Professor Aitken, who retired on 30th September 1965 under the age limit, occupies a very special place in the esteem and affection of his colleagues in Senate and Faculty. His altogether unique combination of a most brilliant and wide-ranging intellect with a profound insight into human nature, born of ordeals in war and peace, are enough to have set him above and apart from his fellows, yet his essential humility and childlike directness have made it possible for all sorts and conditions of men to share his gifts of intellect and understanding according to their capacity, and count themselves enriched thereby.
Aitken was born in New Zealand and came to Europe in the First World War to serve at Gallipoli and on the Somme, where he was wounded. He then returned to New Zealand to study Classics and Mathematics in the University of Otago. After obtaining a First in classics, he taught this subject in school, but he was much more interested in Mathematics, although at this time he had little contact with the modern aspects of the subject. In 1923 he came to Edinburgh to study for a Ph.D. Degree under Professor Whittaker. He found the solution of a sixth order difference equation which arose in Whittaker's Theory of Graduation, a problem which suited his special gifts in manipulative algebra and numerical skill. This work was of such merit and originality that he received in 1925 not the Degree of Ph.D, but that of D.Sc.
In 1925 he was appointed Lecturer, and then became Reader, in Mathematics. From his pen came a constant stream of original contributions, mostly in numerical mathematics, in the theory of matrices and determinants, and in the mathematical theory of statistics. Aitken's astonishing and uncanny powers of computation and his remarkable memory are legendary. They contribute to a practical approach to mathematics which has enabled him the more readily to see the solutions of mathematical problems as well as to suggest many new practical methods to his colleagues.
Aitken was elected a Fellow of the Royal Society of Edinburgh when he was only 30 and maintained an active interest in the Society throughout his career, publishing much of his original work in its Proceedings. The Society awarded him its Makdougall-Brisbane Prize in 1933 and the Gunning Victoria Jubilee Prize, the highest award in its gift, in 1953. He was elected a Fellow of the Royal Society in 1936.
In 1932 he collaborated with H W Turnbull in a textbook, The Theory of Canonical Matrices, which has become a classic. He and D E Rutherford edited a series of texts on University Mathematics in which he wrote the first two volumes himself
In 1946 Professor Aitken - an obvious and natural choice - succeeded Whittaker in the Chair of Mathematics. Fortunately, this did nothing to interrupt the flow of original contributions to his subject which has continued until the last two or three years when ill-health has intervened. With his chair came the inevitable administration which he really did not like very much, but which he nevertheless carried out with conspicuous efficiency. He contributed a great deal on University Committees and on Senatus whose sometimes rather heavy business he could suddenly illuminate by some unexpected turn of thought or expression, or enliven by short and penetrating remarks delivered with puckish humour. His lecturing was brilliant and inspired generations of students, both undergraduate and post-graduate.
Edinburgh has always had a great attraction for him and he has resisted the many offers tempting him to go elsewhere. It has most of what he wanted, a congenial job, hills to walk on, and above all, music, concerts, and musical friends. He is a fine (largely self-taught) violinist and viola-player, and a very knowledgeable musician, inspired by personal association with Sir Donald Tovey. Indeed, he is reliably reported as having said that he spent three-quarters of his time thinking about music. This remark reveals how efficiently he must have used the other quarter! He is moreover a creative artist, though only a few intimate friends have been privileged to know his compositions, occasional poems, and the eloquent calligraphy of his manuscript copies of Bach. But to the public he has permitted one particular facet of his artistry to be revealed through the telling of his war experiences, that had affected him so deeply, in his recently (1963) published book Gallipoli to the Somme.
The University is much the poorer for Aitken's retirement, and we, his contemporaries, have already missed him from among us. Mathematicians of the future have the written evidence on which to appreciate his contributions to science, and to say how fortunate Edinburgh has been to have him.