1. Like all sciences, actuarial science has been developed piecemeal. From time to time theory has been constructed attempting to systematize and unify practices which had already been adopted by the working actuary. In the case of the general treatment of the derivation of rates of decrement from data, little has been published in the Journal to unify the various methods and techniques since W. J. H. Whittall's well-known paper written in 1893 just prior to the commencement of the investigation into the British Offices experience.