Person: Orr, William McFadden
William McFadden Orr was an Irish mathematician who worked on thermodynamics and fluid flow.
Mathematical Profile (Excerpt):
- Fletcher Orr was a farmer in Ballystockhart who also owned corn and flax mills.
- William attended the local school, Ballystockhart National, where he was taught by Mr R Dickson, before spending two years at Newtownards Intermediate where he was taught by Mr J Boyd.
- Orr thrived under the excellent tuition given by McNeill and he was taught geometry from the textbooks of Richard Townsend (Chapters on the modern geometry of the point, line, and circle), and John Casey.
- Queen's College, Belfast, was one of the colleges of the Royal University of Ireland and it was there that Orr studied.
- At St John's College he was taught by Joseph Larmor and the two became life-long friends with Orr obtaining much advice from his teacher.
- Orr became one of several eminent professors who struggled to keep up their research because of heavy teaching loads.
- We learn something of Orr's problems in his new job from a letter he wrote from Rathgar, Dublin, to Joseph Larmor on 8 October 1895.
- In this letter Orr asks Larmor for information regarding Captain Abney's knowledge of mathematics.
- Captain William de Wiveleslie Abney (1843-1920) was a scientific photographer particularly interested in applications of photography to astronomy.
- Orr tells Larmor that he has a meeting with Abney shortly regarding the syllabus he has to teach at the Royal College of Science, Dublin.
- Orr writes that he considers the subjects he has been asked to teach as being too much, both for himself and for his students.
- Orr's first publications were on hypergeometric series, Fourier double integrals involving Bessel functions which he followed up with a similar paper involving Legendre functions.
- In 1898 Orr published On the forced precession and nutations of a rotating ellipsoidal shell containing liquid in the Philosophical Magazine.
- Orr was not the only one to find errors in Lord Kelvin's paper, for some years later Henri Poincaré also found the errors.
- In 1904 Orr published On Clausius' theorem for irreversible cycles, and on the increase of entropy, published in the Philosophical Magazine.
- In 1906, Orr submitted to the Royal Irish Academy the first of his two papers entitled The Stability or Instability of the Steady Motions of a Perfect Liquid and of a Viscous Liquid, this first part being subtitled A Perfect Liquid.
- Orr is best remembered today by applied mathematicians through the Orr-Sommerfeld equation that is an eigenvalue problem which models 2-dimensional modes of disturbance in a parallel shear flow.
- He was not aware of William McFadden Orr's more extensive work.
- Other mathematicians and physicists also did not take note of Orr's work.
- Even in Great Britain Orr's contribution seems to have been ignored for some years.
- Horace Lamb, the author of the well-known textbook on hydrodynamics, still did not mention Orr's publication in 1910 when Sommerfeld asked him about new publications on turbulence.
- This seems to be the first time when both Orr and Sommerfeld appeared together.
- Orr was elected a fellow of the Royal Society of London in 1909.
- On 11 May 1916, Orr wrote to Larmor about the Easter Uprising in Dublin and its aftermath.
- Orr suggested that the government treated the rebels too leniently and says that most of the Protestants he has spoken to agree with him.
- However, University College Dublin offered the Royal College of Science accommodation and for two years Orr was one of the professors teaching in the University buildings on St Stephen's Green.
- Orr accepted this offer and became a Professor of Pure and Applied Mathematics at University College Dublin.
- James Richard Timoney attended Orr's lectures at University College Dublin in 1928.
- Timoney, known as Dick, worked with Edmund Whittaker in Edinburgh before returning to University College Dublin in 1932 where he became a colleague of Orr.
- In the early 1920s Orr had a lengthy period of inactivity in research.
- In a letter to Larmor on 28 March 1925 he says he has started research again but is worried about his health, both physical and mental, and says he is not sleeping.
- Certainly the late William McFadden Orr possessed both in the highest degree.
Born 2 May 1866, Ballystockhart, Comber, County Down, Ireland. Died 14 August 1934, Douglas, Isle of Man.
View full biography at MacTutor
Tags relevant for this person:
Astronomy, Origin Ireland
Thank you to the contributors under CC BY-SA 4.0! 
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- @J-J-O'Connor
- @E-F-Robertson
References
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive
