G. Johnstone Stoney
(15 Feb 1826 - 5 Jul 1911)
GEORGE JOHNSTONE STONEY, 1826 - 1911
Obituary Notice from Proceedings of The Royal Society (1912)
THE family from which George Johnstone Stoney was derived, on his father's side, settled in Ireland in the seventeenth century, coming from Yorkshire. From the marriage of George Stoney of Oakley Park, King's County, with Anne, daughter of Bindon Blood, D.L., of Cranagher and Rockforest, County Clare, was born in February, 1826, George Johnstone Stoney, eldest son and third child. One other son also was born, Bindon Blood Stoney. The latter, a distinguished engineer, and a Fellow of the Royal Society, died early in 1900. A sister of the late George Johnstone Stoney married her cousin the Rev. William FitzGerald, Bishop of Killaloe, a union which gave rise to the late George Francis FitzGerald, whose remarkable genius, especially in physical science, is known to all. Other distinguished relatives are to be found in William Bindon Blood (mother's brother), who was a professor of engineering and author of professional papers; in General Sir Bindon Blood, G.C.B. (son of mother's brother), Commander of the Forces in the Punjab and distinguished in the Chitral Expedition and in the Boer War; and in Maurice FitzGerald, lately Professor of Civil Engineering, in Queen's University, Belfast.
The Stoneys' country property in Ireland was of considerable value during the early years of the last century. Those were times of large profits to agricultural undertakings, the Napoleon Wars conferring an artificial value on home produce. Irish property fell in value when the wars ceased, and country gentlemen found that encumbrances incurred during the more prosperous times, and as the result of lavish hospitality, were not so easily met as in the good times. Poverty fell upon them and the terrible times of the Irish Famine (1846-48), intensified by the monstrous policy of that day which decreed the local raising of the Poor Law rate just where the famine was most severe, completed the ruin of many Irish families in those districts where the unfortunate tenants stood most in need of the landlord's assistance. The Stoneys' property had to be sold; it fetched about eight years' purchase of the reduced rental, and Johnstone Stoney's widowed mother and her children had no other means.
Many county families who had similarly lost their landed property flocked to Dublin and turned to professional careers in order to make their way in the world. It was a strenuous time in this younger society of Dublin, and one of much mutual helpfulness. Johnstone Stoney and his brother Bindon entered Trinity College, earning the expense of their fees by "grinding" or in English phraseology "coaching." Although unable to afford such assistance for themselves, both brothers had distinguished college careers, Johnstone never failing to obtain a place amongst the first three in the First Class honour lists, and taking a Second Senior Moderatorship in Mathematics and Physics in the Final, the first place going to the distinguished mathematician Mr. Morgan Crofton, F.R.S. In those days scholarships all went to classical men.
When Johnstone Stoney left college Lord Rosse made him his first regular astronomical assistant at Parsonstown, a post subsequently filled by Robert Ball and by other young men who later on made a distinguished mark in science. Stoney read for the Trinity College Fellowship while at Parsonstown. He entered for it in 1852 and took second place, winning thereby the Madden Prize, which is worth about £300. It was the last examination conducted in Latin, and a wide range of subjects was included in the course, the cumulative marks deciding. Although not so severe an examination as it has since become, the ordeal was a severe one. Stoney was examined in Hebrew, chronology, metaphysics, and classics, besides his own special subjects of mathematics and physics. The range of subjects, the method of cumulative marking, and the encumbrance of Latin as a medium of expression, would handicap any science student. It was, too, an examination in which brilliant originality of mind counted practically for nothing.
Stoney is one of many distinguished men whom Trinity College has lost as the result of the exclusively examinational mode of entry to Fellowships. Johnstone Stoney could not afford to try for the Fellowship again, and Lord Rosse, who was always a true friend to him, used his influence to have him appointed to the Chair of Natural Philosophy in Queen's College, Galway. Stoney remained five years in Galway and then became Secretary to the Queen's University, which brought him back to Dublin and to the wider life of a great University city, a change keenly appreciated by him.
For many years after this Stoney devoted himself enthusiastically to the work of solving the problem of the provincial university, in other words to securing to the local university the same beneficent influence which the greater central universities exert upon those more wealthy students who can afford the cost of residence away from home. The problem was then a new one, for although the older universities have in past centuries gone through times of mere provincial importance, the conditions of their growth and development were different from those which affect a recent institution The latter has to face at once the rivalry of the older institutions, with their greater prestige, and the facilities of modern modes of travel. In Ireland the whole question is complicated by differences in views as to the mental standpoint of the university, differences founded upon religious principles which seem impervious to argument.
In the midst of these labours, which continued till 1882, when the Queen's University was dissolved, other chances came to Johnstone Stoney, but his devotion to what he hoped would have been his life's work prevented his considering them, though some of these offers would have benefited him pecuniarily and others would have given him greater leisure for research, the latter a condition far outweighing the former in his estimation.
The office of the Queen's University was then situated in Dublin Castle, and Stoney's conversance with educational matters led to his being frequently consulted by both political parties. He was frequently brought over to the House of Commons, so as to be at hand to give information to the Chief Secretary of the day when Irish educational matters were in question. He wrote many reports on educational subjects, more especially for Sir Thomas Larcom. When Sir Thomas retired, he was anxious that Stoney should succeed him as Permanent Secretary in Ireland. Lord Mayo, then Lord-Lieutenant, sounded him on the subject; however, Stoney frankly told him he approved of Mr. Gladstone's Irish Church Disestablishment Bill as the healthiest policy for the Church itself. This closed the matter, as Lord Mayo was a Conservative and opposed to Mr. Gladstone's policy.
At the request of the Civil Service Commissioners, Stoney added to his other duties those of Superintendent of the Civil Service examinations in Ireland. The double duties added much to his already heavy office work, and sorely curtailed what leisure he had for scientific work. In 1882 the dissolution of the Queen's University fell as a crushing blow upon Stoney.
" At a stroke of the pen, I beheld the labour of nearly thirty years of my life annulled"—in such words he described the event to the present writer.
There is no doubt that the policy of dissolution was a most questionable one. The University was dissolved just when becoming most successful. In its stead an examining University was installed, and the several colleges of the old Queen's University became feeders to this institution, which had the power of conferring degrees on purely examinational tests, degrees bearing the same status as those conferred upon students who were not in residence in the colleges. The evils arising, and developing with the lapse of years, in the new Royal University found little defence when, many years later, the latter became the subject of enquiry by the Irish University Commission of 1901. The Commissioners reported that, in addition to defects of organisation, the Royal University " has seriously impaired the value of the University education which was previously in existence. On this side its influence has been one of positive destruction; since it came into being, the growth of the Queen's Colleges has been arrested." In the end, the Royal University, which had supplanted the Queen's, was in turn swept away, and, the present National University of Ireland and the Queen's University of Belfast installed in its place, the purely examinational system being, it is to be hoped, banished for good.
It was during this long period of residence in Dublin that Stoney's influence made itself felt in the policy of the Royal Dublin Society. This Society is unique among voluntary institutions in the United Kingdom—unique in organisation, and, it may be said, unique in the influence it has exerted upon almost every factor tending towards advance of civilisation and national prosperity. Originating in the efforts of a few enthusiasts to better the arts and industries of Ireland, it was founded in 1731, having its first home in Trinity College. Developing year by year, it fostered not only industries but science, and to its inception are due the Royal Botanic Gardens of Dublin, the Royal College of Science, the National Library. the National Museums of Art, Archaeology, and Natural Science, and the National Art Gallery of Ireland.
In this Society Stoney served as Honorary Secretary for over twenty years, and afterwards as Vice-President, until he left Dublin for London, on his retirement from official life, in 1893. During his tenure of office the Society went through great and fundamental changes, exacting much extra work from its officers. The Society used to be the channel through which the Government administered grants in Ireland to Agriculture, Science, and Art. The time came when the Treasury felt that it was anomalous for public grants to be administered by a private, voluntary society and out of the direct control of a Public Department. The Royal Dublin Society, in Stoney's time of office as Honorary Secretary, handed over its great collections to the Government, receiving an allotment of capital for the pursuance of its scientific functions, and for enlarging and amplifying its agricultural shows and otherwise helping Irish agriculture. The premises at Ball's Bridge were acquired at this time, and an era of advance in the magnitude and influence of its shows initiated, which has resulted in making them of international importance.
Towards the close of his personal influence in the Royal Dublin Society, Stoney induced the Council to inaugurate concerts directed to the performance of the best chamber music by proficients brought from various parts of the world; these concerts soon became a permanent part of the Society's work, attracting many members to the Society, and undoubtedly doing much for the advance of musical culture in Dublin.
It would be impossible here to estimate adequately Stoney's influence upon the Royal Dublin Society. The work of reorganisation arising in its constitutional changes was enormous. One who, like the writer, served in the secretaryship during more settled times, can realise what it must have been. The Council is a complex body, sitting together as a Council, working apart as three great Committees of Agriculture, of Science and its Industrial Applications, of General Purposes. There are two secretaryships, which generally are regarded as respectively apportioned to Agriculture and to Science. The latter was filled by Stoney, but the secretaries' work is by no means limited by this subdivision. They enter alike into all the questions of public policy continually arising, and into the Financial Committee's supervision of ways and means.
Additional to his general work for the Society Stoney worked whole-heartedly for the advancement of its scientific functions. For many years his own research work was communicated almost exclusively to the Society, and published in its ' Proceedings' and 'Transactions': his aim being to confer upon its publications something more than a local prestige.
His gifted relative, George Francis FitzGerald, ably assisted him in this endeavour. The younger men, feeling the advantages of discussions in which men of such critical ability participated, gladly brought their work to the Society, and for many years the evening meetings were characterised by debates of the highest scientific interest. Although the Society still does invaluable work for science, there is no doubt that in the untimely death of FitzGerald, and the loss of Stoney upon his departure to London, the science meetings lost much of their high standing.
The close of his official work in Dublin meant for Stoney a time of leisure; but it came too late for the publication of much of the scientific work he had done. He was then nearly 68 years of age, with health impaired by the long and heavy strain of official work. His life in London was largely devoted to the completion and publication of original work begun in earlier years; but this could only be slowly accomplished, and he died before it was completed according to his wishes.
Stoney's scientific work needs no apology on the score of diversity or of prolificness; but the amount of it conveys but a small idea of his life's work, and, indeed, forms but a small part of it. Only an over-mastering scientific enthusiasm could have elicited such a body of work from a man harassed for the best years of his life by strenuous duties continually leading his thoughts into other channels. Yet a major part of his work was accomplished during those years of official toil. He was a remarkable instance of the resistless power of a great intellectual development; of its relentless pertinacity and resolution. His power of accomplishment was linked with an unusual degree of self-centred devotedness to the immediate subject of his thoughts and speculations. Around this subject the interests of his intellectual life appeared to be gathered and concentrated for the time. With this very conspicuous quality of mind it is more remarkable that he worked as a devoted and successful official during years of considerable scientific fertility. It must have been a heavy exaction even from one with his high-minded sense of duty. The final facts of his success in both spheres of his work demonstrate at once his intellectual force and his splendid devotion to his aims and to his duties.
One of Stoney's earliest papers was a geometrical examination of the conditions of propagation of undulations of plane waves in media (' Trans. Roy. Irish Acad.,' vol. 24, 1861). The reasoning is mainly directed to explaining, why an undulation of the kind considered, when once established, continues to propagate itself in one direction only.
Analytical reasoning is not used. Indeed, throughout a major part of his writings Stoney prefers geometrical to analytical reasoning. In a later paper he states his preference for the former: " The chief value of the geometrical form of proof is that it gives us a more continuous view of what is going on in nature, inasmuch as the stages of the geometrical proof of a physical problem keep throughout their whole progress in close proximity to what actually takes place, whereas a symbolical proof is in contact with nature only at its commencement and at its close " (" On a New Theorem in Wave Propagation," 'Phil. Mag.,' April, 1897).
After the appearance of his optical paper on 1861 the subject of geometrical optics does not appear to have enjoyed Stoney's attention till the appearance of the " Monograph on Microscopic Vision " ('Phil. Mag.,' October, November, and December, 1896), that is, till after his official life was closed and he had leisure to work up material which, as in this case, had probably been by him for many years. The study of microscopic vision is based upon a method of resolution into flat wavelets. Stoney shows that the method is one of wide generality, and a series of propositions occupy a large part of the paper, establishing and analysing the fundamental proposition that " however complex the contents of the objective field . . . the light which emanates from it may be resolved into undulations, each of which consists of uniform plane waves," or wavelets, which do not undergo change as they advance. On this basis the causes of the phenomena presented by microscopic vision are sought in a paper ingenious in reasoning and laborious in its scope. The proof of the fundamental proposition given in the first paper did not, however, satisfy Stoney, and several subsequent papers appeared, one criticising an insecure proof advanced by Thomas Preston, " On a Supposed Proof of a Theorem in Wave-Motion" (Phil. Mag.,' May, 1897); also, on this subject, see ' Phil. Mag.' for February, April, July, and August, 1897, and July, 1898. A proof of the theorem by the principle of reversal is given in a paper published at p. 570 of the ' Report of the British Association ' for 1901; and Stoney returns to the matter again in the ' Philosophical Magazine' of February, 1903, this time partly with a view to welcome an analytical proof of the resolution into flat wavelets by E. T. Whittaker. This paper, entitled " How to Apply the Resolution' of Light into Uniform Undulations' of Flat Wavelets to the Investigation of Optical Phenomena," contains several theorems not contained in earlier papers. All this work was written in ignorance of the fact that Stokes, in one of his earlier papers (1845), had enunciated the same fundamental proposition from which Stoney's work takes origin—but without offering any proof. In a paper contributed to the ' Philosophical Magazine ' in April, 1905 (" Flat-Wavelet Resolution, Part III "), Johnstone Stoney announces his discovery of Stokes' priority. It is probable that Sir George Stokes considered it almost self-evident as a general statement " . . . for we may represent an arbitrary disturbance in the medium as the aggregate of series of plane waves propagated in all directions.'' In an appendix to this paper of April, 1905, Stoney again considers the proof of the theorem, and from a manuscript note inserted in his " Monograph on Microscopic Vision " it would appear that the last mode of regarding the matter was that which he preferred.
Stoney's last published scientific papers were on telescopic vision (' Phil. Mag.,' August, November, and December, 1908), and these are now referred to because they are a continuation of the subject to which Stoney directed his attention early in life—consideration of wave-propagation and the formation of images. In treating of telescopic vision Stoney resolves the light before it enters the telescope into a somewhat special system of undulations of spherical wavelets, i.e. into spherical undulations, the centres of which shall be the several points of a plane perpendicular to the optic axis and situate close in front of the objective, and by the interference of which (in the usual manner), at the principal focus, the image is formed; the papers are of the same character—at once ingenious and laborious—as that upon microscopic vision. It is a surprising reflection that Stoney was in his eighty-third year when these elaborate and painstaking papers were penned.
The papers alluded to above represent important work, and are characteristic of Stoney's manner of dealing with investigations of similar description. Their inception dates from the beginning of his scientific career, and they have, therefore, been placed in the forefront of this brief review of his work, but they are by no means the most important part of his work. His investigations in various departments of molecular physics distinctly claim that place.
Stoney s work in molecular physics began in 1860, when, on the basis of Maxwell's estimate of the average length of the free path of the molecules of a gas, he made an estimate of the number of molecules present in unit volume. This was, of course, led up to also by the work of Clausius, and was an early contribution to a great subject, then only beginning to be a subject of research. Waterston's memoir had been submitted fifteen years earlier (1845), and, not being published, the advent of the new ideas had to wait for Clausius' papers of the later years of the forties. For the first time the kinetic theory then received publication, and it was recognised that planetary conditions as regards freedom of motion might attend the movement of a gaseous atom between its encounters. Stoney showed a clear and vivid appreciation of the new molecular science and from this time forward the application and exposition of its laws occupied him at intervals throughout his life. We gather some idea of the state of the subject by perusing a paper by Stoney appearing in the 'Proc. Roy Irish Acad,' vol. 7, 1858. This appears to be his earliest contribution to the subject. We find him demonstrating that the law of Boyle is contrary to the view that the particles of a gas are at rest, or that it can be a continuous homogeneous substance.
Ten years later, writing in the ' Philosophical Magazine ' " On the Internal Motions of Gases Compared with the Motions of Waves of Light" (' Phil. Mag.,' August, 1868), we find him complaining that the dynamical theory of gases had not met with the general attention and acceptance which it deserved. In this latter paper a vivid appreciation of the relative magnitudes is shown, and Stoney pictures the source of the light waves as existing in the "from fifty to one hundred thousand of these little orbital revolutions " which the molecules are able to execute between successive encounters. Such thoughts were more fully elaborated later. He closes his review of the subject with his estimate of molecular numbers in a gas at standard pressure and temperature, concluding that in 1 cubic mm. there are 10-18 molecules.
Arising out of his interest in the kinetic theory of gases are his series of papers on the conditions limiting planetary atmospheres. He first touches on the subject in his paper " On the Physical Constitution of the Sun and Stars," which appeared in the ' Proceedings ' of the Royal Society in 1868. In this he infers that a complex atmosphere will, near its outward quiescent boundaries, cease to be homogeneous, the lighter constituents extending further into space. Towards the close of 1870, in a discourse delivered before the Royal Dublin Society, the subject of the absence of atmosphere from the moon is discussed, the conclusion being that the gravitation on the moon will not suffice to retain a free molecule moving in a radial, or even outward, direction, with a velocity of 2.38 kilometres per second. Molecules which occasionally reach this speed may be, accordingly, lost to the moon. A full account of his views is given in his paper " On Atmospheres of Planets and Satellites" (Trans. Roy. Soc. Dub., vol. 6, 1897). Stoney contends that on the earth hydrogen and helium are scarce or absent because of their leakage from the atmosphere; water molecules, on the other hand, cannot attain so great an excess over the velocity of mean square as is required for their escape. The theory has been called in question on deductive reasoning (see papers by S. R. Cook, ' Astrophys-Journ. vol 11, Jan., 1900: and by G. H. Bryan, ' Phil. Trans.,' A, vol. 196, March, l900). Stoney's argument rests, as he admits, on inductive reasoning, based on the observed facts of the absence of atmosphere from the moon, and the scarcity of helium and hydrogen on the earth, and he meets the deductive objections by questioning the adequacy of the mathematical theory to include all the events which may lead to excessive velocities of isolated molecules in the upper atmosphere. The discussion is too long to enter upon here. In the limit we must accept as true that a small asteroid could not retain an atmosphere by its gravitational attraction; and the view, held by some, of an asteroidal origin of our earth would appear to meet considerable difficulty here, more especially with regard to the existence of the terrestrial hydrosphere. There is no doubt that Stoney's theory removes difficulties in explaining the absence of a lunar atmosphere. It has been applied, too, to the condition apparently obtaining on Mars. However, it must be admitted that other causes may exist to account for the condition obtaining in those bodies.
The discovery by Crookes that a blackened vane suspended in a high vacuum is repelled by radiant heat or by light led to various suggestions as to the cause of the phenomenon. Stoney offered an explanation in harmony with the various experimental conditions which have to be fulfilled in order for the Crookes force to be developed. The theory of Stoney is given, in a some-what crude state, in the ' Phil. Mag. ' for March and April, 1876. Stoney's view may be summarised in the statement that for a certain distance in front of the heated vane, and reaching from it to the glass envelope, when the vessel is not too large, the molecular motions of the rarefied gas are polarised by the thermal conditions, and interpenetrate one another in a degree greater than prevails elsewhere in the gas. The greater molecular interpenetration in the line between glass and vane involves nothing of the nature of a wind, but determines a greater stress in the direction of polarisation. Errors in the earlier statements of his views are corrected in his paper in the Trans. Roy. Soc. Dub.,' 1878, and republished in the ' Phil. Mag.' of December, 1878; and a mathematical expression for the Crookes stress is given, based upon an investigation of Clausius of the stress across a layer of gas conducting heat normal to a heater and cooler. FitzGerald took a part in the discussion (cf. his ' Collected Papers ') by showing that the stress parallel to the heater and cooler could not be the same as the perpendicular stress—or, in other words, a polarisation stress must exist ('Nature,' vol. 17, p. 514)—and by a mathematical discussion of the subject in the ' Trans. Roy. Soc. Dub.,' 1878.
In 1874, in a paper ' On the Physical Units of Nature,' read before the Belfast meeting of the British Association, Stoney pointed out that, on the basis of Faraday's law of electrolysis, an absolute unit of quantity of electricity exists in that amount of it which attends each chemical bond or valency. This paper was printed afterwards in the ' Phil. Mag.' for May, 1882. He suggests that this might be made the unit quantity of electricity. He subsequently suggested the name electron for this small quantity. Von Helmholtz, in 1881, independently, drew attention to the existence of such definite elementary charges, which behave like atoms of electricity. Stoney estimated the magnitude of the electron in 1874, finding it to be equal to the unit (then the ampere) x 10-20. This is the same as 1 C.G.S. electrostatic unit x 3x10-11. In this estimate he avails himself of his determination of the number of molecules present in 1 cubic mm. of a gas at standard temperature and pressure, viz., 10-18. That the result should suffer from the errors in the then available data detracts nothing from the merit of Stoney's performance. It was pioneer work in an obscure and difficult line of research.
The conception of one or more unit charges of electricity within the atom was soon applied by Stoney to the phenomena of spectral dispersion. Maxwell's ideas on the electromagnetic nature of light were first published in 1862 and 1866, but the final statement of his theory only appeared with his great work on ' Electricity and Magnetism ' in 1873. In Stoney's first paper, which deals with the " Internal Motions of Gases compared with the Motions of Waves of Light," which appeared in the ' Philosophical Magazine ' for August, 1868, no reference to Maxwell's views is made, nor is there, of course, any suggestion of the electronic origin of light waves. The aim of the paper is to point out that there must be periodic motions within the " molecule " to occasion the spectral lines, motions distinct from those translatory ones which are affected by the temperature of the gas. The latter are irregular, the former are in general regular, save at the instant of collision—an instant short in comparison with the time occupied in describing the mean free path. The causes of continuous and band spectra are referred to. The nature of the internal motions must differ in different gases. A further step is taken in his paper of January, 1871 (' Proc Roy Irish Acad ') The internal atomic motion is a complex periodic motion which, however, is resolvable into harmonics If we assume the undulation arising in the ether to consist of periodic plane waves, then, whatever its form, it may be regarded as formed by the superposition of simple pendulum vibrations, one of which has the full periodic time, while the others are harmonics of this vibration, which may be developed by Fourier's theorem. While these component vibrations are superimposed in free ether, on entering a dispersive medium the several vibrations no longer keep together, and a physical resolution is effected in the spectrum. Hence simply harmonic sequences of spectral lines would arise from the distinct motions in the molecule of the gas, for there may be several such motions, each producing its own series of harmonics. Applying these views to the case of the ordinary hydrogen spectrum, Stoney finds that the lines h, F, and C are nearly the 32nd, 27th, and 20th harmonics of a fundamental vibration whose wave-length in vacuo is 0.13127714 of a millimetre, this agreeing closely with Angstrom's measurements. A few months later, Stoney, in conjunction with Emerson Reynolds, advances yet further, finding a serial relationship, of the kind referred to above, in a large number of lines in the absorption spectrum of chlorochromic anhydride. But the general result as to the existence of simple harmonic relations was challenged by Schuster and others, on the ground of the theory of probabilities, the instances being held to be too few to establish a case. It was some years later that the observations of Huggins upon stellar spectra led to an extension of the hydrogen spectrum, as this had been observed in solar light; and in 1885 Balmer showed that a comprehensive law for the whole system of hydrogen lines was expressible in a single formula of quite different type; and a train of ideas was thus introduced, which has led to much subsequent work directed to the sorting out of related series in the lines of a spectrum.
Stoney, in his principal paper on this subject (' Trans. Roy. Soc. Dub.,' vol. 4, May, 1891), states his electronic theory of the origin of the complex ether vibrations which proceed from a molecule emitting light. The paper is " On the Cause of Double Lines and of Equidistant Satellites in the Spectra of Gases." His theory is based on the electromagnetic theory of light, and refers a series of spectral lines to the periodic motion of an electron in the atom or molecule, the elliptic partials into which this motion may be resolved by Fourier's theorem accounting for the several lines. If perturbing forces exist an apsidal motion may affect the elliptic partials, and Stoney shows that, while the undisturbed orbit will in general be such as to give rise to a definite series of single lines in the spectrum, the consequences of an apsidal motion affecting some, or all, of its partials is to cause the corresponding lines of the series to become double. He deduces, on these views, the result that the double D lines of sodium in the solar spectrum might be accounted for by the motion in each molecule of an electron in an elliptic orbit having an axial ratio lying between 11 to 1 and 13 to 1, round which ellipse the electron revolves 169,637 times in a "jot" of time, the ellipse being slowly shifted round with an apsidal motion which carries it once round while the electron performs 1984 revolutions. Similarly, precessional motion will occasion triple lines. The "jot " of time is the time light takes to traverse one-tenth of a millimetre in vacuo.
A very large amount of work has been done by mathematical physicists within recent years on theories of atomic structures involving the electron in motion; and, again, the importance of the electron in views on the phenomena of the vacuum tube, and on radioactivity, is known to all. Atomistic ideas as to the nature of electricity were, of course, held before Stoney's views were expressed, but there was a period when the continuous theory had largely displaced the atomistic view. This seems to have arisen mainly from Maxwell's teaching. The more recent and, it must now be admitted, more helpful atomistic theory, in its modern development, dates back to the finding of the electron in Faraday's law of electrolysis by Stoney and Helmholtz; and Stoney's use of the electron in a light-giving atom is one of the earliest developments, showing the availability of the conception of a small discrete particle of electricity. This, in the present writer's opinion, is Stoney's most important work for science. It may be that a very different conception of intra-atomic structure will ultimately prevail, but the moving electron as a constituent part has not as yet found a good substitute. The phenomena of radioactivity have strongly confirmed it. The early work of Thomas Preston on the Zeeman effect also confirms it. Such recent views as those of Ritz, on atomic structure and the explanation of the Zeeman phenomena, assume, indeed, other sources of action and reaction within the atom, but the electron still remains as generator of electromagnetic waves. And even if the electron ultimately yields place to new conceptions it has helped to forward investigation in many lines of research, and those who first gave it to theoretical science have taken a worthy part in the advance of man's knowledge of Nature. The early date of Stoney's work and the clearness and the fullness with which he urged his views certainly entitle him to a leading place among those pioneers.
Stoney gave much time and thought to the subject of the units of physical science and their nomenclature. He served upon the Committee of the British Association for the selection and nomenclature of dynamical and electrical units in 1873—a committee whose recommendations have been very generally accepted. His paper "On the Physical Units of Nature," which was read before the Belfast meeting of 1874, has already been referred to. In it he urges the claims of " the single definite quantity of electricity " observed in electrolysis as a unit of electrical quantity. The paper is printed in the ' Proceedings ' of the Royal Dublin Society, 1881. Several other papers relating to the subject of units came from his pen, and throughout his many papers bearing on other subjects he frequently suggests new departures in nomenclature. Indeed, it may be said that his desire for the perfection of brevity and reasonableness introduces some difficulties in the study of his papers, seeing that in some cases an unwonted nomenclature has to be first acquired. His services to the subject of physical mensuration have, however, been great; and till quite late in his life he laboured to facilitate the introduction of the metric system into this country.
The circumstances of Stoney's early life led, as has been mentioned, to his appointment as observer to Lord Rosse at Parsonstown. The interest in astronomy then aroused remained with him throughout life. He wrote both on the instrumental equipment of observatories and on the objects of the heavens. Thus there are papers "On Collimators for Adjusting Newtonian Telescopes " (' B. A.,' 1869); " On the Equipment of the Astrophysical Observatory of the Future" ('Monthly Notices,' 1896); "On the Mounting of the Specula of Reflecting Telescopes" ('Proc. Roy. Soc. Dub.,' 1891). His other papers are principally upon the Leonids. In one of them, a discourse before the Royal Institution (1879), the idea of comets capturing meteorites in virtue of the retardation experienced by the latter when passing through the gaseous substance of the comet is put forward (see also 'Monthly Notices,' June. 1867) Other papers are upon the physics of the solar atmosphere; one of them has already been referred to, another was published in the 'Philosophical Magazine ' of December, 1868.
In 1888 Stoney entered upon a study of the numerical relations of the atomic weights An outline of his results appears in the ' Proceedings ' of the Royal Society, April, 1888. The full paper has not been published. The leading idea is that if a succession of spheres be taken whose volumes are proportional to the atomic weights (" atomic spheres "), and the radii of these spheres are plotted on a diagram as ordinates, and a series of integers as abscissae, a logarithmic curve, y = K log(qx), is developed which, in the belief of the investigator, shows that the atomic weights follow laws which can be represented as the intersection of two definite mathematical curves; implying that two definite laws of nature have to be coincidently fulfilled for an atom to come into existence. The curve so represented passes nearly through the positions given by observations. The discussion as to how to reconcile the curve with the slight perturbations, and why neighbouring logarithmic curves pursuing courses close to the observed positions are excluded, occupies several sections of the paper. He also gives a polar diagram in which the radii of the atomic spheres are used as radii vectores. This diagram suggested to him, in the first instance, the logarithmic spiral. The diagram is of much interest; and finds publication in the ' Phil. Mag.,' September, 1902. The quadrants of the figure are alternately found to include electro-positive and electro-negative elements. An unoccupied sesqui-radius appears in the diagram at a place where alone an abrupt transition from the electro-positive to the electro-negative character is observed. The inert gases discovered some years later now occupy this radius. In the 'Phil. Mag.' of September, 1902, Stoney suggests that the unusual chemical behaviour of these new elements is a consequence of their occupying a position between the halogen radius, in which the electro-negative condition attains its greatest intensity, and the radius containing lithium, sodium, potassium, rubidium, and Caesium, which are the most electro-positive of the elements. The prediction of missing elements on the indications of the logarithmic law is notified specially by Stoney in a letter to the ' Phil. Mag,' October, 1902. He suggests here that the new elements will possess the greatest atomic volumes among the elements in the solid state. The specific gravity in the solid state of these bodies has not as yet been determined.
There is no doubt that the logarithmic curve given by Stoney is suggestive in the highest degree, and is a most interesting contribution to this subject. Stoney had the matter very much at heart, and the non-appearance of his full paper evidently caused him much pain. Stoney believed that a mistaken view was taken of what he really aimed at, this belief being supported by a note of Sir George Gabriel Stokes appearing in ' Stokes' Scientific Correspondence,' Vol 1, p. 219. In the month of March, 1911, Stoney, then upon his death-bed and already worn with many months of illness, dictated a memorandum on the mathematical principles which influenced him in his work upon the logarithmic law of the elements. There is no sign of failing power in this memorandum. Extracts from the original manuscript were in consequence made by Lord Rayleigh, and were communicated by him and published in the 'Proceedings' of the Royal Society (A, vol. 85, p. 471, July, 1911). In these extracts the spiral curve is again reproduced.
A considerable number of scientific subjects, additional to those already referred to, engaged Stoney's attention at various times. They range over a wide field of scientific enquiry and often show much originality. In the ' Phil Mag.' for April, 1390, he suggests that bacteria may derive a part of their life-energy by relations towards the faster moving molecules in the surrounding medium, of a selective nature, so that they escape the second law of thermodynamics much as the Maxwell demon might have done. A very different topic is " The Magnetic Effect of the Sun or Moon on Instruments at the Earth's Surface" ('Phil. Mag.,' October, 1861); also " On the Energy Expended in Driving, a Bicycle," in conjunction with his son, Mr. G. Gerald Stoney, F.R.S. ('Trans. Roy. Dub. Soc.,' 1883); Address to the Mathematical and Physical Section of the British Association, 1879; "On Denudation and Deposition" (Phil. Mag.,' April and June, 1899), etc.
Johnstone Stoney served on several Committees of the British Association. His name appears in Reports on Solar Radiation, Catalogue of Spectral Rays, on papers connected with Spectrum Analysis, 1881; and he acted as reporter of a lengthy compilation of the Oscillation-frequencies of Solar Rays, 1878.
The subject of Ontology engaged his attention for a considerable time: a paper " On the Relation between Natural Science and Ontology" was communicated by him to the ' Proceedings ' of the Royal Dublin Society in 1890. This paper is in the highest degree characteristic at once of Stoney's mental attitude towards Nature, his methods of logical analysis, and the tendency he so often shows of a desire to build up a subject in its entirety and from first principles, framing for the purpose new words and new definitions. As already remarked, the tendency to revising the ordinary use of language so as to give it more direct significance and more convenient form often imposes some labour upon his readers The ontology paper is a really profound and exhaustive review of the subject, and indicative of keen introspection, but it is difficult reading on account of the large amount of definition which the writer deems essential. A second part of the essay was published in 1903 by the American Philosophical Society. An earlier allied essay is " On how Thought presents itself among the Phenomena of Nature," being a discourse delivered before the Royal Institution, February, 1885. A few papers on what may be called abstract physics may be mentioned here " Survey of that Part of the Range of Nature's Operations which Man is Competent to Study" ('Proc. Roy. Soc. Dub,' 1899); " On Texture in Media and on the Non-existence of Density in the Elemental Ether" ('Proc. Roy. Soc.,' 1890); "Curious Consequences of a well-known Dynamical Law " (' Proc. Roy. Soc. Dub.,' 1887), etc.
Stoney was keenly alive to the charm and refining influence of music, and, as already stated, did much for the study of music under the auspices of the Royal Dublin Society. He wrote a paper " On Musical Shorthand,' and in the same volume (1882) of the 'Proceedings' of the Royal Dublin Society is one on methods of dealing with echoes in rooms. In 1883 he suggests, in the same journal, a mode of prolonging the tones of a pianoforte.
Enough has now been said with reference to his scientific work to show how wide in scope it was. Stoney wrote on other subjects, however: " On the Demand for a Catholic University " ('Nineteenth Century,' February, 1902): and in the interests of his University, he writes upon the subject of its reform in 1874, and speaks in its defence against the legislation which threatened it in 1907. As late as 1910 he printed a thoughtful pamphlet on " The Danger which in our Time threatens British Liberty."
No man ever lived more completely and devotedly for his ideas than did Johnstone Stoney. He was the type of the philosopher. Nothing could check his ardour for research; no labour was too great for him to undertake in the pursuit of his ideas. In spite of heavy office-work, which afforded none of the long-vacation leisure of university life, in spite of the absence of that stimulus which comes from a professional scientific life, Stoney published two or three papers each year. Through his middle life he rose at five o'clock in order to get in some scientific work before starting for his office. He was never a very strong man, and this necessitated much restraint as to evening society functions. His Sundays were largely devoted to experiments or writing. His annual holiday was usually for the ten days of vigorous intellectual life of a British Association meeting. At all times he greatly grudged the time and labour of writing down and putting through the press work which had been a pure delight to carry out.
0f the moral attributes of Johnstone Stoney it is impossible to speak without a feeling of profound respect. His fearless love of truth was bound up with an ideal rectitude of life. He stood above all creed that could not appeal to the rationality of man and that denied the continuity of Nature's laws. Intellectually superior to most men, he was yet at once too great and too benevolent to criticise the littleness of the many, the shallowness of their minds, and the fallacies of their tenets. This did not arise in abstraction from the struggle of life and its troubles, for no more sympathetic and kindly man ever breathed. He championed every earnest effort, more especially endeavouring to forward the interests of the younger scientific men with whom he came in contact, in this respect meting to others that same treatment which he himself received at the hands of his early and life-long friend, the Earl of Rosse. Stoney's word was a law to him: what he promised he performed. This is a moral quality which soon gets known, and confers a just influence upon its possessor, not only with those who also possess it, but again with those deficient in it. When Stoney left Dublin, and the occasion was taken by the Royal Dublin Society to present him with a memento of his work for the Society, and again when he received their Boyle Medal, the recognition of his high moral qualities was in the minds of all, and could not be kept out of analyses which were intended to embrace only his social and scientific work.
George Johnstone Stoney received many distinctions during his long and laborious life. Probably the one he most highly valued was the receipt of the first Boyle Medal from the Royal Dublin Society. The medal had just been founded to commemorate the great Irishman who had so large a share in the initiation of the parent scientific society of this country. It was felt by the Council of the Royal Dublin Society that Stoney, above every other Irishman then living, merited the distinction of having his name placed first upon the roll. It was conferred upon him in 1899. He was a Foreign Member of the Academy of Science at Washington, and of the Philosophical Society of America founded by Franklin. He was a corresponding member of Sci. di Lettere ed Arti di Benevento. He was President of Section A at the meeting of the British Association in 1879. He served as Vice-President of the Royal Society under Lord Lister, and also served upon the Council, 1898-1900.
Stoney married his cousin Margaret Stoney. He leaves two sons and three daughters. His eldest son has risen to distinction as an engineer, having been collaborator in the development of the steam turbine with the Hon. Sir Charles Parsons, K.C.B., F.R.S., and is now manager in the Parsons Turbine Works. One daughter is a Lecturer at the London School of Medicine for Women, and another daughter is a London physician. George Johnstone Stoney died in the eighty-sixth year of his age, on July 5, 1911, after a long illness. His body was cremated, and his ashes buried in the graveyard of the little suburban town of Dundrum, Co. Dublin.
In stature, he was tall; in bearing, dignified; and his features and expression revealed at once his intellectual power, his nobility of character, and his kindly and sympathetic disposition. The portrait prefixed to this memoir was taken in the year 1910, in the eighty-fifth year of his age. It is in every way faithful and excellent.