning the chemistry of the stars has been obtained by means of the spectroscope, in which a beam of light from the star is passed through a glass prism.
The result is the well-known image of the coloured spectrum, in which certain well-defined lines appear, according to the distant elements originating the æther waves.
The electron explains the whole subject from its own point of view.
It is only within recent times that man has observed that we send messages from the distant stars to this planet. But there is nothing new to us in this proceeding; we have been busy sending these messages ever since the solar system was formed. Through all those ages we have kept on sending these messages, knowing that in time man must come to take notice of them.
If the subject should happen to be new to you, you will be anxious to know to what kind of messages I refer. Needless to say, they are wireless messages—waves in the great æther ocean. The waves, to which I refer specially, fall within that small range of which I told you something in the preceding chapter. In other words, they are those waves to which man has given thenamelight. But what special information do these waves, coming from the stars, convey to man? They tell him of what materials these distant stars are made. Needless to say, it is we electrons who produce those informative waves.
You are familiar with our method of producing waves. You know that we whirl around the atoms of matter at prodigious speeds, and that according to the number of revolutions we make per second, we produce waves of corresponding frequencies.
In an earlier chapter I have hinted that the speed of the revolving electron is determined by the kind of atom to which it acts as a satellite. For instance, when electrons revolve around iron atoms they produce certain wave-lengths, while those moving around hydrogen atoms produce an entirely different series of waves. But how is man to recognise these?
It is quite evident that man may gaze at a distant star and be little the wiser concerning the different lengths of the waves which impinge upon his eyes. He may observe that the sensation is inclined to red, from which he may infer that the waves are longones—that they are farther apart than some of the waves produced by a white-hot body. But had man been content to try and decipher our wireless messages in this rough-and-ready manner, he would never have gained the interesting information which we have now placed in his hands. How, then, did we enable man to read our messages?
Our plan may seem to be somewhat mysterious, but I assure you that it is really very simple. When these æther waves of light fall upon a triangular prism of glass, the waves are bent out of their normally straight path. But the point that may seem strange to you, is that those waves which produce the sensation of red are not bent so much as the others. The more rapidly the waves follow one another, the greater is the bending of such a ray from its original direction. In this way the various wave-lengths are all spread out, so that they form an image like a coloured ribbon, red at one end, being followed by orange, yellow, green, blue, and violet. Every man must be familiar with this coloured spectrum. When some of my fellows are enclosed in drops of water in the air they produce a great rainbow spectrumacross the heavens. But I must tell you how we electrons succeed in bending these rays of light.
I have told you already how we either absorb or reflect the æther waves which happen to fall upon us. In most substances it is only those electrons very near the surface that are disturbed. They succeed in stopping the waves. They may do this in either of two different ways. If the satellite electrons are attracted strongly by their atoms, the electrons will spin around the atoms keeping time to the movements of the incoming waves, and in this way the electrons take up the energy of the waves. In doing this, the electrons send out fresh waves in the æther. This is the real explanation of what man callsreflectionof light.
The Spectroscope and the Electrons' Wireless MessagesThe spectroscope is seen in the extreme left of No. 1 photograph. The instrument is explained atpage 207.The operator is passing an electric current through a glass tube containing a rarefied gas, causing the gas to become luminous. When he examines its light through the spectroscope he sees bright lines as shown in photograph No. 2, and from the position of these lines he can tell what substance is producing the light. No. 2 is the spectrum of mercury vapour. No. 3 is part of the spectrum of the sun. Note the dark lines, as explained in the text.
The Spectroscope and the Electrons' Wireless Messages
The spectroscope is seen in the extreme left of No. 1 photograph. The instrument is explained atpage 207.
The operator is passing an electric current through a glass tube containing a rarefied gas, causing the gas to become luminous. When he examines its light through the spectroscope he sees bright lines as shown in photograph No. 2, and from the position of these lines he can tell what substance is producing the light. No. 2 is the spectrum of mercury vapour. No. 3 is part of the spectrum of the sun. Note the dark lines, as explained in the text.
In the second case, the electrons are not so firmly attached to their atoms, so that the incoming waves dislodge them, and they are knocked about from atom to atom, and in this way the energy of the waves is frittered away. Man speaks of the light having beenabsorbedby the substance upon which it fell. In both cases the only electrons which take part in these actions are those electrons whocan move in sympathy with the incoming waves.
It will be clear to you that only those of us who are near the surface of a substance know anything about these incoming waves. The electrons attached to atoms in the interior of the substance are left in peace, owing to the defensive actions of our fellows on the outside. But this is not the case with all substances. There are some congregations of atoms through which the æther waves can make their way. Man calls such materialstransparent; for example, glass and water are transparent substances. The fact of the matter is that in such substances none of us are able to respond to the incoming waves, and so we cannot stop them. I should say almost none of us, for there are always a few electrons present who happen to be in sympathy with the incoming waves. That is why no substance is perfectly transparent.
The point concerning which I wish to speak in particular is this. Although we allow the æther waves to pass through such substances, we do offer some slight resistance to the passage of the waves; the faster the to-and-fro motion of the waves, the more resistance dowe offer. That is why the waves of highest frequency are bent farthest from the straight line when passed through a glass prism. We actually force the æther waves to travel slower through a piece of glass than through the air.
Now there should be no mystery concerning our action in a triangular piece of glass. Whatever combination of æther waves falls upon it, the different trains of waves are sorted out according to their frequencies. Suppose, for instance, that æther waves emitted from some incandescent sodium are passed through a glass prism. The bulk of the electrons attached to the sodium atoms are capable of revolving at speeds which produce waves causing the sensation of yellow. Hence there will appear a very distinct line of yellow light in the spectrum. But why should the light be in the form of a line? Simply because our æther waves are passed through a narrow slit in a shutter. But I need not trouble you with further details of our actions, which, although very simple to us, may seem somewhat strange to you.
You will understand, however, that we form bright lines in different parts of thespectrum, according to the kinds of atoms to which we are attached. It was this fact which attracted man's attention to our wireless messages. He soon discovered the meaning of these lines, for he commenced to take exact notes of the different positions in which we placed these lines. He saw that when we were attached to hydrogen atoms we always produced three prominent lines; a very distinct line in the red section, another in the blue part, and a third one somewhat fainter and farther along in the blue. On the other hand, when attached to sodium atoms, we produced two very distinct lines in the yellow. When attached to iron atoms we produced a great variety of lines in the spectrum. Of course these substances have to be incandescent to enable us to produce the æther waves.
Now it will be clear to you how we send wireless messages from the distant stars. These stars are great masses of flaming gases, so that the satellite electrons are kept busy dancing attendance to excited atoms. The electrons are constantly sending out æther waves, which reach this planet. We sort out these waves when man passes them through aglass prism, mounted in a telescope arrangement which he calls aspectroscope. He then examines the positions of the lines we produce in the resulting spectrum, and from these he knows what kinds of atoms are present in the distant star. It is we who have informed man that there are forty different materials in the sun, the most common of which are hydrogen, sodium, iron, copper, nickel, and zinc. Of course these all exist in a gaseous form.
There is one point about which I need hardly trouble you, although it is worth mentioning in passing. While we produce bright lines in the spectrum of any incandescent substance on this planet, our messages from the stars appear as dark lines. The reason for this is that there are cooler masses of the gases surrounding the incandescent masses forming the stars, and these cooler gases completely absorb the waves we produce. So completely are these waves absorbed that blank spaces are left in the spectrum, and these are the dark lines to which I refer. As they are in the same positions that the bright lines would have occupied had the waves reached the earth, itmakes no difference to the reading of our messages.
Curiously enough, some of our actions in forming lines in the spectrum led to our actual discovery by man; but I shall tell you of this in the following chapter.
Several men of note declared that "little particles" revolved around the atoms of matter, and that it was the motion of these particles which produced the well-known æther waves of light.This idea was suggested by the result of certain mathematical calculations.It was some time before real experimental proof was obtained.The electron tells its own tale of this great discovery.When the electron speaks of a spectrum line being shifted up or down the scale, it means towards the violet or the red end respectively.We may picture the spectrum as analogous to the keyboard of a piano.In the second part of this chapter, the electron explains how it has enabled man to discover that certain stars are approaching the earth, while others are receding from it.
Several men of note declared that "little particles" revolved around the atoms of matter, and that it was the motion of these particles which produced the well-known æther waves of light.
This idea was suggested by the result of certain mathematical calculations.
It was some time before real experimental proof was obtained.
The electron tells its own tale of this great discovery.
When the electron speaks of a spectrum line being shifted up or down the scale, it means towards the violet or the red end respectively.
We may picture the spectrum as analogous to the keyboard of a piano.
In the second part of this chapter, the electron explains how it has enabled man to discover that certain stars are approaching the earth, while others are receding from it.
We electrons had waited long ages for man to acknowledge our services, but we did not despise the acknowledgment which a few men accorded us upon the basis of their mathematical calculations. It was natural, however, that we should want something more definite than this.
You can imagine our joy when real experimental proof of our existence was established. Perhaps you think that we should have been satisfied with this. But even this did not bring acknowledgment from many outside scientific circles, and not even from all within those circles. As our services to man are universal, we feel that all men should become acquainted with our doings. Indeed that was the chief argument used by my fellow-electrons, who urged me to write thisautobiography. The story of our actual discovery by man is an interesting one.
It all came about in a very simple manner, but in quite a different way from what most electrons expected. Man reasoned within himself that if we electrons really did revolve around atoms and thus produce waves in the æther, as had been suggested, he ought to be able to affect our movements by disturbing the æther in which we were revolving. Of course man cannot disturb the æther directly; he must employ some of us to do this for him. He caused us to produce a very powerful magnetic field, which, as you know, is a disturbance of the æther. Man did not bother thinking aboutusin this connection; he simply sent an electric current around an electro-magnet, but I have explained to you the very active part we play in electric and magnetic actions.
From my story in the preceding chapter, you are aware that man had observed the meaning of the bright lines in the spectrum of any incandescent body. When he examined the æther waves we send out from sodium atoms, he found two very distinct lines in the yellow. Because of the brightness ofthese lines, man selected a sodium flame to experiment with in the present case.
You will picture a great host of my fellow-electrons revolving around the atoms in a sodium flame. The flame was placed between the poles of a very powerful electro-magnet, and a beam of æther waves (light) produced by us was directed into the spectroscope. The experimenter focussed all his attention upon one of the bright yellow lines. He noted very carefully the exact position in which we placed it. He then produced the magnetic field around the flame, in which my fellow-electrons were revolving at a steady pace, and, behold, the line which he was watching split up into two lines, one taking up a position a little higher up the spectrum scale, and the other going a little lower down towards the red end. What could this mean?
Man had no difficulty in knowing the cause of this alteration; indeed, it was exactly what he had hoped would take place. Of the two new lines, one represented waves a little shorter, while the other line indicated waves a little longer or farther apart, than the original waves forming the single line. Thiscould only come about by some of the electrons having had their rate of revolution increased, while that of others had been reduced. These alterations were due to the æther disturbance (the magnetic field). Those electrons whose orbits happened to lie in one position had their rate of revolution increased, while those whose orbits lay in another position had their speed reduced. Man was convinced at last that we "particles" were real existing things.
Whenever man withdrew the æther disturbance, the electrons fell back into their natural rate of revolution, and the original single line appeared in the spectrum.
I took no part in the original experiment which gave absolute proof of our existence, but since then I have been present in a laboratory when the same experiment has been repeated.
This is not the only case in which we alter the positions of definite lines in the spectrum. Indeed, we have given man some interesting information about the motions of distant stars—information which he could not have obtained in any other way. We have sent wireless messages from distantstars, indicating that they were approaching the earth, while electrons aboard other stars have signalled that they are receding from the earth. All this may seem mysterious to you, and yet our actions in the matter are very simple. Indeed, we do nothing but what I have told you of in the preceding chapters. We send out definite wave-lengths in the manner described already. But if we are on board a star which is travelling towards the earth, our waves will naturally follow a little closer at each other's heels. On the other hand, if the star is receding from the earth, the waves must be a little farther apart than they would be if the star were at rest.
You will understand that the electrons are revolving at the same speeds in both cases, but the forward movement of the star crowds the waves together, while a receding star stretches them out a little farther apart. The result at the receiving end is that the crowded waves are just as though they had come from electrons revolving at a greater speed than is actually the case. Hence the line appears farther along the spectrum, up the scale of frequencies, than would havebeen the case had the star not been moving forward in the line of sight. Thus if the hydrogen lines, of which I have spoken elsewhere, should appear higher up the spectrum than usual, then man knows that the star from which these waves are coming is approaching the earth.
It will be evident that when known lines in the spectrum are shifted down the scale (towards the red end of the spectrum), then the rate of the waves has been decreased, and man knows that the star carrying these stimulating electrons is receding from him.
You will observe that we electrons perform no new duty in connection with this matter; it is entirely the motion of the body carrying us that alters the positions of the lines. But I must hasten on to tell you of some personal experiences.
The present generation were all very much interested in the discovery of X-rays.With the aid of a battery and an induction coil, man causes an energetic electrical discharge to pass through a vacuum tube.When the flying electrons strike upon a little metal target placed in their path, they produce the well-known Roentgen rays.We have all become familiar with the great penetrating powers of these rays.The electron may be left to tell its own story.
The present generation were all very much interested in the discovery of X-rays.
With the aid of a battery and an induction coil, man causes an energetic electrical discharge to pass through a vacuum tube.
When the flying electrons strike upon a little metal target placed in their path, they produce the well-known Roentgen rays.
We have all become familiar with the great penetrating powers of these rays.
The electron may be left to tell its own story.
It was no surprise to us that we could produce what man calls X-rays, but we were very much surprised at the use to which man put these splashes which we made in the æther. A limited number of us had been producing X-rays on our own account for many ages, but I shall tell you of that in a later chapter, when you will hear how we made the world talk.
I must tell you of my own experiences in connection with these X-rays, which I hear some men describe also asRoentgen rays. I found myself once more within a large vacuum tube, and as soon as I felt a crowd of my fellows pushing me forward, I was quite prepared to be shot across the tube, as on previous occasions. Personally, I was not prepared for what was to come. Just as we reached the centre of the tube wecollided with a metal plate or target. It was no joke to be pulled up so suddenly when travelling at a terrific speed. I noticed at the time that our very sudden stoppage had a peculiar effect upon the æther. Of course we never bothered about a name for this disturbance; it is man who requires to have names for everything. He was quite right to call this æther disturbance "X-rays," for even now he does not know the real nature of these. I have heard him describe them as thin pulses in the æther, but there is something more.
I may as well confess that although we observed this æther disturbance arising from our sudden stoppage, we paid little attention to it, until it became apparent that man was continuing to produce these rays for some special purpose. He had discovered that we could shoot these rays right through many solid substances which were not transparent to light. But I have not told you how man came to know that we could produce these penetrating rays.
On one occasion we were sending out these rays, which, by the way, do not cause any sensation in man's visionary apparatus. Theroom was in darkness. Some of the invisible rays fell upon a collection of small chemical crystals which were fixed on the surface of a screen. Our fellow-electrons, who were attached to the atoms of the crystals, were bestirred into action. They could not reflect the X-rays, but they set up regular trains of waves in the æther, some of which came within the range that affects man's vision. Man knew that this chemical screen could not produce light on its own account, and it became apparent that the vacuum tube must be sending some æther waves towards the chemical screen.
As the electrons on the screen produced an æther disturbance different from that which fell upon it, man called this afluorescent screen.
At first we took merely a passing interest in the experiments which man made with these X-rays of ours, for it seemed to us as though man thought them only good enough for amusing his friends. Indeed, we paid little heed to what he was doing, until we observed that the rays were being used by surgeons. We were interested at once, for here we could serve man.
My first experience in this connection was quite interesting. A young girl had got a needle into her hand while she was playing about, and the surgeons were at a loss to know where the needle had lodged. We lost no time in producing X-rays which could penetrate the flesh of the hand, and reach the fluorescent screen on the other side. The bones of the hand blocked the way of our rays, but not so completely as the needle did. Hence we produced upon the screen a faint shadow of the flesh of the hand, a much deeper image of the bones, and a black shadow of the needle. This enabled the surgeon to see where the needle was hiding.
Sometimes we were called upon to produce rays for detecting bullets in the flesh, or for showing the nature of a fractured bone. We were never surprised to find that our call was to detect a coin in the throat of a child, but in this connection a big surprise awaited some of us. I was not one of the party, but I have the information from some fellow-electrons.