Dan Rutherford was one of our oldest and closest friends. His name doesn't appear in the usual reference books but we owed him much and it will take a little time to adjust to the knowledge that he will never again blow into our house in between meetings or trains: with his boyish grin and something important or droll to tell us before rushing off. He hadn't changed much in appearance since our student days. His unruly hair had gone a bit grey and we never saw him wearing a hat. He had a continuously active mind and when he described, as he often did, immensely humorous and complicated things which had happened to him, he would pause and his eyes would light up with laughter as if he had just discovered some new, absurd, and preposterous equation.
He was an outstanding and dedicated mathematician but, with that unworldly honesty which seems to go with first rate mathematicians, he would sometimes say that some young irian in his twenties whom we knew, or he had taught, was better than he could ever be.
He was one of the hardest workers we have ever known and after carrying a large part of the burden in his department as lecturer and reader he would sometimes talk wistfully of a chair. If ever a teacher merited one for service to his department and for eminence in his field, appreciated far beyond St Andrews, he did. We were immensely pleased when he was appointed to the Gregory Chair of Applied Mathematics in 1964.
The reason why this professional recognition was so slow in coming was, we believe, tied up with the fact that Dan Rutherford all his life had a love affair with Scotland. Although an internationalist in outlook, and well travelled, he had decided that Scotland was the only country in which he could happily live and work. For him St Andrews was never a staging point on the way to Oxford or Cambridge and he turned down several offers of chairs in England and overseas.
He didn't go to Oxford or Cambridge for his post-graduate degree in mathematics. Following an old Scottish tradition he went to Amsterdam, where, in order to graduate he had to teach himself Dutch and German. Thereafter, apart from a short spell assisting Professor Whittaker in Edinburgh, and a year as visiting professor in Notre Dame, he spent his entire working life in St Andrews. A work on matrices by him was the first of the Edinburgh University Press publications and in recent years he carried a heavy load in editing international mathematical text books.
Very happily married to one of his former students, he was a man of abstemious habits but the reverse of an ascetic recluse. In the days when we were both students in the general Greek class we were often engaged in mischievous exploits with Dan Rutherford. Elder of the Church he might be in later years but he never lost his sense of the ridiculous.
Like many mathematicians he was a 3-M man, being an addict of mathematics, music and mountaineering. He taught himself to play the piano well and had at least one original composition to his credit. He was also an enthusiastic amateur painter. More than once we have housed a canvas of his destined for exhibition. On the hills he was an splendid companion and we have happy memories of going to his cottage in Glen Lyon to which he invited promising senior students who spent the days in fishing, climbing and botanising with their teacher, and the nights sporting with algebra.
Any interest we have in interior decoration goes back to Dan Rutherford and his wife who in their young married days proved to us that you could make an ordinary house interesting, original, and comfortable on modest means. Although latterly he was a rhododendron and dahlia man he was once much taken up with saxifrages, erica, and gentians, our own garden having benefited from his enthusiasm.
All his life the professor was an ardent sportsman. As a student he played rugby and hockey for the university, stooping, occasionally, to be our tennis partner. Although no expert he could ski and, not long after learning to drive a car, he was able to take part in that virtual Grand Prix, rush-hour traffic on Lake Shore Drive, Chicago. In recent years he liked nothing better than to slip away with his fishing rod.
Dan Rutherford was a natural and patient teacher who found it easy to communicate his enthusiasms. It seems no time since he, a little absently, taught us a new way to extract square roots -- we having forgotten the old way. Last time we saw him he consulted us about a number of Scots who had worked hard for their country whom he wanted to put forward for honorary degrees. He himself had no ambition higher than to use all his talents at maximum pressure in the service of our oldest university. The quiet professor with the soft voice was a wonderful friend, a merry Christian. and tireless in his quest of the good, the right, and the true.
Wilfred Taylor, The Scotsman: November 1966