FitzGerald, George Francis

(1851-1901), physicist

by Bruce J. Hunt

© Oxford University Press 2004 All rights reserved

FitzGerald, George Francis (1851-1901), physicist, was born on 3 August 1851 at 19 Lower Mount Street, Dublin, one of at least six children of William FitzGerald (1814-1883), clergyman, and Anne Frances (d. 1859), daughter of George Stoney of Oakley Park, King's county, Ireland.

Education and marriage
A product of the small but active intellectual wing of Ireland's protestant elite, his life centred closely on Trinity College, Dublin. At the time of FitzGerald's birth his father was professor of moral philosophy there, as well as vicar of a Dublin parish; he later served as bishop of Cork and, from 1862, of Killaloe, and was regarded as the most distinguished prelate in the Church of Ireland. On his mother's side FitzGerald's uncles George Johnstone Stoney and Bindon Blood Stoney also attended Trinity College, Dublin, where they excelled in science. Both later became fellows of the Royal Society, and FitzGerald's 'Uncle Johnstone', himself a noted physicist, had a strong influence on his nephew's work and thought.

FitzGerald's otherwise happy childhood was darkened by the death of his mother when he was eight. Along with his brothers Maurice and William and sisters Anne, Beatrice, and Edith he was educated at home by private tutors. Maurice (1850-1927) became professor of engineering at Queen's College, Belfast, while Willy (1852-1919), later a clergyman at Killaloe, is remembered as the illustrator of an early book by Bram Stoker. Anne (1847-1890) became superintendent of the City of Dublin Nursing Institution, while Edith married E. P. Culverwell, a mathematician and fellow of Trinity College, Dublin.

FitzGerald entered Trinity College, Dublin, in 1867 at sixteen. Maurice, who entered the same year, later recalled that his brother was 'almost from the very first, first of first honours' (Hunt, 6), particularly excelling in geometry. After graduating at the head of his class in mathematics and experimental science in 1871, FitzGerald settled down, 'after the manner of the pick of the Dublin men' (Larmor, 445), to further study with an eye to winning a much prized Trinity College fellowship. He spent the next six years reading deeply in physics and philosophy, acquiring a mastery of mathematical techniques and a permanent regard for the teachings of 'the great and good Bishop Berkeley' (Scientific Writings, 376). He won a fellowship on his second try in 1877 and soon took up duties as a college tutor; in 1881 he was named Erasmus Smith professor of natural and experimental philosophy, a post he retained until his death. An enthusiastic teacher, he worked hard to promote student work in experimental physics, though the laboratory facilities at Trinity always remained inadequate. He was popular with undergraduates, but faced opposition from senior fellows of the college, who successfully resisted his repeated efforts to reform its administration.

On 20 December 1885 FitzGerald married Harriette Mary (1860-1919), daughter of the Revd John Hewitt Jellett (1817-1888), himself a former professor of natural philosophy at Trinity College, Dublin, and from 1881 its provost. They had five daughters and three sons, to whose education FitzGerald devoted great time and attention. Their eldest son, Raymond (1890-1964), was later knighted for his management of an Indian railway.

FitzGerald was tall and athletic, with a full beard and a high forehead. He was known for his generosity with his time, his wit, and above all his remarkable agility of mind. 'He had, undoubtedly, the quickest and most original brain of anybody', his friend Oliver Heaviside later said, adding that this was not always a help when it came to securing scientific fame: 'He saw too many openings. His brain was too fertile and inventive' (Larmor, 446). Instead of following one of his many ideas through to a definite conclusion, FitzGerald would usually hit on some new possibility and set off after that instead. His talents lay not in the quiet construction of comprehensive theories but in the give and take of discussion and criticism. As a result some of his most important contributions to science appeared not in his own writings but in those of friends and colleagues whose thinking he had stimulated.

Electromagnetic research
One of FitzGerald's few pieces of sustained work came at the beginning of his career. Spurred by John Kerr's 1876 discovery that reflection from the polished pole of a magnet altered the polarization of a beam of light, he sought to develop a general electromagnetic theory of reflection, a task which James Clerk Maxwell had left aside in propounding his otherwise impressive electromagnetic theory of light. FitzGerald was well equipped to fill this gap: not only was he intimately familiar with Maxwell's 1873 Treatise on Electricity and Magnetism, but, in preparing for the Trinity fellowship competition, he had closely studied the 1839 optical theory of his Dublin predecessor, James MacCullagh, in which the ether that carried the waves of light was treated as resisting the absolute rotation of its parts rather than their simple displacement. In a long paper he sent to the Royal Society late in 1878 FitzGerald showed that when MacCullagh's equations were translated into Maxwell's electromagnetic terms, they brought along the full theory of reflection. The result, as Maxwell himself noted in his referee report (written shortly before his death in 1879), was a significant extension of the electromagnetic theory of light, as well as the introduction of a suggestive analogy between the electromagnetic field and MacCullagh's rotational ether.

By the end of the 1870s FitzGerald was emerging as a leading student of Maxwell's electromagnetic theory and one of the most creative explorers of the possible mechanical structure of the ether. He still made false steps, however. In 1879 Oliver Lodge, an English physicist who was to become his close friend, suggested several ways in which high frequency electrical oscillations might be used to generate electromagnetic waves like those which Maxwell had identified with light. FitzGerald not only criticized Lodge's specific proposals, but, misled by a remark of Maxwell, threw cold water on the whole idea of generating waves in the ether by any purely electromagnetic means. Lodge dropped his idea and did not take up the search for electromagnetic waves again until 1888. FitzGerald soon found his own error, however, and published a series of papers in 1882-3 in which he not only showed that the discharge of an ordinary capacitor would produce electromagnetic waves, but calculated their wavelength and even showed how the radiated energy would vary with the frequency. In 1885 he also devised and built a model of the ether, an array of brass wheels linked in pairs by rubber bands, which he used to illustrate how electromagnetic waves could be generated and how their energy would travel through the ether. By the mid-1880s FitzGerald had a good grasp of the theory of electromagnetic waves; the remaining difficulty, as he told J. J. Thomson, was to find a detector: 'something to feel these rapidly alternating currents with' (Rayleigh, 22).

FitzGerald was thus primed to respond to any experimental evidence for the existence of electromagnetic waves. When in early 1888 the young German physicist Heinrich Hertz published his first tentative accounts of the detection of such waves with a sensitive spark gap, FitzGerald pounced on the news. As president for that year of the physics section of the British Association for the Advancement of Science, he was well placed to bring the discovery to wider notice, and he used his address at the September meeting at Bath to praise Hertz's 'splendid result' (Scientific Writings, 237), which he made a point of identifying as confirmation of Maxwell's theory. FitzGerald and his assistant F. T. Trouton also repeated and extended Hertz's experiments and, in January 1889, were among the first to demonstrate them publicly.

At the 1888 Bath meeting FitzGerald also drew attention to the then little known writings of Oliver Heaviside (1850-1925), an eccentric former telegrapher who had taken up Maxwell's theory several years before. FitzGerald was among the first to recognize the merits of Heaviside's powerful but idiosyncratic methods, and his enthusiastic endorsement of Heaviside's work, particularly in an 1893 review of his collected Electrical Papers, played an important part in winning it a wider audience and in installing Heaviside's set of four vector equations as the standard form of Maxwell's equations. FitzGerald and Heaviside also struck up a lively correspondence that lasted until FitzGerald's death. Along with Lodge they formed the core of the Maxwellian group that effectively guided the interpretation and assimilation of Maxwell's theory in the late 1880s and 1890s.

Electron theory
One of FitzGerald's most important contributions to electrical theory came in what was in effect a collaboration with his friend and fellow Irishman Joseph Larmor. When in late 1893 Larmor sent the Royal Society an ambitious paper proposing to extend MacCullagh's rotational ether into a complete theory of matter and electromagnetism, FitzGerald was called upon as a referee. Dropping the veil of anonymity, he fired off a series of letters to Larmor, pointing out flaws in his initial formulation and pushing him toward including in his scheme subatomic electric charges, conceived as isolated singularities in the ether. As Larmor revised and elaborated his theory in the summer of 1894 and in a series of subsequent publications, such 'electrons' (a word FitzGerald had borrowed from Johnstone Stoney) soon emerged as its centrepiece. Though physicists quickly recognized the importance of Larmor's electron theory, few ever realized how large a part FitzGerald had played in its birth and development.

While FitzGerald's work on electron theory foreshadowed the direction physics would take in the twentieth century, his commitment to a mechanical ether reflected his firm roots in nineteenth-century traditions. FitzGerald was especially drawn to the hypothesis, which he had first advanced in 1885, that the ether was ultimately a perfect liquid filled with fine-grained turbulent motion. Although he recognized the mathematical obstacles facing any effort to demonstrate that such a vortex sponge would exhibit the properties required of the electromagnetic field, FitzGerald remained, he said, 'horribly confident that it is the theory of the ether'. 'I have a sort of feeling in my bones that it must be so', he told Heaviside in 1893; 'I suppose I am a bit a crank upon it' (Hunt, 103).

Contraction hypothesis
FitzGerald's posthumous fame has rested largely on his contraction hypothesis, later an important part of Einstein's theory of relativity. In 1887 the American scientists A. A. Michelson and E. W. Morley used an interferometer to search for the slight effect that, on prevailing theories, the ether wind arising from the motion of the earth was expected to have on a beam of light. Despite the extreme delicacy of their apparatus they found no such effect. While discussing Michelson and Morley's result with Lodge in the spring of 1889, FitzGerald hit on a surprising way out of the seeming contradiction: perhaps, he said, motion through the ether affected the interferometer itself, causing it to contract just enough to compensate for the expected effect of the ether wind. FitzGerald's hypothesis has often been depicted as purely ad hoc, but he in fact had good reason, based on a formula Heaviside had recently found for the electric field around a moving charge, to think that motion through the ether might alter the forces between the particles that made up the interferometer by just the amount needed to produce the required contraction. In May 1889 FitzGerald sent the American journal Science a brief letter describing his hypothesis, but never saw it in print. He did, however, persuade Lodge to mention the idea in papers he published in 1892-3, where it came to the attention of the Dutch physicist H. A. Lorentz, who had formulated a similar hypothesis independently in 1892 in connection with his electrical theory of matter. FitzGerald was happy to share credit for an idea that many of his colleagues had initially dismissed as far-fetched, and it soon came to be known as the FitzGerald-Lorentz contraction. In 1905 Albert Einstein put it on a new basis, without reference to the ether, in his theory of relativity.

Other work
Besides his main work on the ether and electromagnetism FitzGerald published papers on subjects ranging from electrolysis to aeronautics. He purchased and tried to fly a Lilienthal glider, and it has been speculated that the young James Joyce's invention of the character Stephen Daedalus owed something to the sight in 1895 of FitzGerald running with his set of wings down the Trinity College cricket pitch (Kenner, 268). Elected a fellow of the Royal Society of London in 1883, FitzGerald was awarded one of its royal medals in 1899. He served as honorary secretary of the Royal Dublin Society from 1881 until 1889, when he resigned after a proposal to raise its scientific level was defeated. A strong proponent of Irish industrial development and, from 1888, a leading member of the board of Irish national education, he pushed hard for the reforms of manual and practical instruction instituted in 1900. He reportedly declared that he intended to devote his remaining years to educational reform rather than scientific research, saying that whether the structure of the ether was solved now or fifty years hence was a small matter compared to the urgent task of lifting the Irish people out of their current state of scientific ignorance.

FitzGerald long suffered from recurring digestive troubles, and though they left him prematurely grey and looking older than his years, he was usually able to shake them off and resume his customary vigor. In autumn 1900, however, he was struck by a more serious attack, and when enforced rest and other treatments proved unavailing, an operation was attempted on 22 February 1901. An ulcer was removed, but his strength had been sapped and he died a few hours later at his home, 7 Ely Place, Dublin. After a large funeral at the Trinity College chapel on 26 February, he was buried at Mount Jerome cemetery.

FitzGerald wrote no books, but his scattered shorter works--'not large in bulk', in Heaviside's words, 'but very choice and original' (Larmor, 446)--were collected by Larmor and published in 1902 as The Scientific Writings of the Late George Francis FitzGerald. His friend and colleague John Joly declared the striking photographic portrait that forms its frontispiece to be 'absolutely faithful' (Joly, 515).

BRUCE J. HUNT

Sources  
The scientific writings of the late George Francis FitzGerald, ed. J. Larmor (1902)
J. L. [J. Larmor], Nature, 63 (1900-01), 445-7
O. J. Lodge, The Electrician (1 March 1901)
F. S. Trouton, Journal of the Institution of Electrical Engineers, 30 (1900-01), 1244-6
J. Larmor, Physical Review (May 1901)
O. J. Lodge, Yearbook of the Royal Society (1902)
The Times (25 Feb 1901)
Irish Times (25 Feb 1901)
The Athenaeum (2 March 1901), 277-8
B. J. Hunt, The Maxwellians (1991)
Lord Rayleigh [R. J. Strutt], The life of Sir J. J. Thomson (1943)
J. J. [J. Joly], review of FitzGerald, Scientific writings, London, Edinburgh, and Dublin Philosophical Magazine, 6th ser., 4 (1902), 513-15
'Fitzgerald, William', DNB
'Stoney, George Johnstone', DNB
J. Z. Buchwald, From Maxwell to microphysics: aspects of electromagnetic theory in the last quarter of the nineteenth century (1985)
S. G. Brush, 'Note on the history of the FitzGerald-Lorentz contraction', Isis, 58 (1967), 230-32
J. G. O'Hara and W. Pricha, Hertz and the Maxwellians (1987)
H. Kenner, A colder eye: the modern Irish writers (1983)
D. H. Akenson, The Irish education experiment: the national system of education in the nineteenth century (1970)
R. B. McDowell and D. A. Webb, Trinity College, Dublin, 1592-1952: an academic history (1982)
R. ffolliot, The Pooles of Mayfield and other Irish families (1958)

Archives  
Royal Dublin Society
TCD, department of physics
TCD, Old Library
TCD, papers |  CUL, corresp. with Lord Kelvin
CUL, letters to Sir George Stokes
CUL, J. J. Thomson Collection
Deutsches Museum, Munich, H. R. Hertz Collection
Inst. EE, archives, letters to Oliver Heaviside
Johns Hopkins University, Baltimore, Milton S. Eisenhower Library, H. A. Rowland Collection
RS, J. Larmor Collection
U. Birm., O. J. Lodge Collection
UCL, letters to Sir Oliver Lodge

Likenesses  
photographs, 1870-99, TCD
J. B. Yeats, charcoal, c.1878, TCD [see illus.]
group portrait, photograph, 1888 (with his wife's family), repro. in ffolliot, The Pooles of Mayfield
double portrait, photograph, 1890-1894 (with O. J. Lodge), U. Birm.; repro. in Hunt, The Maxwellians
Hollinger and Rockey, photograph, 1890-99, repro. in Larmor, ed., Scientific writings, frontispiece
print, TCD, Engineering School

Wealth at death  
£1357 17s. 6d. (in England): Irish probate sealed in England, 26 April 1901, CGPLA Eng. & Wales


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