September 15, 192 1] 



NATURE 



89 



matter, and to believe in anything else niakes 

 some call upon the imagination. By aid of culti- 

 vated imagmation, however, the permanently deaf 

 may appreciate something of the meaning of 

 music, and the permanently blind may apprehend 

 dimly the beauty of a landscape. So it appears 

 from the experience of Helen Keller. 



Let us grant, then, that the aether impinges on 

 us only through our imagination ; that does not 

 mean that it is unreal. To me it is the most real 

 thing in the material universe. It is not matter, 

 but it seems to be the stuff of which matter is 

 made. It holds the atoms together, and it welds 

 the cosmos into a coherent whole. It penetrates 

 the pores of matter even into the innermost re- 

 cesses of atomic structure, and it extends to the 

 furthest confines of visible space. By its aid we 

 see and analyse the nebulae at distances too vast 

 for anything but mind. Through it, too, we do 

 more prosaic things — we telegraph and we run 

 electric motors — even tramcars — guiding the 

 energy by a wire itself inert. Briefly summarised, 

 the aether is responsible for cohesion, for chemical 

 affinity, for electric and magnetic forces, for light, 

 " aye, and, as we learn from Einstein, for gravita- 

 tion too. Is there anything the aether does not 

 do? Yes, it does not convey sound. Sound is a 

 vibration in matter, not in aether, while light is a 

 tremor in aether, not in matter. We see through 

 the aether ; we do not talk through it. 



But my subject is " Speech through the ^ther," 

 speech by means of what we call empty space. 

 How can that be? How can we utilise the aether 

 -r conveyance of sound? 



Only by transmutation. The aether has long 

 been used to convey heat, yet heat is a property 

 of matter. Heat from the sun reaches the earth, 

 but it does not travel as heat. .\t the sun the 

 quiver of the particles is transmitted to the aether, 

 it spreads out as radiation, and where that falls 

 it can excite a similar quiver. The heat disappears 

 in one place, to reappear in another. It travels 

 continuously as energy, but not as heat. 



So it is with sound also. The sound-vibrations 

 must be transmuted, must be delivered up to the 

 aether to travel as radiation, and at the distant 

 station it must be received by something which 

 can transmute the energy back to sound again. 



The transmutation of heat from matter into 

 aetherial energy was effected by the atoms them- 

 selves by mechanism only partially known to us. 

 Through all the geological ages— literally from 

 -time immemorial — it has been going on. Not so 

 with sound. No trace of sound reaches us from 

 an exploding star. We see the flash ; we hear 

 nothing. To transmute sound into an aetherial 

 tremor and to change it back again into sound 

 at a distant station requires human agency. It 

 needed discoverv and invention. Discoverv and 

 invention are rife among us though handicapped 

 in their early stages by poverty and lack of oppor- 

 tunity. Only when some practical result is forth- 

 coming does that diflRculty begin to disappear. 

 Faith in the power of discovery, latent in not a 

 NO. 270;. VOL. I08I 



few of our strenuous youth, would accelerate the 

 process. Faith removes obstacles and gives to 

 genius its chance. Other nations will soon be 

 beginning to realise this if we do not. 



Great achievements are not due to one man, 

 but to a succession of workers, each passing on 

 the torch to the next. Each man's life is too short 

 for extensive achievement. The great building 

 rises, stone by stone, but it takes generations to 

 complete — nay, it is never completed. 



The long chain of discoverers has no end and 

 no specifiable beginning. One can but pick out 

 a few salient peaks. Nor is it one line only ; it 

 is a branching line. Different paths seem to con- 

 verge on some one goal. It is well to remember 

 great names of recent times — Kelvin, Maxwell, 

 FitzGerald, Hertz, the pioneers on one line, and 

 on another Crookes, J. J. Thomson, and others 

 who are working hard to-day. The first line dealt 

 with the aether and its properties ; the second line 

 discovered the nature of electricity. 



It is only with scientific principles that I am 

 dealing, not with the technical details of applica- 

 tion. Methods of application are protean ; many 

 an amateur is acquainted with them, and the 

 subject is advancing so quickly that devices a few 

 years old may hiss the speaker ; each twelvemonth 

 teems a new one ; but the fundamental principles 

 remain, and one of these is the nature of elec- 

 tricity. It has turned out to be corporeal, atomic, 

 or, rather, electronic. The discovery which closed 

 the nineteenth century was the isolation of the 

 natural unit of electricity. Small almost beyond 

 conception, mobile and active to an extraordinary 

 degree, the electron is becoming our most docile 

 servant. The skill of man has harnessed electrons, 

 and it is by their aid that sound-vibrations can be 

 transmitted to the aether, and, after transit across 

 great vasts of space, can be transmuted back 

 again. In an empty Crookes 's tube they can be 

 driven off from matter. From a hot wire they 

 evaporate, and they can be deflected and guided 

 as we wish. Their obedience is absolute and in- 

 stantaneous ; they have next to no inertia or slug- 

 gishness of their own, and they obey the slightest 

 force. An electric pole attracts or else repels 

 them, according to its sign, and so their motions 

 can be encouraged or can be checked. 



If faced with a positive plate they rush to it ; 

 if the plate is negative they retire discouraged. 

 Their journey is itself an electric current, and thus 

 we get an electric current varying and responding 

 to every fluctuating control. Electric oscillations 

 are known. We owe them to Kelvin and Fitz- 

 ■Gerald. They are of extraordinary frequency — 

 millions of vibrations f>er second — and thev 

 generate waves in the aether, as was shown by 

 Maxwell and Hertz. 



Let us, then, arrange a microphone, an ordinarv 

 telephone transmitter to which we can talk in the 

 ordinary way, and let the slow sound-vibrations — 

 a few hundred per second — be applied to 

 strengthen or weaken electric oscillations of a 

 few million per second. Thousands of oscillations 



