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Volume 68, 1938-39
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Baron Rutherford of Nelson, 1871–1937.

The news of the death of Lord Rutherford on October 19, 1937, which came with unexpected and tragic suddenness, has caused a deep sense of sorrow and personal loss to all who knew him or who had become accustomed to rely for inspiration on his succession of announcements of major discoveries and generalisations. The magnitude of the loss was, on succeeding days, further brought home by the circumstances of his burial in Westminster Abbey and by the flood of spontaneous tributes from world leaders, which have demonstrated not only his greatness as a scientist, but the warm personal regard and esteem in which he was held universally, and the greatness and inspiration of his life as a man.

The terms customarily used in obituary notices somehow seem inadequate to the occasion; yet fortunately a memorial to his greatness already exists in his scientific writings over the past forty years, and is recorded in a manner which lesser men can neither add to nor detract from. Apart from the personal satisfactions of accomplishment arising from his own eager and unquenchable thirst for research and its results, he did not spare himself the onerous task of interpreting these results to his fellows. Each of his publications to this end bears the indelible imprint of the master, clear-cut in reasoning, leading to direct and brilliant experiment followed by a synthesis of the newly-discovered and other relevant facts, freely acknowledged when they were the work of others, to bring out a bold convincing generalisation which leaves the subject completely and comprehensively covered. Looking back over all his numerous published papers, one can find few errors which have crept into the writings and few if any conclusions which he needed to modify later. As a famous professor once said: “When Rutherford says a thing is so, there is no need to check it.” One is only left with the wonder that it should be possible for one man in a single lifetime to have accomplished so much. In fertility of mind and constructive imagination, he equalled Newton; in experimental methods and genius, Faraday; but in addition, he had an unparalleled exuberant enthusiasm for his work and a human capacity for attracting and inspiring others to work alongside him in enthusiastic co-operation and good comradeship for which the writer can bring to mind no other leader to compare.

In general, whether a man be a statesman, a philosopher, or a scientist, the position he may ultimately occupy in the view of historians or in international regard is not one which can be estimated even approximately in his lifetime. In the case of Lord Rutherford, however, his pioneering work involved such a great unfolding of Nature's truth and such a revolution in scientific thought, and ushered in an epoch of such rapid advance both in theory and application, that there is already enough perspective to appreciate his genius and work and to realise the honour done to New Zealand by its association with his birth and training. His life and work constitute one of those lights which illuminate the way down the

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The Late Lord Rutherford.

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ages towards an increased understanding of nature and which appear to emerge in the whole world only once in more than a century.

In this article, the hope and purpose is to review briefly some aspects of Rutherford's life and work, more in an endeavour to obtain inspiration and teachings for our own generation than to attempt to give his life in complete detail; much of the latter cannot for obvious reasons be written yet.

The influence of heredity and early environment in the development of genius is an interesting but still incompletely understood subject. Everyone knows that it is from their parents that children derive their bodily and mental qualities; nevertheless, parental influence is not confined to the hereditary constitution of the genes transmitted to the children, but, owing to the long association of children with their parents during the impressionable years, many acquired characteristics and habits of the parents are unconsciously handed on to the children. It is often these acquired characteristics and habits which have a profound influence on a child's career. Looking at Rutherford's origin and upbringing from this point of view we find that, while favoured with a distinctly more than average physical and mental endowment, he was even more fortunate in the qualities which he acquired from his parents and from the country environment in which he was raised. The first twenty-four years of his life, prior to leaving New Zealand, gave him an ideal equipment of physical development, health, training in all its aspects, habits of work and character which fitted him to profit to the full from the larger opportunities of university life at Cambridge to which he was so fortunate as to be called. It was these earlier influences which were of profound importance in assisting him to attain to the unique position in world science to which he rose.

Rutherford inherited high qualities from both his parents, from his father a balanced yet fertile and inventive mind and a rich physical endowment; from his mother, a very high mental equipment. In the habits and qualities he acquired from their example he was however probably even more fortunate.

Lord Rutherford's parents both arrived in New Zealand as young children nearly 100 years ago, in the very early days of the colony. His father, James Rutherford, arrived in Nelson from Scotland in April, 1842, at the age of three, while his mother, Martha Thompson, came to New Plymouth in the early fifties with her widowed mother. They were married in April, 1866, and they had in fairly rapid succession twelve children, of whom Ernest, afterwards Lord Rutherford, was the fourth. He was born at Spring Grove, between Nelson and Motueka, on August 30, 1871. The whole family possessed high mental capacity and good physique. Moreover, under the influence of their parents, they were a singularly united, happy and religious family.

Rutherford's father was a man of great character, of fine quiet disposition, straight and honourable. He was a good, ingenious and resourceful engineer. A characteristic of the father, as later of the son, may be expressed in the words of the poet: “He doeth little

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kindnesses—which most leave undone or despise.” His mother was a truly remarkable woman of high education and character, very musical, a good organiser, thrifty, and hard-working. She had a true appreciation of the value of education and had a practical ambition for her children, for in common with most of the early pioneers, the parents even in adversity denied themselves to give their family a good education.

At the age of 15, Ernest Rutherford, after attending the primary schools at Foxhill and Havelock, won a Marlborough Education Board Scholarship (value £52 10s per annum for two years), obtaining the astonishing total of 580 marks out of 600. Thus he went to Nelson College in 1894, and such was his grounding that he was immediately placed in the Fifth Form and soon justified his classification. His first headmaster was W. J. Ford, a famous English cricketer, followed by J. W. Joynt, but it was from a master, W. S. Littlejohn, that he probably gained most inspiration and particularly a grounding in mathematics. He would take long walks over the hills with Littlejohn on Saturdays, and it is said that frequently they would pause to draw diagrams on the ground with a stick to illustrate these discussions. Although Joynt has recorded that Rutherford “displayed some capacity for mathematics and physics but not to an abnormal degree and that he was a keen footballer and a popular boy,” yet he won all the scholarships and prizes available in classics, French, English and mathematics and was Dux of the College. A special characteristic was his ability to concentrate on work or play alike, as the occasion demanded. In his term report in December, 1888, when in the Sixth Form, Ford states: “He is top in every class and his conduct is irreproachable.” Joynt wrote in a later report, “One from whom one may look for good results in the future,” while Littlejohn wrote “Nunquam non paratus. Should give a good account of himself.” He won a Junior University Scholarship in 1889, coming third on the list, which was headed by Marris (afterwards Sir Charles Marris), who was later to be his friend and rival at Canterbury College, which both entered the following February.

At Canterbury he came mainly under the influence of a good Professor of Mathematics, C. H. H. Cook, and an original but somewhat unorthodox Professor of Physics and Chemistry, A. W. Bickerton. More fortunate still, there were several brilliant fellow students and the numbers were of such size that more of a tutorial system was possible. He earned a B.A. in 1892 with senior scholarship in Mathematics; M.A. in 1893 with First Class Honours in both Physics and Mathematics (then a very rare event), and B.Sc., in 1894. During this latter year he taught at the Christchurch Boys' High School as a part-time and indifferently successful teacher and also carried out researches on a magnetic detector of Hertzian waves, an account of which appears in The Transactions of the N.Z. Institute for 1894 (pp. 481–513) in a paper read before the Philosophical Institute of Canterbury, November 29, 1894. These researches were carried out on his own initiative under difficult conditions in a rough basement cellar. As source of electricity he used a battery of Grove

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cells, the box for which he constructed in his father's buggy-shed at Pongarehu while on holiday. The cells required attention each morning before he commenced work. Nevertheless, with these slender resources, he produced a very highly sensitive detector, which later held the record for distance of reception. The research was fertile in that it led to many other magnetic detectors of wireless waves and to a large number of patents, including one taken out by Marconi in 1902. Rutherford's interest in the work, however, was purely scientific. In the meantime, he spent each of his long vacations at Pongarehu, where he earned pin money by assisting on the farm or the flax operations. He painted the house, helped in the paddocking of the flax, constructed a tennis court, took long tramps in the hills shooting pheasants, and shared with his eldest brother George in supplementing the education of his sisters.

In 1894 Rutherford was a candidate for the 1851 Exhibition Science scholarship originally founded at the suggestion of the Prince Consort. There must always be difficulty in the award of this scholarship when there are good candidates offering in different subjects, and in this case the award was first made to J. C. Maclaurin, who afterwards filled so worthily the position of New Zealand Dominion Analyst. For family reasons Maclaurin was unable to take up the scholarship, which was accordingly awarded to Rutherford, who left for the University of Cambridge in 1895. He wisely entered Trinity College and the Cavendish laboratory to work under Professor J. J. Thomson, then at the height of his powers. In the interval of uncertainty regarding the scholarship Rutherford had accepted a teaching post at New Plymouth High School, although definitely with the idea of saving up enough money to finance a course at a British university. He entered Cambridge University as one of the first students to be admitted under a new regulation admitting as research students graduates from other universities.

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Rutherford started work at the Cavendish Laboratory in October, 1895, and he at first devoted himself to improvements of his radio detector; but he had not worked there more than a few weeks before he had convinced his professor that he was a student of exceptional ability and energy, and the story went round that there was a “young rabbit from New Zealand who burrows very deep.” However, a remarkable combination of circumstances caused him to change his line of work. J. J. Thomson and his fellow workers had for ten years been engaged on the problems associated with the passage of electricity through gases in a partially evacuated chamber. These experiments had indicated that electricity was transferred through such gases mainly by particles termed electrons, generated within the chamber, and which appeared to be of the order of 1/1800 part by weight of the atom of hydrogen. In November, 1895, i.e., a month after Rutherford had gone up to Cambridge, Röntgen had made the astounding observation that when electricity was passed at high voltage through such a chamber with a high degree of vacuum, invisible rays were given off which had the power of passing through the glass walls of the vessel and also through outside opaque objects and of affecting a photographic plate. These rays, called Röntgen-

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rays or X-rays, were soon found by J. J. Thomson and others in France and Italy to have other interesting properties in that they made the outside air electrically conducting. Rutherford's attention was attracted to this astonishing phenomenon and he commenced work on it with Thomson, who describes the work as follows:— “Rutherford devised very ingenious methods for measuring various fundamental quantities connected with this subject, and obtained very valuable results which helped to make the subject ‘metrical,’ whereas before it had been only descriptive.”

J. J. Thomson and Rutherford published their results in November, 1896, in a paper entitled “On the Passage of Electricity through Gases exposed to Röntgen-rays.” This paper is the foundation of the ionisation theory of conduction of electricity through gases. Interestingly enough there is no reference to the word “ions” or “ionisation” in the whole paper, although gradually there is developed in the paper from the experimental results described, the whole idea of “charged particles” produced by the radiation, their movement under an electric force, their properties of diffusion, recombination and mobility, and the idea of a saturation current as opposed to the ordinary conception of an electric current obeying Ohm's law. This and two succeeding papers on the same subject by Rutherford himself naturally attracted wide attention among physicists; the ideas were at the time so novel that Rutherford in this short interval came into the limelight. Moreover, Becquerel had in the meantime (1896) discovered that uranium and its salts also emitted radiations which like Röntgen-rays were capable of affecting a photographic plate and discharging charged bodies in the neighbourhood. This was the start of the subject of radioactivity, this name being coined by Mme. Curie, who with her husband used this property to isolate radium and polonium from a uranium ore, pitchblende, in 1898.

After the announcement of the radioactivity of uranium, however, Rutherford applied the knowledge and technique of his work on Röntgen-rays to the investigation of the radiation from uranium and thorium, and in 1898 he had completed a masterly analysis giving incidentally a complete verification of the ionisation theory that had originated from his previous experiments on Röntgen-rays with J. J. Thomson. The most important result, however, was that the radiation from uranium was found to consist of an easily absorbed portion which he termed α-rays and a more penetrating fraction which he termed β-rays. The existence of the still more penetrating γ-rays was discovered later. It was these α-rays (or doubly charged atoms of helium as he afterwards showed them to be) which seemed to have a special appeal to Rutherford during the rest of his life and later proved so effective as a tool in unravelling so many atomic secrets.

It is small wonder therefore that when Cox came over from Montreal in 1898 in search for a successor to H. L. Callendar for what was virtually a purely research professorship at McGill University, his inquiries inevitably led him to Rutherford, who ultimately accepted the position. The salary was not large, £500

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per annum, but Rutherford stated at the time that the chief attraction was the research facilities available through the munificence of Sir William Macdonald. It is worthy of noting that Sir William Mac-donald continued to provide Rutherford with that special apparatus and material, e.g., liquid-air machine, radium, etc., without which much of the glorious story of his achievements would have been impossible.

The year following his appointment he visited New Zealand to marry Mary Newton, to whom he had been faithful since early in his Canterbury College days. She was a very capable, practical woman with a high sense of duty, a keen suffragette and a temperance advocate. She made him a good wife, her house was well run and was always open to his colleagues, research students and visitors from overseas. In the early days of their marriage, particularly, she typed his papers, edited them, helpfully criticised from the layman's point of view his various addresses and particularly his first books on radioactivity. They had only one child, Eileen, a vivacious personality, born the year following their marriage. Her death in 1930 was to Lord Rutherford a very severe loss. She was married to Professor R. Fowler, F.R.S., and four bright children have survived her.

To return to Rutherford at McGill: although at first without the association of those with direct knowledge of his subject, apart from the helpful correspondence of Sir J. J. Thomson and Sir Robert Ball, he quickly settled down to work and attracted to himself many co-workers both from Canada and overseas, for he was far from being a recluse. He “radiated” enthusiasm, interest and will to co-operate. His first experiments related to the nature of the radioactivity of thorium. He noticed that the conductivity of the air, produced by some compounds of thorium and particularly the oxide, varied in a most erratic manner. This phenomenon was traced to some gaseous substance given off from thoria, which could be carried away in a gas stream. He gave the name emanation to this unknown substance. He also noticed that all substances remaining in contact with the emanation themselves became radioactive. This excited radioactivity decayed with time, falling to half-value in eleven hours, whereas the emanation itself decayed to half-value in one minute. Thus was born the idea of successive radioactive transformations, and in association with Soddy, who undertook the chemical work, he proceeded to investigate the nature of the various known radioactive substances. Together they discovered thorium X, etc., showed that each radioactive body in the series had different chemical and physical characteristics, and that the gaseous emanation could be liquified and had all the properties of an inert gas of high atomic weight. The great contrast in the physical and chemical properties of these elements, and the exact measurements they carried out, led to their enunciation in 1902 of the bold and startling theory known as the Disintegration Theory of Radioactivity, which embodied the idea of successive radioactive transformations. According to this theory atoms were no longer regarded as permanent, everlasting, and indivisible. Radioactive elements disintegrated spontaneously. They

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broke up according to the laws of chance independently of age or their physical or chemical state or surroundings. The mortality rate was constant for any one radioactive substance, but varied widely from one type of atom to another. In each case the disintegration took place with liberation of a large amount of energy which showed itself either by the ejection of an α-particle or a β-particle. Ruther-ford showed the α-particles to be positively charged and the β-particles negative. From his measurements he deduced that the former were probably atoms of helium, and the latter electrons in swift motion. He also showed that the energy of the α-particles accounted for the spontaneous production of considerable heat by radium. It is perhaps difficult for us to now appreciate fully the revolution in ideas involved in his results and conclusions; even Kelvin was hard to convince.

Rutherford was elected to the Royal Society in 1903 and delivered the Bakerian Lecture in 1904, when he outlined the whole science of radioactivity in a masterly comprehensive study. He travelled to many American universities to give lectures on his subject and received numerous offers of important posts which would have been to considerable financial advantage. He valued facilities and equipment much more highly than money, however, and he was not desirous of changing his nationality, feeling confident that sooner or later a suitable British post would be available to him. This eventuated in 1907 when that brilliant physicist Professor Schuster wrote offering to retire from the Chair at Manchester if Rutherford would take the post.

The subsequent rapid developments are perhaps best illustrated from Rutherford's own words at the presentation to him of the Franklin medal in 1924:—

“In 1907 I left McGill to take the post of Professor of Physics in the University of Manchester, vacated by Professor Schuster. Before leaving Montreal, I had been much interested in the discovery made independently by the late Sir William Crookes and Professor Giesel that the α-rays produced scintillations in phosphorescent zinc sulphide. There was no reason at that time to believe that each α-particle produced a scintillation, but the discovery directed my attention to the importance of finding a method of detecting a single α-particle and of counting the number emitted per second by one gram of radium. Preliminary calculations showed that the ionization current in a gas due to a single α-particle might produce sufficient effect to be detected by a very sensitive electrometer. Doctor Geiger and I attacked this problem experimentally but without much success. It then occurred to me that the electrical effect might be greatly increased by utilizing the property of ionization by collision in a strong electric field. After some disappointments, this method proved successful and we had the satisfaction of showing that individual α-particles could be easily counted by this electric method. This allowed us to determine the number emitted per second by one gram of radium, and, by measuring the positive charge carried by the α-rays, we were able to obtain a fairly accurate value of the fundamental unit of charge, viz. 4.65 × 10-10, while later precision methods gave 4.80 × 10-10 electrostatic units.

“At this stage, the evidence as a whole strongly supported the view that the α-particle was a doubly charged atom of helium, but it was of great importance to settle this question definitely by a straightforward method. For this it was necessary to collect the α-particles and to show that they gave rise to helium, quite independently of the radioactive matter from which they were expelled. This might be done if a glass tube could be constructed sufficiently strong to contain a large quantity of radium emanation but so thin that the α-particles could be fired through it. I put the problem of the construction of such a tube to Mr. Baumbach, a skilful glass-blower attached to the

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University. After a few hours' trial, he produced the first α-ray tube of glass. With this I was able to prove definitely that the α-particles which had been fired from this tube into the walls on an evacuated glass receiver, after diffusing out, gave the complete spectrum of helium.

“Unless I am to take too much of your time, I must confine myself to only a few more points of special interest. I have always, since the discovery of the nature of the α-rays, had a great interest in this type of radiation, and I will now show the steps by which the α-rays were utilized to probe the inner structure of the atom and to throw light on its constitution. In our experiments on counting α-rays by the electric method, we had been troubled by the scatterings of α-rays in passing through matter. Doctor Geiger made a special examination of the average scattering for small angles of reflection. I suggested to one of my Manchester students, E. Marsden, that it would be of interest to examine whether any α-particles were scattered in the backward direction from a metal plate. I did not have any reason to expect a positive result, and Doctor Geiger and I were very surprised when a considerable number of α-particles were found to be scattered through an angle of more than 90 degrees. From Geiger's experiments on the average angle of scattering by metal foils and from the laws of multiple scattering, we could not expect a detectable number of particles to appear in the backward direction. Both Geiger and I appreciated at the time that this was a very strange and remarkable result, difficult to reconcile with existing views of atomic structure. After a number of calculations, I came to the conclusion that this large angle scattering could only be explained if there were intense electric fields in the atom, due to one or more massive charged centres, and that the large deflections were produced by a single collision with such a centre. From this arose the conception of the nuclear constitution of the atom, an account of which was first given by me in 1911. The theoretical laws of scattering on this assumption were very completely verified by the careful measurements of Geiger and Marsden, published in 1913.”

The foregoing takes us to the third great epoch-making advance associated with Rutherford. The first was the Ionisation Theory of conduction of electricity through gases, the second the Disintegration Theory and the third the Nuclear Theory of Atoms. In this latter theory the atom is pictured by Rutherford as a miniature solar system, beautiful in its simplicity. The nucleus or central sun had an aggregate of positive electricity, while the corresponding number of (negative) electrons occupied closed orbits round the nucleus similar in some respects to those of the planets round the sun. The charge on the central nucleus and the number of “planets” determined the kind of chemical atom involved.

At this time Rutherford had among other brilliant co-workers in Manchester, Moseley and Niels Bohr, whose work each in his own field verified and extended Rutherford's conception of the nuclear atom. If the nuclear constitution of the atom was correctly conceived, neither the stability nor the modes of vibration of the electron, for example in hydrogen, were explicable on the ordinary classical theory. A radical departure from accepted views seemed essential. This departure, made by Bohr, consisted in a novel application of the ideas underlying Planck's Quantum Theory of Radiation. Bohr's theory applied to the Rutherford atom was triumphant from the first; he not only deduced the nature of the spectrum of hydrogen, but explained the existence of the Pickering and Fowler spectral series and showed that instead of being part of the hydrogen spectrum they were almost certainly due to ionised helium, a prediction which was verified. Moseley, on the other hand, by measuring the X-ray spectra of the elements was able to show that the nuclear charge

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of an element was in numerical units given by its ordinal number and that the properties of an element in the periodic table were practically solely dependent on a whole number representing the nuclear charge: one for hydrogen, two for helium, three for lithium, and so on up to 92 for uranium. These theories simplified the whole conception of the relation of chemical and physical properties of successive elements and led to the extraordinary conception of isotopes, i.e. elements with the same nuclear charge and same chemical and physical properties, but with different atomic weights. The atomic weight was shown to be of minor significance compared with the nuclear charge or atomic number.

We must now pass on to Rutherford's next great deduction and discovery. In a collision between an α-particle of mass 4 and the nucleus of an atom, the ordinary laws of conservation of momentum might be expected to apply; and thus if the nucleus of an atom of hydrogen of mass 1 were encountered in direct hit by the α-particle, the former might be expected to be set in motion with a speed much in excess of the incident heavier particle. Thus the present writer established the occurrence of the swift-moving hydrogen nuclei afterwards named protons. It was found, however, that protons were produced when α-particles were fired into ordinary air. Much time was spent in making sure that the effect was not due to adventitious hydrogen associated with the source of α-particles, and Rutherford, repeating the observations during the war period, noted that many more protons were observed in dry air or nitrogen than in dry oxygen. This led Rutherford to the discovery that the protons were generated in nitrogen, the nuclei of whose atoms were disintegrated artificially by close impact with a high-speed α-particle, with the eventual production of an atom of oxygen and a hydrogen nucleus. In subsequent work at Cambridge, Rutherford and Chadwick were able to show that not only nitrogen but also boron, fluorine, sodium, aluminium and phosphorus are disintegrated by α-ray bombardment with the emission of hydrogen nuclei. Thus was accomplished the artificial disintegration and transmutation of elements, the dream of the alchemists of old.

Here it may be mentioned that immediately after the war Sir J. J. Thomson retired from the head of that most famous laboratory, the Cavendish Laboratory at Cambridge, and Rutherford was selected to succeed him. The Cavendish Laboratory was built in 1874 in honour of the Cambridge scientist Henry Cavendish. Its chief founder and first director was James Clerk Maxwell, whose mathematical theory linking up electricity, magnetism and light paved the way for the discovery of radio telegraphy and telephony. Maxwell died in 1879 and was succeeded by Lord Rayleigh, who resigned in 1884 in favour of Professor J. J. Thomson. Thus each of the four succeeding directors of the Cavendish Laboratory has been internationally famous, Rutherford not the least.

To return to our review of atomic transformations: as time went on and the mechanism of these transformations was more understood, new types of radiation were discovered, e.g. the neutron in 1932 by Chadwick (already prophesied by Rutherford). As a result

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a very large number of artificially produced radioactive bodies have been isolated not only by bombarding elements with α-particles, but also by bombarding with fast protons, neutrons and deuterons. The next advance was to devise electrical methods of speeding up ions to such a velocity that they could be used for the purpose of producing artificial disintegration of other elements, i.e., the use of streams of particles produced and controlled at will in the laboratory. The pioneer experiments in this field were carried out in Rutherford's laboratory at Cambridge by Cockcroft and Walton, but great developments followed elsewhere, particularly in U.S.A. Costly apparatus on an engineering scale is involved, together with large specially constructed buildings. The availability to Rutherford and his assistants of such facilities was arranged just prior to his unfortunate death, thanks to the magnificent gift of £250,000 by Sir Herbert Austin. In his letter to Earl Baldwin, Chancellor of the University, transmitting the offer, the donor stated:—

“I have for several years been watching the very valuable work done by Lord Rutherford and his colleagues at Cambridge in the realm of scientific research, and knowing that as Chancellor you are keenly interested in obtaining sufficient funds to build, equip and endow a much-needed addition to the present resources. I shall be very pleased indeed to present securities to the value of approximately £250,000 for this purpose.”

The comments of Austin and Rutherford in the Morning Post are perhaps more significant. Austin stated:—

“By contrast with American scientific institutions those in this country have been poorly provided with the material means to prosecute research; in particular I know that the Cavendish Laboratory has been handicapped in some of its work by lack of the equipment available at various American centres. The fact that it has none the less held its position is the finest possible tribute to the men who work there.”

Rutherford said with characteristic modesty:—

“I am very gratified at the very generous gift of Sir Herbert Austin and the recognition of the important work that has been done in the past by Sir J. J. Thomson and his colleagues at the Cavendish Laboratory. The first use of the money will be to build a laboratory for the utilisation of very high voltages in order to carry out experiments on the transmutation of matter by high speed particles and by radiation.”

Thus, although his life was not incomplete either as an entity or an achievement, yet as Sir J. J. Thomson said: “His death, just on the eve of his having in the new High Tension Laboratory means of research far more powerful than those with which he had already obtained results of profound significance is, I think, one of the greatest tragedies in the history of science.” Others are bearing and will carry the torch; the world will reap the benefits. The personal influence of Rutherford and the direct impetus of his work will long continue to be felt. The example of his life and work will be the inspiration for generations yet unborn.

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Rutherford seldom, in his public utterances, strayed from the scientific subjects in which he was particularly qualified and interested, though he would discuss world and economic affairs with his intimate friends, bringing to the discussion a shrewdness and breadth of vision which showed him to be an unbiassed and keen observer of world movements. In this latter connection, however, it is interesting to quote from the Norman Lockyer lecture delivered only a year before his death:—

“In the present state of industry, when progress and change are rapid, it seems to me that it would be an advantage to the State to know the probable changes to be expected in industry before they were actually put into operation. For this reason, it would seem to me desirable for the Government to set up what I may call a ‘Prevision Committee’ of an advisory nature. The function of this committee would be to form an estimate of the trend of industry as a whole and the probable effects on our main industries of new ideas and inventions as they arose, and to advise whether any form of control was likely to prove necessary in the public interest.

“While all will agree that industry should be alert to take prompt advantage of new methods made possible by the advance of science, yet it may be important in the public interest to graduate the rate of change to prevent too serious dislocations in the social order. A committee of this kind would have a difficult and responsible task, but could not fail to be helpful to the Government in advising it of the trend of change for industry in general and to inform it of possible dislocations of industrial life which may suddenly arise from the impact of scientific discovery.”

Speaking of national organisation for research in India in an address prepared for delivery at the Jubilee Session of the Indian Science Conference, he stated not long before his death:—

“In Great Britain the responsibility for planning the programmes of research even when the cost is borne directly by the Government, rests with research councils or committees who are not themselves State servants but distinguished representatives of pure science and industry. It is to be hoped that if any comparable organisation is developed in India, there will be a proper representation of scientific men from the universities and corresponding institutions and also of the industries directly concerned. It is of the highest importance that the detailed planning of research should be left entirely in the hands of those who have the requisite specialized knowledge of the problems which require attack …”

Likewise Rutherford was not unmindful of the influence of the results and speculations regarding the history and structure of the earth and the universe. Very early in his career he showed that Kelvin's estimate of the age of the sun and the earth needed revision on account of the influence of radioactive energy, and he pointed out the method by which more reliable estimates could be obtained. His discussions with the aged Kelvin at the time bring out his innate courtesy and respect for the old.

In the foregoing, I have endeavoured to enumerate some of his achievements. I have not emphasised, as indeed he did not himself, all the honours bestowed on him. He was a Nobel Laureate. He received nearly 20 honorary degrees from universities of all countries. He was elected to the Order of Merit in 1925, and created Baron Rutherford of Nelson in 1931, and his heraldic arms bear witness to his New Zealand origin and subtly characterise some of his life work. When informed of this honour in 1931, he despatched the following characteristic cable to his mother in New Zealand: “Now Lord Rutherford. Honour more yours than mine.”

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He honoured his father and his mother in the far away Antipodes and every two weeks he found time to write in his own hand a letter to his aged mother describing domestic happenings, events, functions and journeyings in such a way as to give her delight. These letters are an eloquent acknowledgment of the debt he owed to her early influence and training.

His personal qualities are, I think, best summed up in the following description by Sir William Bragg several years before his death:—

“He possesses a keen love of research for its own sake. He has a fine judgment of the essential, and goes to work in a way which, when the end is reached, is seen to have been obviously direct. His arguments and results are expressed in simple straightforward language which reveals the completeness and force of his thoughts. He has the courage to break with precedent and to try out his own ideas. Rutherford has upset many theories, but he has never belittled anyone's work. He has added new pages to the book of Physical Science, and has always taught his students to venerate the old, even when the writing has become a little old-fashioned. Perhaps it is by characteristics such as these, quite as much as by his own scientific perception and technical skill, that Rutherford exercises such a wide influence. He takes always a broad and generous view, giving credit to others for their contributions to knowledge, and never pressing for the recognition of his own. For this reason, his students have worked under him with loyalty and affection, knowing that their interests were safe in his hands. For this reason, too, he has friends among the scientific workers of every country, and is welcome everywhere. Even these qualities would seem to be insufficient for the international reputation he holds. In addition, he has a sound grasp of the essentials of business and a quick understanding of the thoughts and feelings of those with whom he is dealing. It has happened at more than one gathering that progress has been slow until Rutherford has taken the lead, and, with his driving power and natural kindliness has brought about a successful issue. It is this unusual combination of so many qualities that has won for Rutherford a host of admirers.”

His old colleague, Professor Geiger, in an address in Berlin in November last wrote:—

“How gladly I recall those years which I spent as a young man in Manchester in his laboratory. A very wide circle of young investigators was gathered there from all countries. The work was intensive, but over all our toil was an atmosphere of light-heartedness and joy in our creative work. For Rutherford's inspiration, his keenness in work, and his unshakeable belief in success carried us all with him. With the utmost willingness he gave from the rich store of his knowledge; he gave help and encouragement in all the small and great troubles which arise in experimental work. He never thought of himself, always of the task in hand and of his young friends, whom he let share in praise and recognition far above their deserts. His textbook on Radioactivity is for the initiated a record of his selflessness. How often does the name of a disciple accompany a discovery which was yet completely his own creation.

“Rutherford believed in co-operation in research. Everyone in his laboratory knew what the others were working on, and Rutherford himself explained most willingly the progress of his own researches and of the problems which impelled him. If he had success in a new experiment, we were all called into his workroom. And in wonder we stood around his apparatus and listened to his animated words, and carried away with us the memory of a great hour.”

Such tributes from such men do not even do full justice to Rutherford's essential human characteristics as a man. It was his greatest charm that he could never be anything but himself. He knew his worth, but he always remained innately modest, simple and

– 16 –

without pose or pretence. He had extraordinary powers of concentration. He could work rapidly and for long hours, but at intervals he wisely shed all work and could enjoy a travel holiday to the full. He could flash fire on occasions, but neither as a youth nor in manhood did he ever sulk or bear malice. He took every opportunity of doing kindnesses to his friends and students and had a particularly warm spot for students from his home country who required help or guidance. In an age when science like industry is becoming less individualistic and when progress requires the organised efforts of many individuals, he displayed driving force and ability as an organiser, and through sheer inspiration of leadership encouraged the free development of initiative. There has never been a man in whom burning genius was so closely associated with kindly common sense, general sociability and the highest human qualities. Truly his was a life of service to his fellow men and to the ideal of truth.

E. M.

– 17 –

The Publications of the Late Lord Rutherford.

Compiled by C. M. Focken, Beverly-Mackenzie Lecturer in Physics, University of Otago.

The bibliography has been arranged chronologically, the date ascribed to the paper in question being the date of publication of the volume, number or part in which it appeared. Collaborators' names are given in brackets following the title of the paper. Titles of books are printed in italics. Standard contractions are used as far as possible for the journals cited. In citation the order of reference is series (Roman numeral), volume (Arabic numeral, heavy type), number or part (where necessary), page (Arabic numeral, normal type).

An endeavour was made to check each reference in detail, but this was not always possible, as some of the journals could not be consulted in New Zealand. It is hoped that any errors or omissions which inadvertently remain in the bibliography are few in number and of minor importance.

The author desires to acknowledge the valued assistance from many sources. He especially wishes to thank Mr. J. Harris (Librarian, University of Otago), Mr. E. R. Pitt (Chief Librarian, Public Library of Victoria), the librarians of the University Colleges at Auckland, Wellington and Christchurch, and the library staff at the University of Otago.

1894.

Nov. Magnetization of iron by high-frequency discharges. Trans. N.Z. Inst., 27:481–513.

1895.

Sept. Magnetic viscosity. Trans. N.Z. Inst., 28:182–204.

1896.

June A magnetic detector of electrical waves and some of its applications. Roy. Soc., Phil. Trans., 189:1–24.

" A magnetic detector of electrical waves and some of its applications. Abstract. Proc. Roy. Soc., 60:361:184–186.

Sept. A magnetic detector of electrical waves. Abstract. British Ass. for Adv. of Sc., Report, 724.

Nov. On the passage of electricity through gases exposed to Röntgen rays. [J. J. Thomson]. Phil. Mag., V:42:392–407.

1897.

April On the electrification of gases exposed to Röntgen rays, and the absorption of Röntgen radiation by gases and vapours. Phil. Mag., V:43:241–255.

Nov. The velocity and rate of recombination of the ions of gases exposed to Röntgen radiation. Phil. Mag., V:44:422–440.

1898.

June The discharge of electrification by ultra-violet light. Camb. Phil. Soc., Proc., 9:401–416.

1899.

Jan. Uranium radiation and the electrical conduction produced by it. Phil. Mag., V:47:109–163.

May Thorium and uranium radiation. [R. B. Owens]. Roy. Soc. of Canada, Trans., 2:5:9–12.

1900.

Jan. A radioactive substance emitted from thorium compounds. Phil. Mag., V:49:1–14.

Feb. Radioactivity produced in substances by the action of thorium compounds. Phil. Mag., V:49:161–192.

May Über eine von thoriumverbindungen emittierte radioaktive substanz. Phys. Zeit., 1:32:347–348.

June Energy of Röntgen and Becquerel rays and the energy required to produce an ion in gases. Abstract. [R. K. McClung]. Proc. Roy. Soc., 67:438:245–250.

Oct. Über die energic der Becquerel- und Röntgen-strahlen und über die zur erzeugung von ionen ingasen nötige energie. Phys. Zeit., 2:4:53–55.

– 18 –

1901.

Feb. Energy of Röntgen and Becquerel rays, and the energy required to produce an ion in gases. [R. K. McClung]. Roy. Soc., Phil. Trans., 196:25–59.

April Einfluss der temperatur auf die “emanationen” radioaktiver substanzen. Phys. Zeit., 2:29:429–431.

May The new gas from radium. [H. T. Brooks]. Roy. Soc. of Canada, Trans., 2:7:21–25.

" Discharge of electricity from glowing platinum. Roy. Soc. of Canada, Trans., 2:7:27–33.

June Emanations from radioactive substances. Nature, 64:157–158.

Aug. Dependence of the current through conducting gases on the direction of the electric field. Phil. Mag., VI:2:210–228.

Dec. Discharge of electricity from glowing platinum, and velocity of the ions. Phys. Rev., 13:321–344.

" Transmission of excited radioactivity. Abstract. Amer. Phys. Soc., Bull. 2:37–43.

1902.

Feb. Übertragung erregter radioaktivität. Phys. Zeit., 3:10:210–214.

March Erregte radioaktivität und in der atmosphäre hervorgerufene ionisation. [S. J. Allen]. Phys. Zeit., 3:11:225–230.

" Versuche über erregte radioaktivität. Phys. Zeit., 3:12:254–257.

April The new gas from radium. [H. T. Brooks]. Chem. News, 85:196–197.

" The radioactivity of thorium compounds. I. An investigation of the radioactive emanation. [F. Soddy]. Chem. Soc., Journ., 81:321–350.

May The existence of bodies smaller than atoms. Abstract. Roy. Soc. of Canada, Trans., 2:8:79–86.

June Magnetische ablenkbarkeit der strahlen von radioaktiven substanzen. [S. G. Grier]. Phys. Zeit., 3:17:385–390.

July Penetrating rays from radioactive substances. Nature, 66:318–319.

" Comparison of the radiations from radioactive substances. [H. T. Brooks]. Phil. May., VI:4:1–23.

" The radioactivity of thorium compounds. II. The cause and nature of radioactivity. [F. Soddy]. Chem. Soc. Journ., 81:837–860.

Aug. Sehr durchdringende strahlen von radioaktiven substanzen. Phys. Zeit. 3:22:517–520.

Sept. Deviable rays of radioactive substances. [A. G. Grier]. Phil. Mag., VI:4:315–330.

" The cause and nature of radioactivity. Part I. [F. Soddy]. Phil. Mag., VI:4:370–396.

Nov. The cause and nature of radioactivity. Part II. [F. Soddy]. Phil. Mag., VI:4:569–585.

Dec. Excited radioactivity and ionization of the atmosphere. [S. J. Allen]. Phil. Mag., VI:4:704–723.

" On the condensation points of the thorium and radium emanations. [F. Soddy]. Chem. Soc., Proc., 219.

1903.

Jan. Excited radioactivity and the method of its transmission. Phil. Mag., VI:5:95–117.

" Die magnetische und elektrische ablentung der leicht absorbierbaren radiumstrahlen. Phys. Zeit., 4:8:235–240.

Feb. The magnetic and electric deviation of the easily absorbed rays from radium. Phil. Mag., VI:5:177–187.

March Penetrating radiation from the earth's surface. Abstract. [H. L. Cooke]. Phys. Rev., 16:183.

April Radioactivity of ordinary materials. Nature, 67:511–512.

" The radioactivity of uranium. [F. Soddy]. Phil. Mag., VI:5:441–445.

" A comparative study of the radioactivity of radium and thorium. [F. Soddy]. Phil. Mag., VI:5:445–457.

" Some remarks on radioactivity. Phil. Mag., VI:5:481–485.

May Condensation of the radioactive emanations. [F. Soddy]. Phil. Mag., VI:5:561–576.

" Radioactive change. [F. Soddy]. Phil. Mag., VI:5:576–591.

– 19 –

Aug. The amount of emanation and helium from radium. Nature, 68:366–367.

Oct. Heating effect of the radium emanation. [H. T. Barnes]. Nature, 68:622.

Dec. Heating effect of the radium emanation. [H. T. Barnes]. Nature, 69:126.

" Radioactive processes. Phys. Soc., Proc., 18:595–597, 598–600.

1904.

Jan Radioactivity of radium and its concentration. Nature, 69:222.

Feb. Heating effect of the radium emanation. [H. T. Barnes]. Phil. Mag., VI:7:202–219.

March Nature of the gamma rays from radium. Nature, 69:436–437.

June The succession of changes in radioactive bodies. Abstract. Proc. Roy. Soc., 73:495:493–496.

Nov. Slow transformation products of radium. Phil. Mag., VI:8:636–650.

" Succession of changes in radioactive bodies. Roy. Soc., Phil. Trans., 204:169–219.

Dec. Heating effect of the gamma rays of radium. [H. T. Barnes]. Nature, 71:151–152.

Difference between radioactivity and chemical change. Jahrbuch d. Radioaktivität u. Elektronik, 1:103–127.

Radioactivity. [Camb. Univ. Press].

1905.

Jan. Present problems of radioactivity. Archives des Sciences, 19:31–59.

Feb. Slow transformation products of radium. Nature, 71:341–342.

March Charge carried by the alpha rays from radium. Nature, 71:413–414.

" Positive charge of alpha rays. Elect. Rev., N.Y., 46:490.

May Heating effect of the gamma rays from radium. [H. T. Barnes]. Phil. Mag., VI:9:621–628.

" Note on the radioactivity of weak radium solutions. Phil. Mag., VI:9:711–712.

" Anmerkung [zu der arbeit von A. S. Eve: Die eingenschaften geringer radiummenger]. Phys. Zeit., 6:9:269.

July Relative proportion of radium and uranium in radioactive minerals. [B. B. Boltwood]. Amer. Journ. Sci., 20:55–56.

" Proportion of radium and uranium in minerals. [B. B. Boltwood]. Chem. News., 92:38–39.

" Some properties of the alpha rays from radium. Phil. Mag., VI:10:163–176.

Aug. Charge carried by the alpha and beta rays of radium. Phil. Mag., VI:10:193–208.

Sept. Slow transformation products of radium. Phil. Mag., VI:10:290–306.

1906.

Jan. Some properties of the alpha rays from radium. (Second Paper). Phil. Mag., VI:11:166–176.

Feb. Magnetic and electric deflection of the alpha rays of radium. Abstract. Phys. Rev., 22:122–123.

March Über einige eigenschaften der alpha-strahlen des radiums. Phys. Zeit., 7:5:137–143.

April The retardation of the velocity of the alpha particles in passing through matter. Phil. Mag., VI:11:553–554.

July Relative proportion of radium and uranium in radioactive minerals. [B. B. Boltwood]. Amer. Journ. Sci., 22:1–3.

Aug. Retardation of the alpha particle from radium in passing through matter. Phil. Mag., VI:12:134–146.

" Distribution of the intensity of the radiation from radioactive sources. Phil. Mag., VI:12:152–158.

Oct. Absorption of radioactive emanations by charcoal. Nature, 74:634.

" The recent radium controversy. Nature, 74:634–635.

" The mass and velocity of the alpha particles expelled from radium and actinium. Phil. Mag., VI:12:348–371.

" Mass of the alpha particles from thorium. [O. Hahn]. Phil. Mag., VI:12:371–378.

Radioactive transformations. [Yale Univ. Press; Constable & Co.]

– 20 –

1907.

Jan. Production of radium from actinium. Nature, 75:270–271.

" The velocity and energy of the alpha particles from radioactive substances. Phil. Mag., VI:13:110–117.

June The origin of radium. Nature, 76:126.

Aug. The production and origin of radium. Abstract. British Ass. for Adv. of Sci., Report, 456.

" The effect of high temperature on the activity of the products of radium. Abstract. [J. E. Petavel]. British Ass. for Adv. of Sci., Report, 456–457.

Oct. Origin of radium. Nature, 76:661.

" The production and origin of radium. Manchester Lit. and Phil. Soc., Mem., IV:52:5–7.

Dec. The production and origin of radium. Phil. Mag., VI:14:733–749.

1908.

Feb. A method of counting the number of alpha particles from radioactive matter. [H. Geiger]. Manchester Lit. and Phil. Soc., Mem., IV:52:9:1–3.

March Recent advances in radioactivity. Nature, 77:422–426.

July Spectrum of the radium emanation. [T. Royds]. Nature, 78:220–221.

Aug. Experiments with the radium emanation. (1) The volume of the emanation. Phil. Mag., VI:16:300–312.

" Spectrum of the radium emanation. [T. Royds]. Phil. Mag., VI:16:313–317.

" An electrical method of counting the number of alpha particles from radioactive substances. [H. Geiger]. Proc. Roy. Soc., A, 81:546:141–161.

" The charge and nature of the alpha particle. [H. Geiger]. Proc. Roy. Soc., A, 81:546:162–173.

Nov. The nature of the alpha particles. Nature. 79:12–15.

" The action of the radium emanation upon water. [T. Royds]. Phil. Mag., VI:16:812–818.

" Nature of the alpha particle. [T. Royds]. Manchester Lit. and Phil. Soc., Mem., IV:53:1:1–3.

" Some properties of the radium emanation. Manchester Lit. and Phil. Soc., Mem., IV:53:2:1–2.

1909.

Jan. Nature of the alpha particle. [T. Royds]. Chem. News, 99:49.

" Eine elektrische methode, die von radioaktiven substauzen ausgesandten alpha-teilchen zu zählen. [H. Geiger]. Phys. Zeit., 10:1:1–6.

" Die ladung und natur des alpha-teilchens. [H. Geiger]. Phys. Zeit., 10:2:42–46.

Feb. The boiling-point of the radium emanation. Nature, 79:457–458.

" The nature of the alpha particle from radioactive substances. [T. Royds]. Phil. Mag., VI:17:281–286.

April Recent advances in radioactivity. Chem. News, 99:171–174, 181–183.

" Differences in the decay of the radium emanation. [Y. Tuomikoski]. Manchester Lit. and Phil. Soc., Mem., IV:53:12:1–2.

May Condensation of the radium emanation. Phil. Mag., VI:17:723–729.

Aug. Atomic theory and the determination of atomic magnitudes. British Ass. for Adv. of Sci., Report, 373–385.

Nov. The action of the alpha rays on glass. Manchester Lit. and Phil. Soc., Mem., IV:54:5:1.

" Production of helium by radium. [B. B. Boltwood]. Manchester Lit. and Phil. Soc., Mem., IV:54:6:1–2.

1910.

Jan. Action of the alpha rays on glass. Phil. Mag., VI:19:192–194.

Feb. Properties of polonium. Nature, 82:491–492.

May Theory of the luminosity produced in certain substances by alpha rays. Proc. Roy. Soc., A., 83:566:561–572.

– 21 –

Oct. Radium standards and nomenclature. Nature, 84:430–431.

" The number of alpha particles emitted by uranium and thorium and by uranium minerals. [H. Geiger]. Phil. Mag., VI:20:691–698.

" The probability variations in the distribution of alpha particles. [H. Geiger]. Phil. Mag., VI:20:698–704.

1911.

March The scattering of the alpha and beta rays and the structure of the atom. Manchester Lit. and Phil. Soc., Mem., IV:55:18–20.

" Untersuchungen über die radiumemanation. II. Die umwandlungs-geschwindigkeit. K. Akad. Wiss., Vienna, Sitzungsberichte, 120:2a:303–312.

" Die erzeugung von helium durch radium. [B. B. Boltwood]. K. Akad. Wiss., Vienna, Sitzungsberichte, 120:2a:313–336.

April Radioactivity of thorium. Röntgen Soc., Journ., 7:23–30.

May The scattering of alpha and beta particles by matter and the structure of the atom. Phil. Mag., VI:21:669–688.

Oct. Production of helium from radium. [B. B. Boltwood]. Phil. Mag., VI:22:586–604.

" Transformation and nomenclature of the radioactive emanations. [H. Geiger]. Phil. Mag., VI:22:621–629.

An international standard of radium. Akad. Verlagsgesellschaft, Leipzig.

1912.

April Balance method for comparison of quantities of radium. [J. Chadwick]. Phys. Soc., Proc., 24:141–151, 156–157.

May Balance method for comparison of quantities of radium. [J. Chadwick]. Le Radium, 9:195–200.

Oct. The origin of beta and gamma rays from radioactive substances. Phil. Mag., VI:24:453–462.

" Photographic registration of alpha particles. [H. Geiger]. Phil. Mag., VI:24:618–623.

" Origin of beta and gamma rays from radioactive substances. Le Radium, 9:337–341.

" Wärme-entwicklung durch radium und radiumemanation. [H. Robinson]. K. Akad. Wiss., Vienna, Sitzungsberichte, 121:2a:1491–1516.

Dec. On the energy of the groups of beta rays from radium. Phil. Mag., VI:24:893–894.

1913.

Jan. A new International Physical Institute. Nature, 90:545–546.

Feb. Heating effect of radium and its emanation. [H. Robinson]. Phil. Mag., VI:25:312–330.

April The age of pleochroic haloes. [J. Joly]. Phil. Mag., VI:25:644–657.

May The analysis of the gamma rays from radium B and radium C. [H. Richardson]. Phil. Mag., VI:25:722–734.

Aug. Analysis of the gamma rays from radium D and radium E. [H. Richardson]. Phil. Mag., VI:26:324–332.

Oct. The reflection of gamma rays from crystals. [E. N. da C. Andrade]. Nature, 92:267.

" Scattering of alpha particles by gases. [J. M. Nuttall]. Phil. Mag., VI:26:702–712.

" The analysis of the beta rays from radium B and radium C. [H. Robinson]. Phil. Mag., VI:26:717–729.

Nov. Über die masse und die geschwindigkeiten der von den radioaktiven substanzen ausgesendeten alpha teilchen. [H. Robinson]. K. Akad. Wiss., Vienna, Sitzungsberichte, 122:2a:1855–1884.

Dec. The British radium standard. Nature, 92:402–403.

" Structure of the atom. Nature, 92:423.

" Analysis of the gamma rays of the thorium and actinium products. [H. Richardson]. Phil. Mag., VI:26:937–948.

Radioactive substances and their radiations. [Camb. Univ. Press].

– 22 –

March The structure of the atom. Phil. Mag., VI:27:488–498.

May The wavelength of the soft gamma rays from radium B. [E. N. da C. Andrade]. Phil. Mag., VI:27:854–868.

Aug. The spectrum of the penetrating gamma rays from radium B and radium C. [E. N. da C. Andrade]. Phil. Mag., VI:28:263–273.

" Spectrum of the beta rays excited by gamma rays. [H. Robinson and W. F. Rawlinson]. Phil. Mag., VI:28:281–286.

" Discussion on the structure of atoms and molecules. Abstract. British Ass. for Adv. of Sci., Report, 293–294 and 301.

Sept. The connexion between the beta and gamma ray spectrum. Phil. Mag., VI:28:305–319.

" Radium constants on the International Standard. Phil. Mag., VI:28:320–327.

Oct. The mass and velocities of the alpha particles from radioactive substances. [H. Robinson]. Phil. Mag., VI:28:552–572.

1915.

March Origin of the spectra given by beta and gamma rays of radium. Manchester Lit and Phil. Soc., Mem., IV:59:17–19.

July Radiations from exploding atoms. Nature, 95:494–498.

Sept. Maximum frequency of the X-rays from a Coolidge tube for different voltages. [J. Barnes and H. Richardson]. Phil. Mag., VI:30:339–360.

" Efficiency of the production of X-rays from a Coolidge tube. [J. Barnes]. Phil. Mag., VI:30:361–367.

1916.

April Long-range alpha particles from thorium. [A. B. Wood]. Phil. Mag., VI:31:379–386.

Oct. X-ray spectra of the elements. Engineering, 102:320.

1917.

Sept. Penetrating power of the X-radiation from a Coolidge tube. Phil. Mag., VI:34:153–162.

1918.

July X-rays. Röntgen Soc., Journ., 14:75–86.

1919.

June Collision of alpha particles with light atoms. I. Hydrogen. Phil. Mag., VI:37:537–561.

" Collision of alpha particles with light atoms. II. Velocity of the hydrogen atoms. Phil. Mag., VI:37:562–571.

" Collision of alpha particles with light atoms. III. Nitrogen and oxygen atoms. Phil. Mag., VI:37:571–580.

" Collision of alpha particles with light atoms. IV. An anomalous effect in nitrogen. Phil. Mag., VI:37:581–587.

Nov. Radium and the electron. Nature, 104:226–230.

Dec. Radioactivity and gravitation. [A. H. Compton]. Nature, 104:412.

1920.

July Nuclear constitution of atoms. Proc. Roy. Soc., A, 97:686:374–400.

Sept. Building-up of atoms. Engineering, 110:382.

1921.

Feb. On the collision of alpha particles with hydrogen atoms. Phil. Mag., VI:41:307–308.

March The disintegration of elements by alpha particles. [J. Chadwick]. Nature, 107:41.

March and April. Electricity and matter. Engineering, 111:296–297, 345–347, 379–381.

April The mass of the long-range particles from thorium C. Phil. Mag., VI:41:570–574.

Nov. The artificial disintegration of light elements. [J. Chadwick]. Phil. Mag., VI:42:809–825.

Radium and the Electron. [Smithsonian Institution, Annual Report, 1919].

– 23 –

1922.

Feb. Artificial disintegration of the elements. Chem. Soc., Journ., 121:400–415.

March and April. Radioactivity. Engineering, 113:299–300, 331–332, 365–366, 386–387, 414–415, 464–466.

April Disintegration of elements. Nature, 109:418.

" Radioactivity. Electrician, 88:411–413, 501–504.

May Artificial disintegration of the elements. Nature, 109:584–586, 614–617.

June Identification of a missing element. Nature, 109:781.

" Electricity and matter. Inst. Elec. Eng., Journ., 60:613–618.

Aug. Electricity and matter. Nature, 110:182–185.

Sept. The disintegration of elements by alpha particles. [J. Chadwick]. Phil. Mag., VI:44:417–432.

1923.

March and June. Atomic projectiles and their properties. Engineering, 115:242–243, 264–266, 306–308, 338–340, 358–359, 798–800.

April, July, and Aug. Atomic projectiles and their properties. Electrician, 90:366–367, 91:60–61, 120–121, 144–145.

June Life-history of an alpha particle. Engineering, 115:769–770.

" Capture and loss of electrons by alpha particles. Camb. Phil. Soc., Proc., 21:504–510.

Aug. Life-history of an alpha particle. Nature, 112:305–312.

" The life of an alpha particle. Electrician, 91:194–195.

" The electrical structure of matter. British Ass. for Adv. of Scie., Report, 1:24.

Sept. The electrical structure of matter. Nature, 112:409–419.

1924.

Feb. The capture and loss of electrons by alpha particles. Phil. Mag., VI:47:277–303.

March The bombardment of elements by alpha particles. [J. Chadwick]. Nature, 113:457.

March and April. Properties of gases in high and low vacua. Engineering, 117:330, 365–366, 387, 429.

April The nucleus of the atom. Engineering, 117:458–459.

Aug. Further experiments on the artificial disintegration of elements. [J. Chadwick]. Phys. Soc., Proc., 36:417–422.

Sept. On the origin and nature of the long-range particles observed with sources of radium C. [J. Chadwick]. Phil. Mag., VI:48:509–526.

" Early days of radioactivity. Frank. Inst., Journ., 198:281–290.

Dec. Natural and artificial disintegration of the elements. Frank. Inst., Journ., 198:725–744.

1925.

March The stability of atoms. Disc., 6:402–403.

" The stability of atoms. Roy. Soc. Arts, Journ., 73:389–402.

April Disintegration of atomic nuclei. Nature, 115:493–494.

" Studies of atomic nuclei. Engineering, 119:437–438.

Aug. Moseley's work on X-rays. Nature, 116:316–317.

Nov. Scattering of alpha particles by atomic nuclei and the law of force. [J. Chadwick]. Phil. Mag., VI:50:889–913.

" The natural X-ray spectrum of radium B. [W. A. Wooster]. Camb. Phil. Soc., Proc., 22:834–837.

Electrical Structure of Matter. [Smithsonian Institution, Annual Report, 1924].

1926.

March and April. The rare gases of the atmosphere. Engineering, 121:353–354, 388–390, 438, 458–459.

May Discussion on the electrical state of the upper atmosphere. Proc. Roy. Soc., A, 111:757:1–3.

Dec. Electric waves and their propagation. Nature, 118:809–811.

1927.

Jan. Anniversary address by the President of the Royal Society, November, 1926. Proc. Roy. Soc., A, 113:765:481–495.

April Alpha rays and atomic structure. Engineering, 123:375–376, 409–410, 460–461, 492–493.

– 24 –

June Atomic nuclei and their transformations. Phys. Soc., Proc., 39:359–372.

Sept. Structure of the radioactive atom and origin of the alpha rays. Phil. Mag., VII:4:580–605.

" The scattering of alpha particles by helium. [J. Chadwick]. Phil. Mag., VII:4:605–620.

Nov. Study and research in Physics. Nature, 120:657–659.

Dec. Scientific aspects of intense magnetic fields and high voltages. Nature, 120:809–811.

1928.

Jan. Anniversary address by the President of the Royal Society, November, 1927. Proc. Roy. Soc., A, 117:777:300–316.

" Professor Bertram B. Boltwood. Nature, 121:64–65.

March Transformation of matter. Engineering, 125:315–316, 360, 387.

Dec. Production and properties of high-frequency radiation. Nature, 122:883–886.

1929.

Jan. Anniversary address by the President of the Royal Society, November, 1928. Proc. Roy. Soc., A, 122:789:1–23.

March Origin of actinium and age of the earth. Nature, 123:313–314.

March and April. Molecular motions in rarefied gases. Engineering, 127:319–321, 347–348, 381, 449–450.

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