Rutherford and the Atom
By SIR HENRY DALE, O.M.
ON November 30th, the day of its anniversary meeting from its earliest days, the Royal Society of London launched an appeal for a fund to commemorate the life and work of the late Lord Rutherford of Nelson, whose scientific discoveries have changed, for all of us, the very manner of our thinking about the ultimate nature of the material universe.
Ernest Rutherford was born in 1871, as one of a large family, on a farm in New Zealand not far from what is now the city of Nelson, at the northern end of the South Island. His father was a farmer, lumber-merchant and flax-miller. His grandparents on both sides had been early immigrants, and the country into which he was born, then newly claimed from the wild, still demanded much of pioneering enterprise, of individual craftsmanship and opportunism, for its husbandry and for the daily life of those employed in it. The freedom of this life so near to the open country, its strenuous work, adventurous pleasures and bracing encounters with hardship, even with danger, must have played their parts :n the sound ripening of young Ernest Rutherford's great natural gifts of character and ability. He spoke often of what he owed to his parents, thought always of New Zealand as his home, and wrote every fortnight to his mother while she lived. He was fortunate in his early teachers too, and at the age of fifteen won an open scholarship to an excellent school, Nelson College. He used to say that, but for this, he would probably have been a farmer ; if such had been his destiny, it can safely be assumed that he would have been a very good one.
To the world's great gain, however, he won a scholarship from the school to the University of New Zealand, with which he entered Canterbury College, Christchurch. There, after graduation and further honours, we find him, in his fifth university year, engaged on his own initiative in an experimental research on the Hertzian (wireless) waves, then a comparative novelty. His success in con- structing, at that early date, a simple but ingenious magnetic detector of such waves was to be an important factor in the award to him of an Overseas Scholarship by the Commissioners of the 1851 Exhibition Fund. This took him to Cambridge in the autumn of 1895, as one of the first batch of post-graduate students attracted thither by the fame of J. J. Thomson. And thus he became a student of Trinity College, Cambridge, as Newton, Clerk Maxwell, Rayleigh and J. J. Thomson had been before him ; and he was soon at work in the Cavendish Laboratory, in the first instance at an extension of his researches in New Zealand on the detection of the Hertzian waves at a distance. Some of us still living, who were fellow-members with him then of the University Natural SCience Club, have a vivid memory of a meeting of the Club in his rooms, at which he triumphantly demonstrated the reception of waves from the Cavendish Laboratory, half a mile away and with many buildings intervening, when a Hertzian oscillator was put into action there at an agreed time.
Rutherford's main research activities, however, during this period as a post-graduate student at Cambridge, early took a different direction. This came from discoveries which were announced soon after his arrival there--that of the X-rays by Röntgen late in 1895, and, in the following year, of the radiation from uranium by Becquerel. At Thomson's suggestion Rutherford studied the ionization of gases by X-rays, and then oy the rays from uranium and even before he left Cambridge for Montreal he had recognised two types of radiation from uranium and called them " alpha " and " beta " rays. It meant much to the world, indeed, for future developments, that Rutherford's arrival in Cambridge and his entry there upon what was to be his life's work should have coincided with this beginning of a new era in physics ; J. J. Thomson's announcement of the electron, the first blow to wharf had so long been the accepted doctrine of atomic permanence, was made in 1897, the year before Rutherford, at the age of twenty- seven, was appointed to the Chair of Physics at McGill University Montreal.
There might have been some doubt of the wisdom of Rutherford's' moving from Cambridge at that juncture to Montreal, where he would be thrown, thus early, to a large extent on his own resources ; but any such forecast would have been very wide of the mark. His independent genius as a discoverer sprang at once into its full stride, so that, a few years later, Montreal had become the centre to which the world was turning, with an almost' incredulous expectation, as Rutherford's work, partly in conjunction with Soddy, revealed' in imposing succession the phenomena of atomic disintegration as the cause of radio-activity, and unravelled the complex chemistry of the radio-active elements. Here were shown experimental skill and resourcefulness, penetrating vision and intellectual courage, all of the very highest order ; Rutherford, in his early thirties, was already leading the scientific world into the new era of sub-atomic physics.
That leadership was by no means lost, but confirmed and extended, during his subsequent tenure of the Chair of Physics at Manchester, from 1907-1919, and then of that at Cambridge until his death in 1937. At Manchester, again by a penetrating deduction from an unexpected experimental observation, he arrived at a new picture of the atom, with a central, positively charged and heavy nucleus, and a planetary system of negative electrons. The development of this conception, with all its theoretical implications, required a brilliant mathematical achievement by Niels Bohr, then working with Rutherford at Manchester. After an interruption due to the war of 1914, Rutherford returned to his researches in 1918, and before he left Manchester he had clear experimental evidence of the transmutation of an element.
When he became Professor at Cambridge, Rutherford's researches, and those of an enthusiastic team of pupils and co-workers under his leadership, became centred on the properties and constitution of the atomic nucleus, and the effects upon it of bombardment with swiftly moving sub-atomic particles. The year 1932 has frequently been cited as the annus mirabilis of this period, when Chadwick discovered the " neutron," which Rutherford had predicted, and Cockcroft and Walton demonstrated the disintegration of the atomic nucleus of lithium, when it was bombarded with accelerated protons. Such studies were early steps on the road of discovery which led to the fission of the nuclei of heavy elements, such as uranium, and its production in explosive form as a chain reaction. Rutherford did not live to see this as an accomplished fact, though he had spoken of it as a .possibility to be viewed with disquiet. The world, faced now with the problems which it has created, may well feel orphaned by the death which deprived it so early of the guidance which his genius and his massive wisdom might have, given.
Rutherford died in 1937 at the age of sixty-six years, before we could perceive any abatement of his splendid vitality, or of the range and the penetrating power of his mind. Many still living had direct experience of the inspiration which radiated from his native genius, of the robust warmth of his comradeship and the noble simplicity of his character. Some of us, then, might feel uncertain of the impartiality of our judgement, if we tried to assign to Ruther- ford his place among the great builders of modern science. The unanimity, however, of those who, in all the world, are most competent to form an opinion seems to make it certain that history's verdict will place him among the very highest. The comparison, with Newton recurs frequently as the one which many have felt to be natural. " Rutherford's achievement . . . must surely give him place with Newton as the greatest physicists of all time," writes his pupil, Professor Dee, in a current article in Nature on the propciied memorial: " Rutherford was the Newton of the Atom," said more than one, when the news of his death broke upon the world. And in 1939 a distinguished German- scientist made the same comparison in a public lecture in London, in terms which were unlikely then to be viewed with official favour in his own country, and might even have brought him into danger. " We feel in Germany," he said, " that through the death of Ernest Rutherford the world has lost its greatest man of science since Isaac Newton."
It is no more than natural for any member of our race to feel a thrill of pride at the mention of these two together, in such a scientific supremacy ; and the Royal Society is entitled to have its particular pride in remembering both of them as having sat, at an interval of rather more than two centuries, in its presidential chair.* Their scientific achievements can properly be claimed, of course, for all mankind ; but while Newton's productive life in science, that of a sensitive recluse, belonged most intimately to Trinity College in Cambridge and then to the small England into which he was born, that of Rutherford with his large and generous nature, and by right of his birth and the successive phases of his career, belongs to the world-wide Commonwealth of Nations into which the British people have spread since Newton's day. It is most fitting, therefore, that the Royal Society should have decided to com- memorate Rutherford by a scheme, including post-graduate Ruther- ford Scholarships and a periodical Rutherford Lecture, so planned as to promote a free interchange of scientific enterprise and experience among the British Dominions, with a certain preference, in the placing of the Lecture, for Rutherford's native New Zealand. It is to be hoped that young scientists of the British Commonwealth will yet receive, from the proposed memorial fund, help as decisive for their careers as that which was given to Ernest Rutherford by the award of the Overseas Scholarship which took him as a young man from New Zealand to Cambridge.
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