When I was invited to deliver this lecture I proposed to deal with some aspects of Aeroplane Photographic Survey in which I have been especially interested, but in view of an event which happened on October 13, 1923, viz., the death of Major J. C. Griffiths in a flying accident at Coventry, I have felt that it is my duty to devote some part of this lecture to a consideration of the contributions made by my late friend to the advance of our knowledge of some of the fundamental features underlying the practice of aerial survey. For morethan three years, Griffiths, working under the direction of Prof. B. M. Jones, toiled at certain problems which were by no means easy to attack, which were absolutely of first-rate importance as a basis for certain types of survey work, and which when fully investigated provided results which had nothing spectacular about them, but which have laid a firm foundation for future work. Underconditions which were seldom easy and were frequently most discouraging, he worked unremittingly towards the solution of the problems which he was investigating, and has produced results which are of lasting worth.