Died: 10 October 1925 in Glasgow, Scotland

Andrew Gray's parents were Margaret Wilson and John Gray, who was a farmer at Lochgelly. Gray attended the Subscription School in Lochgelly where the practical nature of mathematics was stressed in a rather unusual way. His schoolmaster [2]:-

... showed them how to measure the distance of conspicuous objects out of doors by means of a measured baseline. In this way Gray, when a boy, measured the distance of Nelson's monument on the Calton Hill, the lighthouse on the island of Inchkeith, the Martello tower at Leith Harbour, North Berwick Law, and other objects that can be seen from Burntisland. The practical nature of the teaching intensely interested the boys. In later life Gray always tried to make sure the problems he set the students as practical and as humanly interesting as possible.

Gray then received private tuition in Edinburgh before entering the University of Glasgow in 1872. Notice that he was 25 years of age before beginning his university studies. He graduated M.A. in 1876, with First Class Honours in Mathematics and Natural Philosophy. His undergraduate years had been highly successful ones and he won prizes in natural philosophy in session 1874-5, and in mathematics in session 1875-6. However he had a hard time as a student for he was required to help with the farm back in Lochgelly and had to leave his studies at certain points to do so [2]:-

Gray ever put duty before personal ambition, and did not seem to mind.

In 1874, while he was still an undergraduate, Gray was appointed private assistant and secretary to Sir William Thomson (later Lord Kelvin), who was Professor of Natural Philosophy at Glasgow. In 1880 he became Kelvin's official assistant [2]:-

Gray took a leading part in the testing of dynamos ... and in the testing of accumulators and of electric lamps.

Gray assisted by marking the examination papers for Kelvin's Senior Honours Natural Philosophy class. When the scripts were returned to the students they discovered [2]:-

... that not only had he written out the solutions of those questions which had been answered incorrectly, but he had also written out complete solutions of all those which he had not attempted.

In 1884 Gray became the foundation professor of physics in the University College of North Wales, Bangor [2]:-

While in Wales, he championed the cause of the higher education of women, and took a leading part in the foundation of the County School for Girls in Bangor. At this time he was also an enthusiastic mountaineer, and made weekly excursions with some of his colleagues into the Welsh hills. He was a strong swimmer, and rarely missed his morning bathe in the Menai Straits.

Gray succeeded Kelvin as Professor of Natural Philosophy at Glasgow in 1899, winning the chair against strong competition. He held this chair for twenty-four years, stepping down in 1923, shortly before his death. Whitehead writes [1]:-

Gray's principal achievements were as an indefatigable teacher, including extension teaching, and university administrator. Where Kelvin might easily have fallen foul of modern teaching quality assessments, Gray's attention to detail, his advice and guidance to students, kindness, and pastoral care would have seen him through with flying colours. As a result the number of students taking the various natural philosophy classes in the university increased enormously, though few of them were inspired to greatness as many were by Kelvin's exciting but, for the ordinary student, execrable lectures. Gray reorganized the obsolete department he inherited at Glasgow, and founded the Natural Philosophy Institute in 1906, the largest building devoted to physics in Britain; by 1923 more than 600 students a year took laboratory courses there.

Gray married Annie Gordon; they had four sons and four daughters. One of their sons, James Gray, has a biography in this archive.

On 5 March 1883, Gray was elected a fellow of the Royal Society of Edinburgh. He was proposed by William Thomson (Lord Kelvin), James Thomson Bottomley, James Thomson, and James Gray McKendrick. He served the Society as a Councillor during 1903-6, then as Vice-President 1906-9. Gray was also elected to the Royal Society of London, becoming a fellow in 1896.

Gray wrote a number of excellent books and published many papers in the Proceedings of the Royal Society of Edinburgh and of the Royal Society of London. Among his books are Absolute Measurements in Electricity and Magnetism (1883), Theory and Practice of Absolute Measurements in Electricity and Magnetism (Vol. 1, 1888, Vol. 2, 1893), Magnetism and Electricity (1898), which [3]:-

... did much to make experimental electricity an exact science ...

and Dynamics and Properties of Matter (1901). Gray published two important books written in collaboration with others, the first being Treatise on Bessel functions (1895) written with G B Mathews, then in 1911 he published Dynamics written jointly with his son James Gray. The first of these was revised by Gray in 1922 in collaboration with MacRobert. Gray's final major work was Treatise on Gyrostatics and Rotational Motion (1919). He published The Scientific Work of Lord Kelvin in 1908, the year following Kelvin's death, which was expanded from an oration he delivered in 1907 on the death of Kelvin.

Towards the end of his life, Gray spent his holidays in the Perthshire mountains enjoying this as much as he had the Welsh hills during his period in Bangor. Also during this latter period of his life he joined the Edinburgh Mathematical Society in June 1922.

Whitehead writes [1]:-

1. Biography by R R Whitehead, in Dictionary of National Biography (Oxford, 2004).
2. Andrew Gray (1847-1925), Proc. Roy. Soc. 110 (1926), xvi-xix.
3. Andrew Gray, Proc. Roy. Soc. Edinburgh 45 (1924-25), 373-377.