Before proceeding to describe the mortality experiences made use of in this investigation, I will first of all discuss the various materials that have been used in investigations into the mortality among assured lives, the methods of arranging those materials in order to deduce the rate of mortality, and the method of graduation best adapted for the adjustment of the rate of mortality among recently-selected lives, pointing out the advantages and disadvantages of each, and stating which I have adopted. This will necessarily partake more or less of the nature of an historical sketch; but I think it will conduce to clearness, and will, I trust, prove interesting as well as instructive. I have also thought it desirable to state somewhat fully the information on which I have based my conclusions, in order that my readers may be in a position to exercise an independent judgment.