Australian Dictionary of Biography

William Sutherland (1859-1911), by Jane Sutherland, c1911

La Trobe Picture Collection, State Library of Victoria, H27928

William Sutherland (1859-1911), theoretical physicist and physical chemist, was born on 24 August 1859 at Glasgow, Scotland, son of George Sutherland, woodcarver, and his wife Jane, née Smith. The family, which migrated to Sydney in 1864 and settled in Melbourne in 1870, was close-knit and encouraged intellectual and artistic pursuits. Alexander and George were William's brothers and Jane his sister.

Having attended Wesley College, in 1876 Sutherland enrolled at the University of Melbourne; he graduated (B.A., 1879; M.A., 1883) with first-class honours in natural science, and also completed course-work for the university's certificate of engineering. Instead of undertaking the year of supervised practical engineering required to complete the certificate, he proceeded to England to take up the Gilchrist scholarship which he had been awarded for further study in science at University College, London. He completed a B.Sc. in 1881 with first-class honours and the scholarship in experimental physics. During his course the professor of physics at University College, George Carey Foster, gave him his first experience of research.

Early in 1882 Sutherland, who had not enjoyed his time in Europe, returned to Melbourne. Seemingly without ambition for wealth or success, he devoted his life to reading and research. To support his modest needs, he did some private coaching and served as an examiner at the university. He was an unsuccessful applicant for the chairs of chemistry (1884) and physics (1885) at the University of Adelaide. When Melbourne's professor of natural philosophy, H. M. Andrew fell ill and died in 1888, Sutherland acted as lecturer until (Sir) Thomas Lyle arrived to take up the chair. Sutherland had also applied for this chair, but his application is reported to have been misfiled in London and thus not considered by the selection committee. In 1898 the chair of physics at the University of Sydney fell vacant, but Sutherland was deemed ineligible on account of age. When Lyle took leave in 1899 Sutherland was appointed acting professor. He augmented his income by writing for newspapers and from 1901 contributed regularly to the Melbourne Age, especially on scientific topics.

In 1885 Sutherland sent his first scientific paper to London for publication in one of the world's leading physics journals, the Philosophical Magazine, to which he subsequently became a prolific contributor. In all, he published seventy-eight scientific papers, mostly in major international journals. Because he had no access to laboratory facilities, his research was almost entirely confined to theoretical investigations, chiefly in the field of molecular dynamics. His approach was founded on the assumption that the particles of which matter is composed exert an attractive force on each other in addition to gravity. Although his theory contrasted with that of Ludwig Boltzmann and other contemporaries who adopted a purely kinematical outlook, it is now widely accepted. Indeed, in introducing the idea, modern texts usually refer to the 'Sutherland model' and characterize the force in terms of the 'Sutherland potential'. In his early papers Sutherland supposed that the complete law of force between particles is a power series in 1/r² of which gravity is but the first term; he believed he had uncovered the second, 1/r⁴ term, in his own investigations into the behaviour of matter at the molecular level. (Nowadays this force is usually taken to be 1/r⁷ in form.) Sutherland's general approach enabled him in 1893 to account successfully for one of the more striking difficulties confronting molecular theory at the time, the discrepancy between theory and experiment in regard to the dependence of the viscosity of a gas on its temperature. He showed that the existence of an attractive force between the molecules of the gas would increase the effective diameter of the molecules in the theory that had been worked out for forceless molecules. This research led him to include an extra term C/T in the formula linking viscosity and temperature, T being the absolute temperature and C a constant for any particular gas that is now called Sutherland's Constant. Sutherland later came to regard his new inter-molecular force as quite separate from gravity and attributable to the existence within all ordinary molecules of polarized electric doublets. Working out the consequences of this notion became a major part of his subsequent research.

Sutherland's principal concern was to understand the properties of matter in bulk in terms of its behaviour at the microscopic level. He worked very much on his own, although he enjoyed cordial relations with the few other physicists working in Australia. He wrote for an international audience, attacking such questions as the surface tension of liquids, diffusion, the rigidity of solids, the properties of solutions (including an influential analysis of the structure of water), the origin of spectra and the source of the earth's magnetic field. His ideas were invariably treated with respect, even when they did not win wide acceptance.

While modest and unassuming, Sutherland defended his views vigorously. A widely cultured man with a passion for music as well as science, he liked nothing more than long tramps through the bush. Somewhat shy, but held in deep affection by those who knew him, he never married. He died of a ruptured heart on 5 October 1911 at his family's Kew home and was buried in Melbourne general cemetery.