WHEN different fields of inquiry have been separately cultivated for a while, the borderlands between them often provide fertile ground for new investigations. It is in one of these fruitful borderlands that Dr. Hexter has turned a furrow. His book will be of interest alike to students of the business cycle and to those whose more immediate concern has been with vital statistics and with other records of measurable social phenomena.
This does not mean that the field Dr. Hexter has tilled is altogether new. Ever since Malthus, men have been interested in the response of the movement of the population to variations in economic conditions. In particular the relation between fluctuations of the marriage-rate and the movements of various indexes of economic welfare has been a favorite subject of inquiry. Various statisticians have also given passing attention to such seasonal variations of vital phenomena as are fairly well defined. And in recent years, with growing interest in the problem of the business cycle, several investigators have made preliminary surveys of the cyclical movements of different types of non-economic phenomena.
But although Dr. Hexter has had predecessors, whose results he has been careful to take into account, a large part of what he has accomplished is pioneer work. This shows itself, not only in his results, but also in his methods. He has utilized a compact body of fairly homogeneous materials, relating, for the most part, to a single city. His tools are as precise as any the present development of statistical technique affords. In particular he makes skill-