In the course of an investigation that was recently being made into the rate of mortality prevailing among a body of assured lives subject to extra risks, it occurred to me that it would be advisable. if possible, to procure some standard of comparison in addition to the ordinary mortality tables at present in use, it being apparent that the rate of mortality in question would depart too markedly from the existing tables for them to serve as any criterion. Several modes of forming hypothetical tables exhibiting features similar to those characterizing the actual observations—namely, an increased rate of mortality, especially heavy at the earlier ages—suggested themselves to me; but the difficulty of fixing the degree in which they should differ from the table on which they were to be based, and the arbitrary nature of the assumptions it was necessary to make, were obstacles I was unable to remove in a satisfactory manner. Finally, influenced, among other considerations, by the practice in vogue with Life Assurance companies of the present day, I selected the basis explained in the following article, and deduced a table of mortality from the HM 3 per-cent whole-life pure-premium increased at each age by the net addition of 01.