Frederick Thomas Trouton FRS (; 24 November 1863 – 21 September 1922) was an Irish

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

known for Trouton's rule and experiments to detect the Earth's motion through the

luminiferous aether Luminiferous aether or ether ("luminiferous", meaning "light-bearing") was the postulated medium for the propagation of light. It was invoked to explain the ability of the apparently wave-based light to propagate through empty space (a vacuum), s ...

Life and work

Trouton was born in

Dublin Dublin (; , or ) is the capital and largest city of Ireland. On a bay at the mouth of the River Liffey, it is in the province of Leinster, bordered on the south by the Dublin Mountains, a part of the Wicklow Mountains range. At the 2016 cen ...

on 24 November 1863, the youngest son of the wealthy and prominent Thomas Trouton. He attended

Royal School Dungannon The Royal School is a mixed boarding school located in Dungannon, County Tyrone, Northern Ireland. It was one of a number of 'free schools' created by James I (otherwise known as James VI of Scotland) in 1608 to provide an education to the son ...

and went on to

Trinity College, Dublin , name_Latin = Collegium Sanctae et Individuae Trinitatis Reginae Elizabethae juxta Dublin , motto = ''Perpetuis futuris temporibus duraturam'' (Latin) , motto_lang = la , motto_English = It will last i ...

in 1884, where he studied engineering and physical science. While still an undergraduate student, Trouton observed a relationship between

boiling points The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding envir ...

and energies of vaporisations, which he presented in two short papers. He found the change of entropy per mole for vaporisation at a boiling point is constant, or expressed mathematically ΔS_m,vap = 10.5 R (where R is the

ideal gas constant The molar gas constant (also known as the gas constant, universal gas constant, or ideal gas constant) is denoted by the symbol or . It is the molar equivalent to the Boltzmann constant, expressed in units of energy per temperature increment per ...

). This became known as Trouton's rule and, despite having some exceptions, is used to estimate the

enthalpy Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant ...

of vaporisation of liquids whose boiling points are known. Trouton himself belittled his discovery as it was merely the result of an afternoon's manipulation of data from a book of tables. Before graduating he also took a leading role in

surveying Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is ...

for a railway. Trouton graduated Master of Arts and

Doctor of Science Doctor of Science ( la, links=no, Scientiae Doctor), usually abbreviated Sc.D., D.Sc., S.D., or D.S., is an academic research degree awarded in a number of countries throughout the world. In some countries, "Doctor of Science" is the degree used f ...

in 1884, and was immediately appointed assistant to the professor of experimental physics,

George Francis FitzGerald Prof George Francis FitzGerald (3 August 1851 – 22 February 1901) was an Irish academic and physicist who served as Erasmus Smith's Professor of Natural and Experimental Philosophy at Trinity College Dublin (TCD) from 1881 to 1901. FitzGe ...

. They collaborated on many experiments and became good friends; FitzGerald's influence can be seen in much of Trouton's early work. Trouton was elected a

Fellow of the Royal Society Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the judges of the Royal Society of London to individuals who have made a "substantial contribution to the improvement of natural knowledge, including mathemati ...

in June 1897. His application citation read: "''Discovered the law connecting the latent heat of vaporisation and molecular weights of bodies known as "Trouton's law" and experimentally determined the directions of vibration of electric and inaquatic force in plane polarised light. He has made other important observations on the phase of secondary waves and on the influence of the size of the reflector in Hertz's equipment''." A 1902 appointment as Quain Professor of Physics at

University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = � ...

led to a 12-year career of experimental physics, including work on the Trouton-Rankine experiment. He received an

OBE The Most Excellent Order of the British Empire is a British order of chivalry, rewarding contributions to the arts and sciences, work with charitable and welfare organisations, and public service outside the civil service. It was established ...

in 1918. Trouton married Anne Maria Fowler in 1887 and they had four sons and three daughters. Their first two sons, Eric and Desmond, were killed in World War I. He became severely ill in 1912 and an operation in 1914 left him paralysed in the lower limbs and caused his retirement. Despite this, he retained the wit and charm he was known for. After retiring, Trouton lived in

Tilford Tilford is a village and civil parish centred at the point where the two branches of the River Wey merge in Surrey, England, south-east of Farnham. It has half of Charleshill, Elstead in its east, a steep northern outcrop of the Greensand R ...

, Surrey, and then

Downe Downe, formerly Down, () is a village in Greater London, England, located within the London Borough of Bromley but beyond the London urban sprawl. Downe is south west of Orpington and south east of Charing Cross. Downe lies on a hill, and m ...

in Kent where he died on 21 September 1922.

References

{{DEFAULTSORT:Trouton, Frederick Thomas Irish physicists 1863 births 1922 deaths Alumni of Trinity College Dublin Scientists from Dublin (city) People educated at the Royal School Dungannon Fellows of the Royal Society Academics of University College London