Although more than half a century has elapsed since attention was first drawn to the effect of selection upon the mortality among insured lives, the subject seems to have received but little consideration, partly on account of the numerous other questions pressing for solution, and partly, I dare say, on account of the scanty materials in existence; and it is only within the last decade that interest in it has been revived, and it has taken the place in the actuarial world which its importance demands. This is, in a great measure, due to the valuable collection of statistics published by the Institute of Actuaries in 1869, which has been the fountain-head of many interesting papers, as it furnished investigators with ample materials for their researches into the mortality among insured lives, and especially in the determination of the vexed question of “selection.” Before selection was understood, or rather, I should say, given effect to, it was thought sufficient to group together all the lives of the same age irrespective of the length of time for which they had been assured, and then to deduce the rate of mortality; but the introduction of select lives at old ages reduced the rate of mortality among those who had entered at young ages, and thus an exaggerated view of the probable longevity of young lives was obtained. Consequently, as the annuity-values for young ages by this method are greater than those obtained when selection is taken into account, it follows that young lives were charged too low a rate of premium, while old lives were charged too high a rate.