Trouton, Frederick Thomas

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(b. Dublin, Ireland, 24 November 1863; d. Downe, Kent, England, 21 September 1922)


Trouton came from a wealthy and prominent Dublin family. He performed brilliantly in his undergraduate work at Trinity College, Dublin, taking degrees in both engineering and physical science. In recognition of this work, he was awarded the Large Gold Medal, an honor rarely bestowed for work in science. Trouton remained at Trinity College as FitzGerald’s assistant. Trouton and FitzGerald remained the closest of colleagues and confidants until FitzGerald’s death in 1901. In 1902 Trouton was appointed Quain professor of physics, University College London. At London he pursued his interests in both engineering and physics until 1912, when he was struck by a severe illness that led to permanent paralysis in both legs. Trouton’s active scientific career was at an end, but his spirit was not broken, and the wit and charm for which he was noted were not dampened even after the loss of his two sons in World War I. He continued to advise students and colleagues from his sickbed until his death at the age of fifty-eight.

Throughout his career, Trouton occupied himself with problems in both engineering and physical science. As an undergraduate, he discovered a relationship–known as Trouton’s Law—between the latent heat and the molecular weight of a substance. According to the law, the ratio of the product of the molecular weight and the latent heat to the absolute temperature is a constant. The relationship is not precise and Trouton himself held it to be of little significance. It was also during his undergraduate days that Trouton took an active role in surveying for a railway.

Trouton’s dual interests in applied research and physics continued throughout his career. He devoted considerable energy to investigations of the viscosity of pitch and molten glass at a variety of temperatures; the dynamics of the condensation of water vapor on glass, glass wool, and related substances; the effects of surface moisture on the conductivity of glass; and the relationship between the concentration and the adsorption of dyestuffs on sand. The practical implications of these studies were an explicit motivation for carrying them out.

The influence of FitzGerald seems to have been decisive in Trouton’s more abstract research. Thus, shortly after Hertz published his startling discovery of the propagation of electromagnetic fields, Trouton and FitzGerald undertook a series of replicate investigations. But the investigations for which Trouton is remembered were those in which he attempted to determine the relative velocity of the earth and ether.

Independent of Hendrik A. Lorentz, FitzGerald had suggested that the null result of the Michelson Morley experiment could be accounted for if one assumed that material objects contracted in the direction of motion as a result of interaction with ether. In 1903 Trouton and H. R. Noble undertook an experiment to measure the torsional force on a suspended charged plate condenser as a result of the interaction of the charges in the plates with the ether wind. The widely publicized results were, of course, null.

In 1908, in association with Alexander O. Rankine, Trouton undertook yet another ether drift experiment. They attempted to measure the change in resistance of a copper wire when the wire is rotated parallel and transverse to the direction in which the earth moves around the sun. As was the case with the Trouton-Noble experiment, the experiment was an extremely delicate one, calling for a considerable degree of virtuosity and cleverness. But again the results were null.

Such research placed Trouton in the great tradition. of nineteenth-century British physics. He was, perhaps, the last of the well-trained British ethermechanists.


I. Original Works. Trouton’s published articles include “On Molecular Latent Heat,” in Philosophical Magazine, 18 (1884), 54–57; “Repetition to Hertz’s Experiments and Determination of the Direction of the Vibration of Light,” in Nature, 39 (1889), 391 – 393; “Electrolysis Away From Electrodes, “in Electrician, 43 (1899), 294: ”Flow of Liquid Through Partitions,“ibid., 596 – 597: “Effect on Charged Condenser of Motion through the Ether,” in Transactions of the Royal Dublin Society, 7 (1902), 379 – 384; “Forces Acting on a Charged Condenser Moving Through Space,“with H. R. Noble, in Proceedings of the Royal Society, 72 (1903), 132 – 133; “Forces Acting on a Charged Condenser Moving Through Space,” with H. R. Noble, in Philosophical Transactions of the Royal Society, 202A (1904), 165 – 181; “Viscosity of Pitch-like Substances,” with E. S. Andrews, in Philosophy of the Physical Society, 19 (1904), 47 – 56; “Coefficient of Viscous Traction and Its Relation to That of Viscosity,” in Proceedings of the Royal Society, 77A (1906), 426 – 440: “Vapour Pressure in Equilibrium With Substances Holding Varying Amounts of Moisture, “ibid., 292 – 314; “Leakage Currents on Glass Surfaces,” with C. Searle, in Philosophy Magazine, 12 (1906), 336 – 347; “Condensation of Water Vapour on Glass Surfaces,” in Proceedings of the Royal Society, 79A (1907), 383 – 390; “Condensation of Moisture of Solid Surfaces, “in Chemical News, 96 (1907), 92 – 93; “Rate of Recovery of Residual Charge in Electric Condensers,” with S. Russ, in Phisolophical Magazine, 13 (1907), 578 – 588; “Electrical Resistance in Moving Matter,” in Proceedings of the Royal Society, 80A (1908), 420 – 435; “Mechanism of the Semipermeable Membrane and a New Method of Determining Osmotic Pressure,” ibid., 86A (1912), 149 – 154.

II. Secondary Literature. An obituary may be found in Nature, 110 (1922), 490 – 491. For biographical sketches, see Proceedings of the Royal Society, 110A (1926), iv; and E. Scott Barr, “Anniversaries in 1963,” in American Journal of Physics, 31 (1963), 85 – 86.

Stanley Goldberg