The name of Lewis P. Orr is an honoured one in the history of medico-actuarial literature. It may well be claimed that his paper on “The selection of lives”(T.F.A. 8, page 103) and the revised edition (T.F.A. 13, page 181) were for many years the standard British works on the medical aspects of life assurance underwriting. His earlier paper (T.F.A. 6, page 55) on “Research in life assurance”—submitted to the Faculty in 1911—may, in its consequences, have been even more important because it set the actuaries of the time thinking, and from that, years later, arose the Continuous Mortality Investigation of the Institute and Faculty of Actuaries; but it is with the subject of the two later papers that we are now concerned.