The New Zealand Railways Magazine, Volume 12, Issue 11 (February 1, 1938)
The Lord Rutherford of Nelson
In the last issue of the “New Zealand Railways Magazine,” I endeavoured to give an account of Rutherford's earlier life in New Zealand, including the time immediately prior to his leaving for England, when he was engaged at Canterbury College on experimentation with a magnetic detector for radio waves.
In the following article, at the risk of being somewhat technical, I would like to summarise some of his achievements. I wish to bring home to his fellow countrymen two things—firstly, that he was a true son of New Zealand, nurtured here and of her pioneer stock, and secondly, that he was a world-famous man for, alas, too often a prophet is not without honour save in his own country.
On his arrival at Cambridge, he spent the first few months in endeavours to increase the sensitiveness of his radio detector, but he had not worked there more than a few weeks before he had convinced the head of the Cavendish Laboratory, Sir J. J. Thomson, that he was a student of quite exceptional ability and energy. This trait of Rutherford's, it is interesting to relate, gave rise to the story that there was a “young rabbit from New Zealand who burrows very deep.” At that time Rutherford held the record for long distance wireless in England, having detected at the laboratory signals which came from the observatory two miles away. However, a remarkable combination of circumstances caused him to change his line of work. Sir J. J. Thomson and his fellow workers had for ten years been engaged on the problems associated with the passage of electricity through gases which they had found to occur in a partially evacuated chamber. The modern Neon light shop signs are an example of this. 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 less than 1/1800 part by weight of the elementary atoms or ultimate particles of the gases concerned. In 1895, just as Rutherford had gone up to Cambridge, Rontgen 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. These rays had the power of passing through the glass walls of the chamber, and also through outside opaque objects and affected, too, a photographic plate. These rays, called Rontgen rays, or X rays, were found to have other interesting properties in that they made the outside air electrically conducting or “ionised.” Rutherford's attention was being attracted to this astonishing phenomenon and he commenced work on it. Sir J. J. Thomson describes this 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 only been descriptive.”
During 1896, while Rutherford was gaining the inspiration and enthusiasm of a pioneer in this subject, Becquerel, in France, made a further remarkable and allied discovery, namely, that salts of the metal uranium gave out radiations which, like Rontgen rays, could penetrate opaque bodies and affect a photographic plate. This was the start of the subject of “radio-activity,” and Rutherford immediately applied the knowledge and technique of his work on ionisation produced by X rays to the investigation of the radiations from uranium and from other radio-active bodies subsequently discovered. These latter included radium discovered by Pierre and MMe. Curie, thorium, actinium, and a host of other substances produced, as Rutherford showed later, by the natural disintegration of these parent elements.
By 1898, Rutherford had made a careful study of the radiations from radio active bodies. He found that there were three types of radiation which he called alpha, beta and gamma rays, names which still persist. The alpha rays or alpha particles he showed to be atoms of the second lightest known element, helium, expelled with speeds of the order of 12,000 miles per second. The beta rays or beta particles he showed to be particles of negative electricity, i.e., electrons, ejected from the parent atom with colossal speeds of up to 180,000 miles per second. The gamma rays were found to be electro-magnetic vibrations similar to light and to the wireless waves of Rutherford's early experiments, only of a very much higher frequency, higher even than that of X rays (100,000,000,000,000 megacycles per second, a figure which will be appreciated by radio enthusiasts). In subsequent work, a study of each of these types of radiation led him to the unfolding of many of Nature's secrets over wide fields, to give us a vivid, realistic and wonderful picture of the structure of atoms, i.e., the fundamental chemical units out of which all kinds of matter are built up. Well we may pause here to wonder that one man in a single lifetime can have accomplished so much.
Rutherford's work during the three years 1895–98 at Cambridge attracted world-wide attention and it is not surprising that, although so young, he was offered a research professorship at McGill University, Montreal. Rutherford accepted this post mainly on account of the laboratory facilities available, through the munificence of Sir page 10 page 11 William Macdonald. Rutherford had considered the possibility of an application for a professorship at the proposed Victoria College, Wellington, but, as in many other decisions in connection with professorships which were offered to him later, literally in dozens, from America and other countries, the main considerations with him were facilities and equipment to pursue his researches. These, to his mind, far outweighed all questions of salary.
At McGill, although at first without the association of those with direct knowledge of his subject, he quickly settled down to work and attracted to himself many co-workers, for he was far from being a recluse. He “radiated” enthusiasm, interest, and will to co-operate.
For four years, he worked night and day from experiment to experiment, investigating the nature of the radiations from radio-active bodies and the manner in which the substances disintegrated. He discovered, for instance that thorium, the substance from which gas mantles are made, gave off a gas which he called thorium emanation, which was itself radio-active, but whose activity decayed with time according to a definite law falling to half value in about one minute. Contemporaneously, he noticed that substances exposed to this emanation had deposited upon them a new substance which was itself radio-active, decaying to a half value in about eleven hours. The concentration of this new active substance could be increased by deposition on a negatively charged electrode; also he found that it was soluble in certain solutions and could be dissipated or volatilized by heat. With radium he found there was produced an emanation of a half-period of 3.8 days; this emanation (radon) decayed according to a similar law as the thorium emanation, but gave rise to an active deposit which decayed to half value in a few minutes.
At this stage Professor Soddy joined forces with him and together they investigated the chemical properties of these various radio-active substances and ultimately, in 1902, after a review of all the known experimental facts they put forth the bold and startling theory known as the Disintegration Theory. According to this theory atoms were no longer regarded as permanent, everlasting, and indivisible. Radio-active elements disintegrated spontaneously. They broke up according to the laws of chance independently of age or their physical or chemical state or surroundings. The average mortality rate was constant for any one radio-active 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 alpha particle or a beta particle.
In many cases, the ejection of a beta particle was accomplished by the liberation of further energy in the form of a gamma ray.
At this stage, we may pause to review briefly the history of the conception of the atom. Democritus first put forward the idea of atoms. These he considered as the final stage in the process of breaking down a piece of any substance into smaller and smaller pieces. The atom of Democritus was more in the nature of a general concept than a definite atomic model, and could not be supposed to possess any intrinsic properties.
At Manchester, he gathered around him a large team of workers, representative of over a dozen nationalities. Apart from details of discovery too numerous to mention, he made during this period three epoch-making advances. Firstly, he developed a method of counting helium atoms, one by one, to obtain an accurate estimation of the fundamental constants of the atoms and of electricity; secondly, he put forward, in 1911, as a result of experiment, a theory and picture of the constitution of the atom, beautiful in its simplicity. He pictured the atom as a universe in ultra-miniature; a replica page 12 of the solar system with the same order or scale of relative dimensions of its parts. The nucleus or central sun had an aggregate of positive electricity, the corresponding number of units of negative electricity or electrons occupied orderly closed orbits round the nucleus similar 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—one for hydrogen; two for helium; three for lithuum and so on up to 92 for uranium. The method by which this was worked out was to shoot alpha particles (analogous to comets entering the solar system) into the region of the central nucleus and from, the deflections or orbits observed, to calculate the nature of the forces encountered within the atom, thus arriving at the nature of the electric charge and at the mass of the atomic nucleus. This led one of his students, Bohr from Denmark, to work out mathematically the type of the spectrum of light which the atom was able to emit under suitable circumstances and thus solve the problem of the origin of what is known as “spectra.”
This same method of experiment led to the third great discovery of this period which was, in effect, the accomplishment of the dream of the alchemists of old, the transmutation of matter. Under certain circumstances of a direct hit on the nucleus of the atom against which this atomic artillery of alpha particles was directed, the atoms could be made to disintegrate artificially with the production of new types of atoms. Thus, for example, it was found that under certain circumstances when firing alpha particles into nitrogen gas, an original nitrogen atom was transformed into an oxygen atom together with a hydrogen nucleus. The author of this article may perhaps be forgiven in mentioning that he was instrumental in making the initial experiments leading to both the discoveries just mentioned. Rutherford's genius was required, however, for their full meaning and interpretation.
The Great War intervened to interrupt this work and the laboratory was deserted. Rutherford himself was summoned to the national war councils in connection with scientific matters, mainly concerned with submarine detection. He also visited the United States to find out what they were doing in this matter and to tell them what we were doing in Britain.
After the War, in 1919, he was called to the Professorship and head of the famous Cavendish Laboratory at Cambridge, vacated by his old chief, Sir J. J. Thomson, and he began to pursue with characteristic energy the paths marked out by his great discoveries at Manchester. The experiments bearing on atomic structure were his main interest, and he and his co-workers elaborated the methods and results of disintegration and transformation of atoms by means under human control. The year 1932 saw the discovering in his laboratory of a new particle, the neutron, the properties of which had been anticipated by Rutherford for many years.
His life, all too short, was neither incomplete in its entity or attainment, 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 importance is, I think, one of the greatest tragedies in the history of Science.”
For the last seven years of his life, he was Chairman of the British Council of Scientific and Industrial Research. It was an article of faith with him that the future of Great Britain depended on the effective use of Science by Industry. “It was this faith,” states Sir Frank Smith, “which induced him, a man of the highest attainment in the field of pure research, to devote himself as he did unreservedly, to the work. The development of the industrial research association movement, now taking place, owes much to his foresight, sympathy and advocacy.”
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 almost countless honours from all countries. He was created Lord Rutherford of Nelson and his heraldic arms bear witness to his New Zealand origin and subtly characterise some of his life work. When informed of his Honour in 1931, he despatched the following characteristic cable to his mother in New Zealand: “Now Lord Rutherford. Honour more yours than mine.” 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 the domestic happenings, descriptions of events, functions and journeyings, in such a way as to give her delight.
I cannot adequately express his personal qualities. He knew his worth, but he always remained inately modest, simple and without pose or pretense. He was loved, with deep affection, by his fellow workers and students and he took constant care of them. He was a shrewd judge of character, forceful in statement and action, clear and honest of purpose, noble and generous. 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 service to his fellow men and to the ideals of truth.page 13
Mr. G. H. Mackley, C.M.G.,
General Manager, New Zealand Railways.
In an editorial reference to the New Year Honours, the “Southland Times” makes the following comment on the honour of C.M.G. conferred upon Mr. G. H. Mackley: “Mr. G. H. Mackley stands at the head of those civil servants who have received recognition: but the nature of his task as General Manager of the New Zealand Railways places him in a special category. It is generally known that Mr. Mackley has entered into his work with unusual energy, and an insight into the problems of an essential service which is also the largest single business undertaking in the country. His new honour is a fitting recognition of his work in an exacting task, and of personal qualities which have won universal respect.”