features Fluids, Fluorescence and a Hat Full of Beetles Mark McCartney, University of Ulster George is so fond of lightning. ... He puts his head things’ [1, p. 35]. Or he could be found on holiday on the north under all the waterspouts he can find. ... He flew coast of Ireland, in the sea, trouser legs rolled up, checking if the about, now up, now down, trying to find a better path; maximum angle of wave crests agreed with his calculations. On he quite enjoys dangerous places and looks so happy one occasion as a young man, he had to apologise for not bowing when his neck might be broken. [1, p. 16] to a group of ladies in a Cambridge street because his hat was full of beetles. It seems virtually all aspects of the natural world held t first glance these read as a parent’s indulgent de- a fascination for him. scriptions of a playful and inquisitive child. But they are A not. They are taken from the journal of George Gabriel Stokes’ wife, and are all the more remarkable because they were Early life written on honeymoon. They give a hint of Stokes’ omnivorous George Gabriel Stokes was born on 13 August 1819 into a fam- and lifelong curiosity. ily with a habit of producing Church of Ireland clerics and aca- Similarly, with respect to lightning, his daughter said: demics. His father was rector of Skreen parish church, which ‘He would go any distance to see houses and trees that had was a couple of kilometres from the Atlantic Ocean in County been struck’ [1, p. 32]. Despite his apparent lifelong inter- Sligo. He was the youngest of eight children, two of whom died est in thunderstorms, Lord Kelvin, in his obituary of Stokes, in infancy. His three brothers all entered the church. His early stated that electricity was virtually the only area of natural education was at home and overseen by the parish clerk. In 1832, philosophy to which he did not make a significant contri- aged 13, he was sent to Dublin to live with his uncle and attend bution [3]. The term natural philosophy translates to what school there. Then in 1835, he moved to Bristol College. His we today call physics, and in the 19th century for people mathematical ability was commented on in Skreen, Dublin and such as G.G. Stokes, Lord Kelvin and James Clerk Maxwell Bristol, with his sister Elizabeth claiming that: ‘There is a tradi- that meant being engaged both experimentally and theoreti- tion that he did many of the propositions of Euclid as problems, cally, with the mathematics being driven by the need to solve without having looked at the book’ [1, p. 5]. physical problems. Figure 2: Stokes’ birthplace: Skreen Rectory, Co Sligo, as it appeared at the beginning of the 20th century [2] Cambridge In 1837, Stokes entered Pembroke College, Cambridge. As was typical for any student who wanted to appear high on the exam- ination lists, he studied under a private tutor. The tutor, William Hopkins, had an eye for strong students and a reputation for con- Science Photo Library verting their strength into becoming Senior Wrangler (i.e. obtain- ing the highest marks in the Mathematical Tripos examinations). Figure 1: George Gabriel Stokes (1819–1903) A significant number of major figures in 19th century mathe- matics and natural philosophy passed through Hopkins’ hands, While today Stokes is remembered by undergraduates be- including J.J. Sylvester, Arthur Cayley, William Thomson (later cause his name is attached to mathematical results such as the Lord Kelvin), E.J. Routh, P.G. Tait and James Clerk Maxwell. Navier–Stokes equation and Stokes’ theorem (see box), in his In 1841, Stokes’ studies paid off and he was announced as Se- lifetime he could also be found in his home in Cambridge ex- nior Wrangler, and shortly afterwards also took first place in the perimenting on fluorescence with ‘strange infusions which smelt Smith’s Prize examinations. Such a strong performance meant horribly, horse-chestnut bark and leaves and all sorts of other that a fellowship at Pembroke inevitably followed. Mathematics TODAY AUGUST 2019 142 StokesStokesStokes went went went on, on, on, in in inOctober October October 1849, 1849, 1849, to to tobe be be elected elected elected the the the 13th 13th 13thFromFromFrom that that that suggestion suggestion suggestion flowed flowed flowed over over over 20 20 20 papers, papers, papers, clustered clustered clustered at at the at the the be- be- be- LucasianLucasianLucasian Professor Professor Professor of of Mathematics.of Mathematics. Mathematics. P.G. P.G. P.G. Tait, Tait, Tait, a a student astudent student at at Cam- at Cam- Cam-ginningginningginning and and and end end end of of hisof his his life life life (1842–50 (1842–50 (1842–50 and and and 1880–98), 1880–98), 1880–98), covering covering covering the the the bridgebridgebridge at at the at the the time, time, time, declared declared declared that that that he he heand and and his his his fellow fellow fellow undergraduates undergraduates undergraduatesnaturenaturenature of of fluidof fluid fluid flow flow flow and and and the the the theory theory theory of of waterof water water waves. waves. waves. Interestingly Interestingly Interestingly hadhadhad not not not even even even heard heard heard of of ofStokes Stokes Stokes before before before his his his appointment. appointment. appointment. The The The sug- sug- sug-thethethe work work work he he he considered considered considered his his his most most most important important important in in thein the the area area area of of offluids fluids fluids gestiongestiongestion that that that Stokes Stokes Stokes was was was a a relative arelative relative unknown unknown unknown is is backed is backed backed up up up by by by the the thewaswaswas an an an1851 1851 1851 paper, paper, paper, ‘On ‘On ‘On the the the effect effect effect of of internalof internal internal friction friction friction of of fluidsof fluids fluids on on on factfactfact that that thatTheTheThe Times Times Timesandandand two two two Cambridge Cambridge Cambridge papers papers papers erroneously erroneously erroneously an- an- an-thethethe motion motion motion of of pendulums’of pendulums’ pendulums’ [5, [5, [5, pp. pp. pp. 1–141] 1–141] 1–141] (see (see (see box). box). box). Certainly Certainly Certainly an an an nouncednouncednounced that that that it it was it was was Stokes’ Stokes’ Stokes’ elder elder elder brother, brother, brother, Reverend Reverend Reverend W.H. W.H. W.H. Stokes, Stokes, Stokes,accurateaccurateaccurate understanding understanding understanding of of pendulaof pendula pendula for for for timekeeping timekeeping timekeeping and and and geodesy geodesy geodesy SeniorSeniorSenior Fellow Fellow Fellow of of ofCaius, Caius, Caius, who who who had had had been been been appointed. appointed. appointed. Stokes Stokes Stokes was was waswaswaswas important important important in in thein the the 19th 19th 19th century, century, century, but but but it it is it is not is not not the the the paper paper paper where where where amusedamusedamused rather rather rather than than than piqued piqued piqued by by bythe the the error. error. error. hehehe writes writes writes down down down what what what we we we now now now call call call the the the Navier–Stokes Navier–Stokes Navier–Stokes equation. equation. equation. TodayTodayToday the the the Lucasian Lucasian Lucasian Chair Chair Chair is is seen is seen seen as as aas a stellar stellara stellar appointment, appointment, appointment, as- as- as-ThisThisThis appeared appeared appeared in in 1845 in 1845 1845 in in ‘On in ‘On ‘On the the the theories theories theories of of theof the the internal internal internal friction friction friction sociatingsociatingsociating the the the incumbent incumbent incumbent with with with previous previous previous holders holders holders such such such as as asNewton, Newton, Newton,ofofof fluids fluids fluids in in motion,in motion, motion, and and and of of ofthe the the equilibrium equilibrium equilibrium and and and motion motion motion of of ofelas- elas- elas- Dirac,Dirac,Dirac, Hawking Hawking Hawking and and and Stokes Stokes Stokes himself. himself. himself. However, However, However, it it was it was was not not not quite quite quitetictictic solids’ solids’ solids’ [4, [4, [4, pp. pp. pp. 75–129]. 75–129]. 75–129]. Stokes Stokes Stokes was was was not not not the the the first first first to to write to write write the the the seenseenseen that that that way way way in in his in his his day. day. day. A A Lucasian A Lucasian Lucasian Professor Professor Professor from from from 20 20 20 years years years be- be- be-equationequationequation down. down. down. Claude-Louis Claude-Louis Claude-Louis Navier Navier Navier had had had done done done so so inso in 1822, in 1822, 1822, and and and in in in foreforefore Stokes, Stokes, Stokes, George George George Biddell Biddell Biddell Airy, Airy, Airy, complained complained complained that that that he he hehad had had to to take to take takebetweenbetweenbetween then then then and and and 1845 1845 1845 so so hadso had had Cauchy, Cauchy, Cauchy, Poisson Poisson Poisson and and and Saint-Venant. Saint-Venant. Saint-Venant. aa one-thirda one-third one-third cut cut cut in in payin pay pay to to taketo take take the the the role, role, role, and and and matching matching matching his his his action action actionStokesStokesStokes notes notes notes that that that on on on finishing finishing finishing the the the paper paper paper [4, [4, [4, p.77]: p.77]: p.77]: toto histo his his complaint complaint complaint stayed stayed stayed in in the in the the job job job for for for scarcely scarcely scarcely more more more than than than a a year.