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then, in spite of these further complexities, the mechanical aspect of the body can still no more be ignored than can the prime mover of a loom producing the most wonderful and artistic textiles. For good or ill, that machine has as much or little a right to be considered the man as his soul or brain. The attempt to amputate the spiritual from the physical world paralyses both.

The mechanistic notion of life, the representation of the body as primarily and fundamentally a machine, is often bitterly and not very intelligently opposed. We are told that the machine--the scientist's imitation of life is not merely a purely inanimate mechanism. In its cunning combination of valves and regulators it has a brain, part of the brain of its designer. The partial likeness is that of the machine to the man, of the limited imitation to the original ; not the other way about, which is true enough. But let us bear in mind one essential and undeniable fact. Machine or man, inanimate mechanism with the mechanical imitation of a brain, or brain controlling an animate mechanism, what of the power? The power to live, the power to do work, is not in the brain nor in the body, not in the valves nor the moving parts. The power, whether of life or of mechanism, is external. That is the real ground of the analogy.

Inanimate energy, which before ran to waste or lay in the ground unused, began to be guided by human intelligence and shaped for human ends. What this energy can do for good and evil the world is everywhere now the witness. Primitive man froze on the site of what are now coal mines, and starved within the sound of the waterfalls that now are working to provide our food. The energy was there, the knowledge to utilise it was not. So while we are leading cramped lives and fighting among ourselves,

THE ORIGIN OF COSMICAL ENERGY

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whether in peace or war, for a modicum of the means of existence, science tells us that, in the commonest materials that make up the framework of the world, there is energy of a magnitude of which we have no experience, and the means of livelihood upon a scale of which we have no standard. The energy is there. The knowledge that can utilise it is not-not yet.

If the nineteenth century is destined to be remembered in history on account of the establishment of the doctrine of energy, to the twentieth, young as it still is, belongs the credit of elevating and extending that doctrine to the extent that makes it of universal human interest. One simple question concerning the source of energy the nineteenth century quite failed to answer. Divorcing from the problem everything but its purely physical aspect, and putting it in its widest form, there remained unanswered the problem of its origin. How is it that the world is not yet grown old and "dead," though geologists dispute among themselves whether its history, in much the same condition as at present, can be traced back a hundred million or a thousand million years? Or, look up on a clear night at the same stars as those that greeted the gaze of the cavedweller and the mastodon when man was young. How can nature, the bank-teller, account for such a large expenditure of energy, over so prolonged a period, without long ago having become bankrupt? The sun and stars do not burn coal. Even if they did, Lord Kelvin computed that the combustion of a mass of coal the size of the sun would only suffice for 5000 years of the present rate of output of solar energy. Though, without any new source of energy, it was found by him to be possible to account for solar radiation over a period of some millions of years, the claims of the geologists for hundreds or thousands of millions could not be satisfied. What

is the origin of the stream of energy pouring out into space from stars so numerous that every living person in the world might claim a separate one as his own? That is the problem that has stared us in the face since we began to understand the laws of energy, an academic problem, perhaps, until it is realised that it is necessary for us to be able to get our hands on the levers controlling the primary sources of energy, or, when our fuel supplies are exhausted, relapse into barbarism.

At the close of the nineteenth century an extraordinary series of discoveries in physics and chemistry put into our hands a scrap of a material called radium, which asked us precisely the same question as the stars, but at point-blank range. It is a new element discovered by M. and Mme. Curie in a uranium containing mineral, pitchblende. It possesses the outstanding property of emitting energy, in relatively large amount, and in new and surprising forms, spontaneously and continuously. All we have learned of this new property, radioactivity, shows that this steady emission of energy is going on in the rocks, from which the radium is extracted, at precisely the same rate as from the radium after it has been extracted, and has been going on for hundreds of millions of years. The explanation follows from the discovery that these radioactive elements are undergoing slow changes into other elements, changes of precisely the same kind as the alchemist sought to effect when he strove in vain to transmute the base metals into gold. Modern chemistry is unable to achieve such changes, but they are now known to be going on slowly and spontaneously in the radioactive elements. We can at present only watch and follow them. We have not yet succeeded in interfering with them or quickening their rate.

RADIOACTIVITY AND TRANSMUTATION

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Hitherto in the chemical changes, from which the world derives its chief supplies of energy, such as the combustion of fuel, different elements, such as carbon and oxygen, combine together but do not suffer any intrinsic or fundamental alteration. The compound formed, carbon dioxide, can be decomposed by the chemist to give back again the original carbon and the oxygen, not entirely different elements. In other cases, the decomposition of certain compounds may give rise to the evolution of energy. Examples are to be found in all the modern high explosives, such as gun-cotton, nitroglycerine (dynamite), picric acid (lyddite), and trinitro toluene (T.N.T.). But in no case, except in the radioactive elements, has a veritable transmutation of one element into others been observed.

We have obtained evidence, in consequence of these new discoveries, that in the atoms of matter exists a store of energy beyond comparison greater than any over which we have obtained control. In the slow changes of the radioactive elements there is known to be an evolution of energy nearly a million times as great as has ever been obtained from a similar weight of matter before. The energy is there, but the knowledge of how to liberate it at will and apply it to useful ends is not -not yet.

The problem will be solved when we have learned how to transmute one kind of element into another at will, and not before. It may well take science many years, possibly even centuries, to learn how to do this, but already the quarry is in full view and, by numerous routes, investigators are starting off in hot pursuit. We need only recall the past history of the progress of science to be assured that, whether it takes years or centuries, artificial transmutation and the rendering available of a supply of energy as much

beyond that of fuel as the latter is beyond brute energy will be eventually effected.

It is unlikely, but not impossible, that such a discovery might be made almost at once. A magnificent scientific achievement it would be, but, all the same, I trust it will not be made until it is clearly understood what is involved. Let us suppose that it became possible to extract the energy, which now oozes out, so to speak, from radioactive materials over a period of thousands of millions of years, in as short a time as we pleased. From a pound weight of such substances one would get about as much energy as would be obtained by burning 150 tons of coal. How splendid! Or a pound weight could be made to do the work of 150 tons of dynamite. Ah! there's the rub. Imagine, if you can, what the present war would be like if such an explosive had actually been discovered instead of being still in the keeping of the future. Yet it is a discovery that conceivably might be made to-morrow, in time for its development and perfection for the use or destruction, let us say, of the next generation, and which, it is pretty certain, will be made by science sooner or later. Surely it will not need this last actual demonstration to convince the world that it is doomed, if it fools with the achievements of science as it has fooled too long in the past. Physical force, the slave of science, is it to be the master or the servant of man? The cold logic of science shows, without the possibility of escape, that this question if not faced now can have only one miserable end.

From time immemorial man has boasted and gloried in his physical prowess. He was a rude animal, whose turbulent experience has preserved, as a religion, this pride in force as the ultimate arbiter. Christianity for two thousand years has inculcated the opposite creed, but, while largely

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