seamus dubhghaill

Promoting Irish Culture and History from Little Rock, Arkansas, USA

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Birth of Irish Mathematician James Thomson

James Thomson, Irish mathematician notable for his role in the formation of the thermodynamics school at the University of Glasgow, Is born on November 13, 1786, in Ballynahinch, County Down, in what is now Northern Ireland. He is the father of the engineer and physicist James Thomson and the physicist William Thomson, 1st Baron Kelvin.

Born into an Ulster Scots family, Thomson is the fourth son of Agnes Nesbit and James Thomson, a small farmer, at Annaghmore, near Ballynahinch, County Down, in Ulster. His early education is from his father. At the age of 11 or 12 he finds out for himself the art of dialling. His father sends him to a school at Ballykine, near Ballynahinch, kept by Samuel Edgar, father of John Edgar. Here he soon rises to be an assistant.

Wishing to become a minister of the Presbyterian church, Thomson enters the University of Glasgow in 1810, where he studies for several sessions, supporting himself by teaching in the Ballykine school during the summer. He graduates MA in 1812, and in 1814 he is appointed headmaster of the school of arithmetic, bookkeeping, and geography in the newly established Royal Belfast Academical Institution. In 1815 he is Professor of Mathematics in its collegiate department. Here he proves himself as a teacher. In 1829 the honorary degree of LL.D. is conferred upon him by the University of Glasgow, where in 1832 he is appointed Professor of Mathematics. He holds this post until his death on January 12, 1849.

Thomson is buried with his family on the northern slopes of the Glasgow Necropolis to the east of the main bridge entrance. The grave is notable due to the modern memorial to Lord Kelvin at its side.

Thomson is the author of schoolbooks that have passed through many editions including Arithmetic (1819), Trigonometry, Plane and Spherical (1820), Introduction to Modern Geography (1827), The Phenomena of the Heavens (1827), The Differential and Integral Calculus (1831), and Euclid (1834).

A paper, “Recollections of the Battle of Ballynahinch, by an Eye-witness,” which appears in the Belfast Magazine for February 1825, is from his pen.

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Birth of Mary Ward, Astronomer, Microscopist, Author & Artist

Mary Ward (née King), Irish naturalist, astronomer, microscopist, author, and artist, is born in Ballylin near present-day Ferbane, County Offaly, on April 27, 1827. She is killed in 1869 when she falls under the wheels of an experimental steam car built by her cousins, thereby becoming the first person known to be killed by a motor vehicle.

King is the youngest child of the Reverend Henry King and his wife Harriette. She and her sisters are educated at home, as are most girls at the time. However, her education is slightly different from the norm because she is of a renowned scientific family. She is interested in nature from an early age, and by the time she is three years old she is collecting insects.

King is a keen amateur astronomer, sharing this interest with her cousin, William Parsons, 3rd Earl of Rosse, who builds the Leviathan of Parsonstown, a reflecting telescope with a six-foot mirror which remains the world’s largest until 1917. She is a frequent visitor to Birr Castle, producing sketches of each stage of the process. Along with photographs made by Parson’s wife, Mary Rosse, her sketches are used to aid in the restoration of the telescope.

King also draws insects, and the astronomer James South observes her doing so one day. She is using a magnifying glass to see the tiny details, and her drawing so impresses him that he immediately persuades her father to buy her a microscope. A compound microscope made by Andrew Ross is purchased for £48 12s 8d. This is the beginning of a lifelong passion. She begins to read everything she can find about microscopy, and teaches herself until she has an expert knowledge. She makes her own slides from slivers of ivory, as glass is difficult to obtain, and prepares her own specimens. The physicist David Brewster asks her to make his microscope specimens, and uses her drawings in many of his books and articles.

Universities and most societies do not accept women at the time, but King obtains information any way she can. She writes frequently to scientists, asking them about papers they had published. During 1848, Parsons is made president of the Royal Society, and visits to his London home allows her to meet many scientists.

King is one of only three women on the mailing list for the Royal Astronomical Society. The others are Queen Victoria and Mary Somerville, a scientist for whom Somerville College at the University of Oxford is named.

On December 6, 1854, King marries Henry Ward of Castle Ward, County Down, who in 1881 succeeds to the title of Viscount Bangor. They have three sons and five daughters, including Maxwell Ward, 6th Viscount Bangor. Her best-known descendants are her grandson, Edward Ward, the foreign correspondent and seventh viscount, and his daughter, the Doctor Who actress Lalla Ward.

When Ward writes her first book, Sketches with the microscope (privately printed in 1857), she apparently believes that no one will print it because of her gender or lack of academic credentials. She publishes 250 copies of it privately, and several hundred handbills are distributed to advertise it. The printing sells during the next few weeks, which prompts a London publisher to take the risk and contract for future publication. The book is reprinted eight times between 1858 and 1880 as A World of Wonders Revealed by the Microscope. A new full-colour facsimile edition at €20 is published in September 2019 by the Offaly Historical and Archaeological Society, with accompanying essays.

Her books are A Windfall for the Microscope (1856), A World of Wonders, Revealed by the Microscope (1857), Entomology in Sport, and Entomology in Earnest (1857, with Lady Jane Mahon), Microscope Teachings (1864), Telescope Teachings (1859). She illustrates her books and articles herself, as well as many books and papers by other scientists.

Ward is the first known automobile fatality. William Parsons’ sons had built a steam-powered car and on August 31, 1869, she and her husband are traveling in it with the Parsons boys, Richard Clere Parsons and the future steam turbine pioneer Charles Algernon Parsons, and their tutor, Richard Biggs. She is thrown from the car on a bend in the road at Parsonstown (present-day Birr, County Offaly). She falls under its wheel and dies almost instantly. A doctor who lives near the scene arrives within moments, and finds her cut, bruised, and bleeding from the ears. The fatal injury is a broken neck. It is believed that the grieving family destroys the car after the crash.

Ward’s microscope, accessories, slides and books are on display in her husband’s home, Castle Ward, County Down. William Parsons’ home at Birr Castle, County Offaly, is also open to the public.


Death of John Hewitt Jellett, Mathematician & Priest

John Hewitt Jellett, Irish mathematician whose career is spent at Trinity College Dublin (TCD), where he rises to the rank of Provost, dies in Dublin on February 19, 1888. He is also a priest in the Church of Ireland.

Jellett is born at Cashel, County Tipperary, on December 25, 1817, the son of Rev. Morgan Jellett and his wife Harriette Townsend, daughter of Hewitt Baldwin Poole of County Cork, by his wife Dorothea Morris. He is the eldest brother of Hewitt Poole Jellett, Serjeant-at-law (Ireland) and Chairman of the Quarter Sessions for County Laois, and of the Venerable Henry Jellett, Archdeacon of Cloyne. He is educated at Kilkenny College and at TCD, where he becomes a fellow in 1840.

Jellett marries his cousin on his mother’s side, Dorothea Charlotte Morris Morgan, daughter of James Morgan, on July 7, 1855. The marriage produces seven children. His son, William Morgan Jellett, is a member of the Parliament of the United Kingdom and is the father of the celebrated artist Mainie Jellett, and of Dorothea Jellett, director of the orchestra of the Gaiety Theatre, Dublin. Another son Henry Holmes Jellett is a civil engineer in British India. His daughter Harriette Mary Jellett is the wife of the noted Irish physicist George Francis FitzGerald. Another daughter Eva Jellett is the first woman to graduate with a degree in medicine from Trinity, and goes on to practice as a doctor in India.

Jellett graduates B.A. in mathematics in 1837, M.A. 1843, B.D. 1866, and D.D. 1881. He is ordained a priest in 1846. In 1848 he is elected to the chair of natural philosophy at TCD, and in 1868 he receives the appointment of commissioner of Irish national education.

In 1851 Jellett is awarded the Cunningham Medal of the Royal Irish Academy for his work on the “Calculus of Variations.” The society later elects him their president, a position he holds from 1869 to 1874.

In 1870, on the death of Dr. Thomas Luby, Jellett is co-opted a Senior Fellow, and thus a member of the Board of TCD. William Ewart Gladstone‘s government in February 1881 appoints him provost of Trinity. In the same year he is awarded a Royal Medal by the Royal Society.

After the disestablishment of the Church of Ireland by the Irish Church Act 1869, Jellett takes an active part in the deliberations of the general synod and in every work calculated to advance its interests. He is an able mathematician, and writes A Treatise of the Calculus of Variations (1850), and A Treatise on the Theory of Friction (1872), as well as several papers on pure and applied mathematics, articles in the Transactions of the Royal Irish Academy. He also writes some theological essays, sermons, and religious treatises, of which the principal are An Examination of some of the Moral Difficulties of the Old Testament (1867), and The Efficacy of Prayer (1878).

Jellett dies of blood poisoning at the provost’s house, TCD, on February 19, 1888, and is buried in Mount Jerome Cemetery on February 23. The funeral procession is the largest that ever left Trinity.

(Pictured: “John Hewitt Jellett,” oil on canvas by Sarah Purser)

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Death of Mathematician Sir William Rowan Hamilton

Sir William Rowan Hamilton, Irish mathematician, Andrews Professor of Astronomy at Trinity College, Dublin, and Royal Astronomer of Ireland, who makes important contributions to classical mechanics, optics, and algebra, dies in Dublin on September 2, 1865, following a severe attack of gout.

Hamilton is born in Dublin on August 4, 1805, the fourth of nine children born to Sarah Hutton (1780–1817) and Archibald Hamilton (1778–1819). He is part of a small but well-regarded school of mathematicians associated with Trinity College, Dublin, which he enters at age eighteen. He is said to have shown immense talent at a very early age. Astronomer Bishop Dr. John Brinkley remarks of the 18-year-old Hamilton, “This young man, I do not say will be, but is, the first mathematician of his age.”

Trinity College awards him two Optimes, or off-the-chart grades. He studies both classics and mathematics, and is appointed Professor of Astronomy just prior to his graduation. He then takes up residence at Dunsink Observatory where he spends the rest of his life.

Although Hamilton regards himself as a pure mathematician rather than a physicist, his work is of major importance to physics, particularly his reformulation of Newtonian mechanics, now called Hamiltonian mechanics. This work has proven central to the modern study of classical field theories such as electromagnetism, and to the development of quantum mechanics. In pure mathematics, he is best known as the inventor of quaternions.

Hamilton’s scientific career includes the study of geometrical optics, classical mechanics, adaptation of dynamic methods in optical systems, applying quaternion and vector methods to problems in mechanics and in geometry, development of theories of conjugate algebraic couple functions, solvability of polynomial equations and general quintic polynomial solvable by radicals, the analysis on Fluctuating Functions, linear operators on quaternions and proving a result for linear operators on the space of quaternions, which is a special case of the general theorem which today is known as the Cayley–Hamilton theorem. He also invents Icosian calculus, which he uses to investigate closed edge paths on a dodecahedron that visit each vertex exactly once.

Hamilton retains his faculties unimpaired to the very last, and steadily continues the task of finishing the Elements of Quaternions which occupies the last six years of his life. He dies in Dublin on September 2, 1865, following a severe attack of gout precipitated by excessive drinking and overeating. He is buried in Mount Jerome Cemetery in Dublin.

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Birth of George Francis FitzGerald, Academic & Physicist

Professor George Francis FitzGerald FRS FRSE, Irish academic and physicist, is born at No. 19, Lower Mount Street in Dublin on August 3, 1851. He is known for his work in electromagnetic theory and for the Lorentz–FitzGerald contraction, which becomes an integral part of Albert Einstein‘s special theory of relativity.

FitzGerald is born to the Reverend William FitzGerald and his wife Anne Frances Stoney. He is the nephew of George Johnstone Stoney, the Irish physicist who coins the term “electron.” After the particles are discovered by J. J. Thomson and Walter Kaufmann in 1896, FitzGerald is the one to propose calling them electrons. He is also the nephew of Bindon Blood Stoney, an eminent Irish engineer. His cousin is Edith Anne Stoney, a pioneer female medical physicist.

Professor of Moral Philosophy at Trinity College Dublin and vicar of St. Anne’s, Dawson Street, at the time of his son’s birth, William FitzGerald is consecrated Bishop of Cork, Cloyne and Ross in 1857 and translates to Killaloe and Clonfert in 1862. George returns to Dublin and enters TCD as a student at the age of sixteen, winning a scholarship in 1870 and graduating in 1871 in Mathematics and Experimental Science. He becomes a Fellow of Trinity in 1877 and spends the rest of his career there, serving as Erasmus Smith’s Professor of Natural and Experimental Philosophy from 1881 to 1901.

Along with Oliver Lodge, Oliver Heaviside and Heinrich Hertz, FitzGerald is a leading figure among the group of “Maxwellians” who revise, extend, clarify, and confirm James Clerk Maxwell‘s mathematical theories of the electromagnetic field during the late 1870s and the 1880s.

In 1883, following from Maxwell’s equations, FitzGerald is the first to suggest a device for producing rapidly oscillating electric currents to generate electromagnetic waves, a phenomenon which is first shown to exist experimentally by the German physicist Heinrich Hertz in 1888.

In 1883, FitzGerald is elected Fellow of the Royal Society. In 1899, he is awarded a Royal Medal for his investigations in theoretical physics. In 1900, he is made an honorary fellow of the Royal Society of Edinburgh.

FitzGerald is better known for his conjecture in his short letter to the editor of Science. “The Ether and the Earth’s Atmosphere” explains that if all moving objects were foreshortened in the direction of their motion, it would account for the curious null-results of the Michelson–Morley experiment. He bases this idea in part on the way electromagnetic forces are known to be affected by motion. In particular, he uses some equations that had been derived a short time before by his friend the electrical engineer Oliver Heaviside. The Dutch physicist Hendrik Lorentz hits on a very similar idea in 1892 and develops it more fully into Lorentz transformations, in connection with his theory of electrons.

The Lorentz–FitzGerald contraction hypothesis becomes an essential part of the Special Theory of Relativity, as Albert Einstein publishes it in 1905. He demonstrates the kinematic nature of this effect, by deriving it from the principle of relativity and the constancy of the speed of light.

FitzGerald suffers from many digestive problems for much of his shortened life. He becomes very ill with stomach problems. He dies on February 22, 1901 at his home, 7 Ely Place in Dublin, the day after an operation on a perforated ulcer. He is buried in Mount Jerome Cemetery.

A crater on the far side of the Moon is named after FitzGerald, as is a building at Trinity College Dublin.

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Birth of Sir Joseph Larmor, Physicist & Mathematician

Sir Joseph Larmor FRS FRSE, Irish and British physicist and mathematician who makes breakthroughs in the understanding of electricity, dynamics, thermodynamics, and the electron theory of matter, is born in Magheragall, County Antrim on July 11, 1857. His most influential work is Aether and Matter, a theoretical physics book published in 1900.

Larmor is the son of Hugh Larmor, a Belfast shopkeeper and his wife, Anna Wright. The family moves to Belfast around 1860, and he is educated at the Royal Belfast Academical Institution, and then studies mathematics and experimental science at Queen’s College, Belfast, where one of his teachers is John Purser. He obtains his BA in 1874 and MA in 1875. He subsequently studies at St. John’s College, Cambridge where in 1880 he is Senior Wrangler and Smith’s Prizeman, and obtains his MA in 1883. After teaching physics for a few years at Queen’s College, Galway, he accepts a lectureship in mathematics at Cambridge in 1885. In 1892 he is elected a Fellow of the Royal Society of London, and he serves as one of the Secretaries of the society. He is made an Honorary Fellow of the Royal Society of Edinburgh in 1910.

In 1903 Larmor is appointed Lucasian Professor of Mathematics at Cambridge, a post he retains until his retirement in 1932. He never marries. He is knighted by King Edward VII in 1909.

Motivated by his strong opposition to Home Rule for Ireland, in February 1911 Larmor runs for and is elected as Member of Parliament for Cambridge University (UK Parliament constituency) with the Conservative Party. He remains in parliament until the 1922 general election, at which point the Irish question has been settled. Upon his retirement from Cambridge in 1932 he moves back to County Down in Northern Ireland.

Larmor receives the honorary Doctor of Laws (LLD) from the University of Glasgow in June 1901. He is awarded the Poncelet Prize for 1918 by the French Academy of Sciences. He is a Plenary Speaker in 1920 at the International Congress of Mathematicians (ICM) at Strasbourg and an Invited Speaker at the ICM in 1924 in Toronto and at the ICM in 1928 in Bologna.

Larmor dies in Holywood, County Down, Northern Ireland on May 19, 1942.

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Birth of Robert Boyle, Philosopher, Writer & Chemist

Robert Boyle, Anglo-Irish natural philosopher, theological writer, chemist, physicist, inventor and a preeminent figure of 17th-century intellectual culture, is born on January 25, 1627 at Lismore Castle, in County Waterford.

At age eight, Boyle begins his formal education at Eton College, where his studious nature quickly becomes apparent. In 1639 he and his brother Francis embark on a grand tour of the continent together with their tutor Isaac Marcombes. In 1642, owing to the Irish rebellion, Francis returns home while Robert remains with his tutor in Geneva and pursues further studies.

Boyle returns to England in 1644, where he takes up residence at his hereditary estate of Stalbridge in Dorset. There he begins a literary career writing ethical and devotional tracts, some of which employ stylistic and rhetorical models drawn from French popular literature, especially romance writings. In 1649 he begins investigating nature via scientific experimentation. From 1647 until the mid-1650s, he remains in close contact with a group of natural philosophers and social reformers gathered around the intelligencer Samuel Hartlib. This group, the Hartlib Circle, includes several chemists who heighten his interest in experimental chemistry.

Boyle spends much of 1652–1654 in Ireland overseeing his hereditary lands and performing some anatomic dissections. In 1654 he is invited to Oxford, and he takes up residence at the university until 1668. In Oxford he is exposed to the latest developments in natural philosophy and becomes associated with a group of notable natural philosophers and physicians, including John Wilkins, Christopher Wren, and John Locke. These individuals, together with a few others, form the “Experimental Philosophy Club.” Much of Boyle’s best known work dates from this period.

In 1659 Boyle and Robert Hooke, the clever inventor and subsequent curator of experiments for the Royal Society, complete the construction of their famous air pump and use it to study pneumatics. Their resultant discoveries regarding air pressure and the vacuum appear in Boyle’s first scientific publication, New Experiments Physico-Mechanicall, Touching the Spring of the Air and Its Effects (1660). Boyle and Hooke discover several physical characteristics of air, including its role in combustion, respiration, and the transmission of sound. One of their findings, published in 1662, later becomes known as “Boyle’s law.” This law expresses the inverse relationship that exists between the pressure and volume of a gas, and it is determined by measuring the volume occupied by a constant quantity of air when compressed by differing weights of mercury.

Among Boyle’s most influential writings are The Sceptical Chymist (1661), which assails the then-current Aristotelian and especially Paracelsian notions about the composition of matter and methods of chemical analysis, and the Origine of Formes and Qualities (1666), which uses chemical phenomena to support the corpuscularian hypothesis. He argues so strongly for the need of applying the principles and methods of chemistry to the study of the natural world and to medicine that he later gains the appellation of the “father of chemistry.”

Boyle is a devout and pious Anglican who keenly champions his faith. He sponsors educational and missionary activities and writes a number of theological treatises. He is deeply concerned about the widespread perception that irreligion and atheism are on the rise, and he strives to demonstrate ways in which science and religion are mutually supportive. For Boyle, studying nature as a product of God’s handiwork is an inherently religious duty. He argues that this method of study would, in return, illuminate God’s omnipresence and goodness, thereby enhancing a scientist’s understanding of the divine. The Christian Virtuoso (1690) summarizes these views and may be seen as a manifesto of his own life as the model of a Christian scientist.

In 1668 Boyle leaves Oxford and takes up residence with his sister Katherine Jones, Vicountess Ranelagh, in her house on Pall Mall in London. There he sets up an active laboratory, employs assistants, receives visitors, and publishes at least one book nearly every year. Living in London also provides him the opportunity to participate actively in the Royal Society.

Boyle is a genial man who achieves both national and international renown during his lifetime. He is offered the presidency of the Royal Society and the episcopacy but declines both. Throughout his adult life, he is sickly, suffering from weak eyes and hands, recurring illnesses, and one or more strokes. He dies in London at age 64 on December 31, 1691 after a short illness exacerbated by his grief over Katherine’s death a week earlier. He leaves his papers to the Royal Society and a bequest for establishing a series of lectures in defense of Christianity. These lectures, now known as the Boyle Lectures, continue to this day.

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Birth of John Tyndall, Experimental Physicist

File source: // Tyndall, Irish experimental physicist who, during his long residence in England, is an avid promoter of science in the Victorian era, is born on August 2, 1820 in Leighlinbridge, County Carlow.

Tyndall is born into a poor Protestant Irish family. After a thorough basic education he works as a surveyor in Ireland and England from 1839 to 1847. When his ambitions turns from engineering to science, he spends his savings on gaining a Ph.D. from the University of Marburg in Marburg, Hesse, Germany (1848–1850), but then struggles to find employment.

In 1853 Tyndall is appointed Professor of Natural Philosophy at the Royal Institution, London. There he becomes a friend of the much-admired physicist and chemist Michael Faraday, entertains and instructs fashionable audiences with brilliant lecture demonstrations rivaling the biologist Thomas Henry Huxley in his popular reputation and pursuing his research.

An outstanding experimenter, particularly in atmospheric physics, Tyndall examines the transmission of both radiant heat and light through various gases and vapours. He discovers that water vapor and carbon dioxide absorb much more radiant heat than the gases of the atmosphere and argues the consequent importance of those gases in moderating Earth’s climate, that is, in the natural greenhouse effect. He also studies the diffusion of light by large molecules and dust, known as the Tyndall effect, and he performs experiments demonstrating that the sky’s blue color results from the scattering of the Sun’s rays by molecules in the atmosphere.

Tyndall is passionate and sensitive, quick to feel personal slights and to defend underdogs. Physically tough, he is a daring mountaineer. His greatest fame comes from his activities as an advocate and interpreter of science. In collaboration with his scientific friends in the small, private X Club, he urges greater recognition of both the intellectual authority and practical benefits of science.

Tyndall is accused of materialism and atheism after his presidential address at the 1874 meeting of the British Association for the Advancement of Science, when he claims that cosmological theory belongs to science rather than theology and that matter has the power within itself to produce life. In the ensuing notoriety over this “Belfast Address,” his allusions to the limitations of science and to mysteries beyond human understanding are overlooked. He engages in a number of other controversies such as spontaneous generation, the efficacy of prayer and Home Rule for Ireland.

In his last years Tyndall often takes chloral hydrate to treat his insomnia. When bedridden and ailing, he dies from an accidental overdose of this drug on December 4, 1893 at the age of 73 and was buried at Haslemere, Surrey, England.

Tyndall is commemorated by a memorial, the Tyndalldenkmal, erected at an elevation of 7,680 ft. on the mountain slopes above the village of Belalp, where he had his holiday home, and in sight of the Aletsch Glacier, which he had studied.

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Birth of James Thomson, Engineer & Physicist


James Thomson, engineer and physicist whose reputation is substantial though overshadowed by that of his younger brother William Thomson (Lord Kelvin), is born in Belfast on February 16, 1822.

Thomson spends much of his youth in Glasgow. His father James is professor of mathematics at the University of Glasgow from 1832 onward. He attends Glasgow University from a young age and graduates in 1839 with high honors in his late teens. After graduation, he serves brief apprenticeships with practical engineers in several domains. He then gives a considerable amount of his time to theoretical and mathematical engineering studies, often in collaboration with his brother, during his twenties in Glasgow. In his late twenties he enters into private practice as a professional engineer with special expertise in water transport. In 1855, he is appointed professor of civil engineering at Queen’s University Belfast. He remains there until 1873, when he accepts the Regius professorship of Civil Engineering and Mechanics at the University of Glasgow in which he is successor to the influential William Rankine. He serves in this position until he resigns with failing eyesight in 1889.

In 1875 Thomson is elected a Fellow of the Royal Society of Edinburgh. His proposers are his younger brother William, Peter Guthrie Tait, Alexander Crum Brown and John Hutton Balfour. He is elected a Fellow of the Royal Society of London in June 1877. He serves as President of the Institution of Engineers and Shipbuilders in Scotland from 1884 to 1886.

Thomson dies of cholera in Glasgow on May 8, 1892. He is buried on the northern slopes of the Glasgow Necropolis overlooking Glasgow Cathedral. One obituary describes Thomson as “a man of singular purity of mind and simplicity of character,” whose “gentle kindness and unfailing courtesy will be long remembered.”

Thomson is known for his work on the improvement of water wheels, water pumps and turbines. He is also known for his innovations in the analysis of regelation, i.e., the effect of pressure on the freezing point of water, and his studies in glaciology including glacial motion, where he extends the work of James David Forbes. He studies the experimental work of his colleague Thomas Andrews concerning the continuity of the liquid and gaseous states of matter, and strengthens understanding of it by applying his strong knowledge of thermodynamics. He derives a simplified form of the Clapeyron equation for the solid-liquid phase boundary. He proposes the term triple point to describe the conditions for which solid, liquid and vapour states are all in equilibrium.

Thomson also makes contributions in the realm of fluid dynamics of rivers. It is claimed that the term torque is introduced into English scientific literature by Thomson in 1884.

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Birth of Henry Dixon, Biologist & Professor

Generated by IIPImageHenry Horatio Dixon, plant biologist and professor at Trinity College, Dublin, is born in Dublin on May 19, 1869. Along with John Joly, he puts forward the cohesion-tension theory of water and mineral movement in plants.

Dixon is the youngest of the seven sons of George Dixon, a soap manufacturer, and Rebecca (née Yeates) Dixon. He is educated at Rathmines School and Trinity College, Dublin. In 1894, after studying in Bonn, Germany, he is appointed assistant and later full Professor of Botany at Trinity. In 1906 he becomes Director of the Botanic gardens and in 1910 of the Herbarium also. He has a close working relationship with physicist John Joly and together they develop the cohesion theory of the ascent of sap.

Dixon’s early research includes work on the cytology of chromosomes and first mitosis in certain plants. Familiarity with work on transpiration and on the tensile strength of columns of sulfuric acid and water leads Dixon and Joly to experiment on transpiration. “On the Ascent of Sap” (1894) presents the hypothesis that the sap or water in the vessels of a woody plant ascends by virtue of its power of resisting tensile stress and its capacity to remain cohesive under the stress of great differences of pressure. Dixon and Joly further demonstrate that water is transported through passive vessels and not living cells.

Dixon writes Transpiration and the Ascent of Sap in Plants (1914), which brings various theories and experimental works together in a coherent argument. He also writes a textbook, Practical Plant Biology (1922).

In 1907 Dixon marries Dorothea Mary, daughter of Sir John H. Franks, with whom he raises three sons. He is the father of biochemist Hal Dixon and grandfather of Adrian Dixon and Joly Dixon.

In 1908 Dixon is elected a Fellow of the Royal Society. In 1916 he is awarded the Boyle Medal of the Royal Dublin Society. He delivers the society’s Croonian Lecture in 1937.

Henry Dixon dies in Dublin on December 20, 1953.

(Pictured: Henry Horatio Dixon, bromide print by Walter Stoneman, 1922, National Portrait Gallery, London)