AUTHOR'S PREFACE
ACTUARIAL science is essentially practical in that, whilst it is based on the processes of pure mathematics, the object of the worker must be to produce a numerical result.
For this reason it is necessary for considerable prominence to be given, in the curriculum of the actuarial student, to the subject of Finite Differences, and it thus becomes convenient, in the study of those subjects not included under the heading of Algebra, to deal with this part of the syllabus first and, notwithstanding certain theoretical objections, to treat the fundamental propositions of the Differential and the Integral Calculus as being, substantially, special cases of similar propositions in Finite Differences. The subjects enumerated cover so wide a field that it has been necessary to exercise considerable comand to include only such problems as are requisite for a proper knowledge of the subjects within the syllabus.
In the chapter on Probability it will be seen that the numerical or " frequency" theory of probability has been adopted. Having regard to the practical nature of the actuary's work, it is thought that strict adherence to this aspect of the subject is necessary if the student is to acquire sound views from the outset. The subject of Inverse Probability has been excluded from the examination syllabus in recent years and for this reason it is not introduced into the present work.
In conclusion the author would wish to tender his best thanks to many colleagues and other members of the Institute of Actuaries for their kind assistance and useful criticisms. In this connection he is particularly indebted to Mr G. J. Lidstone, who was good enough to read the chapters relating to Finite Differences and made many valuable suggestions.
A.H. August 1922.
NOTE TO REVISED EDITION
THE first edition having been nearly exhausted in June 1926, Mr Henry was about to undertake, at the request of the Council, the revision of the volume, intending to embody certain minor alterations only in the new edition. Owing to his untimely death in September, the revision has been entrusted to Mr H. Freeman, M. A., F.I.A., who is peculiarly fitted for the task in view of his experience as Official Tutor and his personal knowledge of Mr Henry's intentions in the matter.
J. B.
January 1927.