Gibb was elected to our Society in 1910, becoming at the same time a member of the Library Committee. In that capacity and later as Librarian he gave devoted service for twenty-six years, and was also President of the Society during the session 1920-21. He was a graduate of Edinburgh University, which he entered in 1900, and was also a postgraduate scholar, his subject of research being the motion of the satellite of Neptune. After a few years of school-teaching experience, he was appointed in 1909, on the nomination of Professor George Chrystal, to a lectureship in mathematics at the University, and during Chrystal's last illness and for some time after his death Gibb had the chief responsibility. He was thus one of the two lecturers on the staff when E T Whittaker came to the Chair of Mathematics in January 1912, and Sir Edmund has on many occasions given testimony to his own "debt beyond expression" for an unswerving loyalty and service extending over thirty-four years.
In the first World War Gibb was in the Ballistics Department of the Ordnance Committee at the Royal Arsenal, Woolwich, engaged in computing range tables for guns in the Navy and in the Army. One has heard that the high-angle tables required for firing over Gallipoli Peninsula from the Aegean Sea to the Narrows were in part computed by him.
In his earlier years as a lecturer Gibb continued to take an active interest in research. This is attested by published papers on the hypergeometric function, by extensive but unpublished work on Fourier analysis of pulsations from variable stars and, in quite another field, on the theory of Pfaffians, while his interest in computational and statistical mathematics is evidenced by a tract, "Interpolation and Numerical Integration," No. 2 of the Edinburgh Mathematical Tracts, 1915. However, his main task as a mathematician was destined to be in the shaping of the future generation, in lecturing, examining and administration; and fortunate indeed was the University of Edinburgh in that David Gibb devoted the energies of his life to its large mathematical classes. He gave his due share of lecturing to the advanced and intermediate grades, but most of his activity was devoted to first-year elementary classes, the members of which possessed no outstanding aptitude for mathematics. In this connexion Gibb's teaching experience, his knowledge of the background and the conditions of the Scottish educational system, his sympathetic understanding of the difficulties of students in these classes and later, his further experience as an inspector of mathematics in schools, all stood him in good stead.
As an examiner he was particularly expert. He examined regularly for the Preliminary examinations and the Entrance Bursaries. He was also for many years an examiner for The Faculty of Actuaries, and was highly valued by the Faculty and by the University as a liaison officer between them. It would be impossible to imagine anyone more painstaking in the scrutiny and verification of first drafts of examination questions, not only his own but those of everyone else on the staff. Such unobtrusive, self-denying and efficient work must have occupied many thousands of hours.
As Director of Studies and adviser to students Gibb was at his best. His knowledge of the University Calendar, of time-tables, of the ins and outs of rules and regulations, and the intricate connections, and possible collisions between them, was proverbial among his colleagues. Also, being himself an Edinburgh student, he could, draw on his own experience. These qualities, added to a rigorous and tireless conscientiousness, made him an ideal adviser. Constantly one could observe to what endless trouble he would go to map out the best course for any student, with what unsparing exertions he would try to alleviate the pressure of any conflict of regulations. Doubtless it is true that some students felt at first that Gibb's recommendations left them less latitude than they might have wished; few could persist in this impression for long. Certainly none was ever left in any doubt as to what the advice actually was; it was given in the forthright voice and manner of the kingdom of Fife, of which Gibb was a loyal and worthy son. Students have invariably recalled, however, that their first feelings of awe and fear changed, with time and deeper knowledge, to respect and affection. It is difficult to put into words that combination of severity and sympathy that enabled Gibb, from a serious experience of life, to give counsel or unobtrusive help to his colleagues. They for their part accorded to him, instinctively, a patria potestas. He is remembered as a notable teacher of mathematics in Scotland, but even more as a man of complete and uncompromising integrity, of unstinted devotion to service, grave and severe when necessary but also full of human sympathy and, on occasion, humour. These elements were mingled in him. His death has brought a very great loss to our Society.