WORK OF SCIENTISTS

Evening Post, Volume CXXVIII, Issue 93, 17 October 1939, Page 7

WORK OF SCIENTISTS

RECENT DISCOVERIES

THE ATOM AND THE WEATHER

The discovery by several investigators in different countries that atoms of uranium explode when penetrated .; by neutrons has brought the control of atomic energy for human purposes , nearer, writes the scientific correspondent of the "Manchester Guardian.** F. Joliot, of Paris, has shown that when a uranium atom is exploded by an incoming| neutron three- or four fresh neutrons are released, in the (explosion. It may be possible to arrange that these four fresh neutrons will explode four more uranium atoms, and that the sixteen neutrons from their explosions will explode sixteen more uranium atoms, and so on. In this way a chain of exploding atoms in a lump of uranium might lead to an enormous output of energy in a short time. The arrangement seems simple, and some of the greatest authorities believe that almost inexhaustible sources of atomic energy for scientific and industrial purposes may ultimately be released by it. But no practicable quantity of energy has as yet been obtained. 'Ths'' nuclei of the uranium atoms must be' packed with a certain degree of closeness before the chain effect can de» • velop, and the quantity of uranium must be sufficient for the number of atomic explosions to become large in a short space of time. Again, the chain effect must spread more quickly than the first big explosion, which might disperse the remaining uranium into harmless dust or vapour. The end of the world is not at hand, but the large-scale release of atomic energy is now a subject of serious research and discussion. WEATHER AND THE SUN. Conditions on the earth are largely determined by the sun. Its heat and light control the development of living things and the weather. It is natural to look for the control of weather change in solar radiation. This was assumed to be constant C. G. Abbot, of the Smithsonian, Institution, now describes: in "Nature" how careful measurements/ during .the last forty years of the radiation emitted from the sun show that this is hot true. He believes that these observations prove that solar radiation,varies by about 0.7 per cent, in periods of about twenty days. Careful analysis shows that several periodicities appear, 7 in the' variation, and one of these is 274 months or twenty-three years. Now some meteorologists have noticed 23----year periodicities in climate, and this period is about twice "that* of..the! sun-' spot cycle. Periods of this length; hava been noted in the thickness of treerings and in the geological deposits of former ages. Abbot states that droughts occur at 46-year arid 96-year intervals, and concludes that the ten-year drought in the Western United States is just ; concluded, but will recur in 1975; and with excessive severity in 2021. He has succeeded in giving a good general prediction of the weather in Dakota in 1934-38, based on the records of fortysix years ago. ; COSMIC RAYS. The marvellous developments of fesearch on cosmic rays cohtiiiue without abatement. When one of the swift particles enters the upper atmosphere it produces a cascade shower of secondary particles which gradually broadens on the journey downwards. If two counters are placed a few inches apart, they will click simultaneously as different particles from the same shower go through them. The simultaneity of the . clicks shows that both particles were.., due to the same original particle enter- ' ing the atmosphere. It is evident that if the counters are moved apart they may be used to measure the width of a shower. P. Auger, of Paris, has described in the "Journal de Physique" experiments with counters seventy-five yards apart .on the Pic dv Midi, andfinds that numbers of simultaneous b clicks occur in them. v Thus enormous , showers of particles at least seventyfive yards wide are produced'; by. brie particle entering the upper atmosphere. The energy of this original ;, cosmic ray must be at -least one thousand million million electron volts, and many times greater than that produced by the annihilation'; of y matter. Thus these cosmic rays must be produced by something more energetic even than concentrations of atomic energy, or atomic explosions, and they are not as it were, rays from X the birth of matter. DIAGNOSING STONE. The stones -which afflict patients suffering from kidney trouble consist of calcium oxalate or calcium; phosphate. Successful treatment depends on the recognition of the sort'of stone? which is being formed. This may usually be done by chemical analysis, but in many cases the stones are very small, and chemical methods are not convenient. W. G. Burgers has: described in "Philip's Technical Review" how a rapid diagnosis may be made with X-rays. A minute quantity of a powdered stone is examined with Xrays, and the picture depending on its atomic structure is obtained. This may be compared with a similar picture made from powdered calcium oxalate or phosphate, and similarity will reveal at once the type of stone.