“Well, what we want to do is to start the non-radioactive elements ticking. We are looking for the right kind of shake to give them in order to start them off. If we can find that, then we shall get all the energy we need, because we can utilise enormous quantities of material where now we have only the traces of radioactive stuff.” “A risky business,” said Nordenholt. “Your first successful experiment will be rather catastrophic, won’t it?” “Probably. But I’ve left full notes of everything I’ve done, so someone else will be able to continue if anything happens to me. “Well, the real trouble is that it takes a lot to shake up the internal machinery of an atom. Rutherford did it long ago by using a stream of alpha-particles from radium to smash up the nitrogen atom. That was in 1920 or thereabouts. You see, we have no ordinary force intense enough to break up atoms of the stable elements; we have to go to the radioactive materials to get energy sufficiently concentrated to make a beginning. “Now, what I have been following out is this. Perhaps I can show you it best by an experiment. Can you get me some safety match-boxes?” A dozen of these were brought, and he stood them each on its end in a line. “Now,” he continued, “it requires a certain force in a blow from my finger to knock down one of these boxes; and if I take the ten boxes separately, it would need ten times that force to throw them all flat. But if I arrange them so that as each one falls it strikes its neighbour, then I can knock the whole lot down with a single touch. The first one collides with the second, and the second in falling upsets the third, and so on to the end of the line. “Well, that is what I have been following out amongst the atoms. I know that the alpha-rays of radium will upset the equilibrium of other atoms; and what is wanted is to get the second set of atoms to upset a third and so forth. Hitherto I have not been able to hit upon the proper train of atoms to use. Somehow it seems to sputter out half-way, just as a train of powder fails to catch fire all along its line if one part of it isn’t thick enough to carry the flame on. But I have got far enough to show that it can be done. It’s rather pretty to follow, if one has enough imagination to read behind the measurements. You really must come and see it, Nordenholt.” “Do you think it will come out soon?” asked Miss Huntingtower. “Sooner or later, is all one can say. But it might come any day.” Nordenholt rose from the table. “I’ll come across now, if you can let me see that experiment,” he said. “I’m more interested than I can tell you; and I want to discuss some points with you. I’m taking the evening off anyway, and I may as well make myself useful. How long will it take--an hour? All right. Flint, will you amuse Miss Huntingtower till I get back?” He and Henley-Davenport went out, leaving us to return upstairs.