As nearly all those readers whom the subject-matter of the following pages is likely to interest, are already fully acquainted with the nature and acknowledged utility of the Commutation Method, or arrangement of the preparatory Tables for Annuity and Assurance calculations into certain forms called the D,N,S,M, and R columns; it will, therefore, be unnecessary to enlarge on those points; and the facts to be presently adduced will have reference simply to the early history of that system of computation, or, more strictly, to the date when, and the person by whom, it was first really promulgated. In bringing such facts forward, it is requisite to disclaim the remotest intention of urging that full merit is not likewise due to those English writers who have either foreshadowed or extended the method in this country, and who, although not its first discoverers, were undoubtedly its improvers.