“If you begin talking about uranium-X₁ and meso-thorium-2, then I won’t understand you, and I want to know what it is all about.” “Well, Miss Huntingtower, I think I can make it plain without using uranium-X₁ or even eka-tantalum; but it’s hard that I should be forbidden to use all these fine-sounding words, eh? Isn’t it? I submit under protest. It takes away half the pleasure of telling things when one has to put them in mere vulgar English. “Well”--he had an extraordinary habit of interjecting “well” and by inflecting it in various ways, making it serve as a kind of prelude to his sentences, a sort of keynote, as it were--“Well, I take it that you know what radioactivity is. Some of the atoms are spontaneously breaking down into simpler materials, and in that breakdown they liberate an amount of energy which is immeasurably greater than anything we can obtain by the ordinary chemical reactions which occur when coal is burned or when gas is lighted. “Well, if we could tap that store of energy which evidently lies within the atom we should have Nature at our feet. She would be done for, beaten, out of the struggle: and we should simply have to walk over the remains and take what we wanted. Until the thing is actually done, none of us can grasp what it will mean; for no one has ever seen unlimited energy under control in this world. We have always had to fight hard for every unit of it that we used. “Well, there is no doubt that atoms _can_ be broken down. All the radioactive elements split up spontaneously without any help from us. But the quantities of them which we can gather together are so extremely minute that as a source of energy they are feebler than an ordinary wax vesta, for all practical purposes. “So far, so good. We know the thing can be done; but we haven’t hit on the way of doing it. Is that clear?” “Quite clear, thanks,” said Miss Huntingtower, with a smile. “Radium without tears, Part I. Now the second lesson, please.” “Well, don’t be too optimistic. There may be tears in the second part. It’s a little stiffer. The majority of the elements are perfectly stable; they undergo no radioactive decompositions; so that they give off no energy. But all the same, if our views are right, they contain a store of pent-up energy quite as great as that of the radioactive set. It’s like two clocks, both wound up. One of them, the radioactive clock, is going all the time and the mainspring is running down. You know it is going because it gives out a tick; and we recognise radioactivity by certain tests of a somewhat similar type, only we ‘listen’ for electrical effects instead of the sound-waves you detect when the clock ticks. Now the second clock, the one that is wound up but hasn’t been started, is like the ordinary element. If you could give it a shake, it would start off ticking.