New Zealanders and Science
9 — Rutherford
Ernest Rutherford was born at Spring Grove, Nelson, on 30 August 1871. He was the fourth son of the marriage of James Rutherford, flaxmiller and small farmer, who had arrived in Nelson at the early age of three in April 1842, and of Martha Thompson, an accomplished schoolteacher who had arrived in New Plymouth, also at an early age, in 1855. The boy attended the primary schools at Foxhill and Havelock, at the latter winning a Marlborough Education Board scholarship at the age of fifteen. This enabled him to study at Nelson College, where he proved himself a first-class all round scholar, with special aptitude for mathematics. His English master credited him in a term report with 'a retentive memory, and a great power of reproduction.' He won a University Entrance scholarship in 1889 which led him to Canterbury College.
At least until he found his feet at Canterbury College, this boy was just the healthy, normal country youth, a little better than his companions at lessons, page 94and about the average in football, swimming, milking cows, painting the house, and weeding the garden. Nothing of the infant prodigy appeared in his studies, habits, dress, or build. The great thing in his favour was a heritage common to most of the youth of New Zealand in 1890, namely a healthy upbringing in country surroundings, and descent from strong, intelligent parents of good pioneer stock. He was always tall and big-framed, and made a solid Rugby forward in his college days.
At Canterbury College Rutherford came under the influence of those two great professors, Cook and Bickerton, to whom long after he publicly acknowledged his debt when thanking the board of governors of Canterbury College for congratulations on the award of the Nobel Prize. 'If there is any credit,' he wrote, 'to be apportioned for winning a Nobel Prize, I think that Canterbury College may take a fair share; for it was there that I was well trained in mathematics by Professor Cook, and in physics by Professor Bickerton. Both were excellent teachers, and Professor Bickerton's genuine enthusiasm for science gave a stimulus to me to start investigations of my own. I have a happy remembrance of my old College days, and of my first researches in the basement of one of the lecture rooms. I learnt more of research methods in those first investigations, under somewhat difficult conditions, than in any work I have done since. I may mention that the Nobel Prize was awarded to me in page 95chemistry, and not in physics. I was rather startled at first at my sudden transformation, but the work I have been engaged in for the last ten years may be called physics or chemistry at will.'
While at Canterbury College Rutherford gained a senior university scholarship in mathematics, and graduated M.A. in 1893 with double first-class honours in mathematics and physical science. He then returned for a fifth year to study for a bachelor of science degree and to continue his researches. He became interested in Hertzian waves and set himself the task of finding a suitable detector for them. He set up a Hertz oscillator in a 'miserable, cold, draughty, concrete-floored cellar, which was usually known to the students as the "den" and in which they were accustomed to hang up their caps and gowns.' He submitted the results of this investigation in a thesis for the 1851 Exhibition science scholarship. The scholarship was actually awarded to J. S. Maclaurin, the brilliant Auckland chemist, afterwards Dominion analyst, but as the latter became ineligible owing to his marriage, it was awarded to Rutherford.
The scholarship took Rutherford to Trinity College, Cambridge, where he worked as a research student under the celebrated J. J. Thomson at the Cavendish laboratory. Rutherford followed his professor in the study of the structure of the atom and of the radiations from radio-active bodies.
It may be interesting to digress a little here and to page 96trace the conception of the atom through the ages, until the end of the nineteenth century when the work of Pierre and Madame Curie, Becquerel, Geiger, Thomson, and Rutherford, to mention only a few of the distinguished investigators, revolutionised our ideas of the structure of matter. So much has been accomplished in the last fifty years that we are inclined to forget how little was known before them.
The atom is no new conception. As early as 400 b.c. Democritus and his Greek school believed that all matter—vegetable, animal, and mineral—was composed of very minute, ultimate particles, built up in varying combinations. Lucretius in his De Rerum Natura (about 58 b.c.), a long poem Concerning the Nature of Things, reiterated this belief at some length. In the translation by William Ellery Leonard (Everyman's edition), a few lines run thus:
Are partly primal germs of things, and partly
Unions deriving from the primal germs.
. . . . .
for the same
Primordial seeds of things first move of self,
And then those bodies built of unions small
And nearest, as it were, unto the powers
Of the primeval atoms, are stirred up
By impulse of those atoms unseen blows,
And these thereafter goad the next in size.'
Nor was Lucretius so very far mistaken.
For a long time there was little advance on the teaching of the ancients. In 1808 Dalton proposed his atomic theory by which all matter was held to be composed of atoms, each of the sixty or eighty known elements possessing a different atom. William Prout in 1815 went further. He pointed out that there were grounds for believing that the atomic weights of all the elements were exact multiples of either the atomic weight of hydrogen or half that of hydrogen. His theory, printed anonymously for fear of ridicule, was merely ignored. In the latter half of the nineteenth century the relative weights of these atoms were ascertained, and the results incorporated in Mendeleev's table of atomic weights, the atom of hydrogen being taken as unity. A symmetry observed in this table induced scientists to search for new elements where certain gaps suggested that such would be found. There matters stood in the early nineties when it was a common remark that 'all the major discoveries of science had been made.' Before the nineties were ended however, the 'electron' was found. J. J. Thomson proved in 1897 that the electron was a particle of negative electricity, very much smaller than the atom of hydrogen, roughly about one-thousandth of the mass of that smallest atom.
Working with Professor Thomson, Rutherford studied the radiations from uranium and other radioactive bodies. He invented a magnetic detector for page 98electric waves and so began what Marconi completed. This, together with his discovery that uranium gave off two types of rays, which he named alpha and beta, led to his being offered a research professorship at McGill University, Montreal, where the millionaire, MacDonald, had generously endowed a physics laboratory. There from 1898 until 1907 Rutherford worked in one of the finest physics laboratories in the world. In conjunction with Professor Soddy he conducted important investigations on the alpha particles which were to provide his work for a quarter of a century. Rutherford himself proved that beta rays were particles of negative electricity, i.e. electrons, while he and Soddy correctly surmised that the alpha rays were atoms of helium. He was able to chart the rate of the rise and decay of radium emanation, and although both Becquerel and P. Curie forestalled him in publishing this rate, yet to him and Soddy belongs 'the bold and startling theory, known as the Disintegration Theory', which underlies these changes. Every subsequent discovery in radioactivity has confirmed the laws they stated in 1902, the gist of which was that as the result of the emanation of atoms of helium and electrons, the atoms of such elements as radium and uranium were being broken down and slowly transformed into sober lead. That is, a natural transmutation of elements had been discovered.
In 1903 Rutherford published his first book, Radioactivity, embodying the results of his recent researches. page 99His work was now becoming famous. In 1903 he was elected a Fellow of the Royal Society and the next year received the Society's Rumford medal. For his work at McGill Rutherford was awarded the Nobel Prize for chemistry in 1908.
Rutherford's research work may be divided into the three periods spent at the McGill, Manchester, and Cambridge universities respectively. In 1907 he left McGill to become professor of physics at Manchester, as he felt the necessity of being closer to the centre of science. At Manchester he laboured for twelve years with a large team of workers of all nationalities attracted by his fame. This second period was associated with the discovery of the nucleus of the atom.
In 1911 Rutherford discovered that the atom consisted of a dense, minute, and positively charged centre or nucleus, round which lighter negatively charged particles (electrons) revolved as planets round a sun. The number of electrons revolving in their orbits, and the number of charges of positive electricity in the nucleus (for these must balance each other) determined the element. Thus the smallest and simplest atom, that of hydrogen, consisted of a heavy proton or nucleus round which a very light electron revolved at a relatively enormous distance. The proton of hydrogen weighed 1,845 times as much as the electron, and about 100,000 electrons could be placed across the outer diameter of the atom. The page 100ninety-two elemental atoms were found to vary from hydrogen with one charge on the nucleus and one electron, to uranium with ninety-two charges and ninety-two electrons.
The war of 1914-8 dislocated research on radioactivity in all the countries of Europe. During these years Rutherford placed himself at the service of the Admiralty. He did excellent work on hydrophones, which were so essential in the anti-submarine campaign. In 1917 he headed a mission to the United States in order to make that country acquainted as speedily as possible with the recent advances in antisubmarine technique. Rutherford made no money out of his valuable war services.
After the armistice he was able to return to his earlier field of research. In 1919 he conducted one of the most important experiments of his life. By bombardment with the alpha rays of radium, he drove protons out of the nuclei of nitrogen, and in so doing he unwittingly transmuted or transformed nitrogen into oxygen—the first successful attempt by man in the deliberate transformation of matter. He had smashed up the nucleus of an atom. His account of the epochal experiment was merely entitled 'An Anomalous Effect in Nitrogen'.
Towards the end of 1919 Rutherford transferred to Cambridge where he became professor in the Cavendish chair of experimental physics on the resignation of Thomson. This third period was page 101devoted to a continuation of his work in disintegrating the nitrogen atom, extending his experiments to other nuclei. Duties now multiplied around him. In 1921 he was elected professor of natural philosophy at the Royal Institution. In that year he was able to show photographs indicating the collision of an alpha particle with a proton, surely one of the most remarkable of human achievements. He found moreover that the laws discovered by Newton held good for these minute nuclei of atoms, as did the conservation of energy. For his study of the structure of the nucleus in 1922 he was awarded the Copley medal of the Royal Society, its highest honour.
The later years of Rutherford's life were extremely strenuous. He was president of the Royal Society from 1925-30, and for eight years was chairman of the advisory council of the Department of Scientific and Industrial Research in Great Britain. It was almost an obsession with him that the future of Great Britain depended on the effective use of science by industry—an obsession which perhaps reveals a trace of Bickerton's influence. He served on many committees and displayed great driving power, a sound grasp of essentials, quick understanding, and natural liveliness. In 1925 he found time to visit Australia and his home country, where he lectured in the principal cities. He was now recognised as an international figure: he lectured in most of the scientific centres of the world and attended many international science page 102conferences; he had friends among the scientists of every country and was trusted and welcomed by them all. Significantly enough, as president of the Academic Assistance Council in 1933-4, he assisted in the humane work of finding positions for German scientists evicted from their universities for political and racial reasons. Countless honours were bestowed upon him from all countries, and in 1931 he was created Baron Rutherford of Nelson, thus becoming the first son of New Zealand to be made a peer.
Despite these many activities he supervised the extensive research carried on in the Cavendish laboratory and continued his own scientific work. In 1930 he drastically revised his early book in an endeavour to bring it up to date with the latest discoveries. In co-operation with Chadwick and Ellis, he published it in a revised form as Radiations from Radioactive Substances. In 1932, an exceptional year for physics, Chadwick at the Cavendish laboratory discovered the neutron, which is like a proton without any electric charge. This discovery had been forecast by Rutherford in 1921. In the same year, 1932, Rutherford himself with two research assistants, Cockroft and Walton, hurled protons with a voltage exceeding 600,000 at lithium, and the lithium split violently into two fragments, each helium. World attention was focused on the work at Cambridge.
On 19 October 1937 Rutherford died suddenly after a brief illness. He was only sixty-six, and his page 103death came as a great blow to the world of science, especially as he was planning a tremendous extension in the experimental work of his Cavendish laboratory with a generous gift of £250,000 from Lord Austin. He had been a hero in what he himself called 'the heroic age of physics'. His son-in-law, Professor Fowler, paid a fitting tribute: 'Ideally equipped for directing a physical laboratory, he was capable at once of intense sustained individual research, of suggesting and inspiring with his own fire cognate researches of others over a very wide field, and, particularly in later years, of organising the teamwork required for elaborate attacks on many modern problems. His genial but dominant personality, his exacting demands for the best, the inspiration of his personal research, and the generosity with which he suggested and directed the work of his staff and students, created an atmosphere in any laboratory he directed which no one who experienced it will forget, or, alas, ever hope to meet again.'
He was buried in Westminster Abbey.