THE COMPLETE AIRMAN, BY G. C. BAILEY. INTRODUCTION. THIS book aims at providing the airman with a reasonably complete outline of such knowledge as he ought to possess. The title, Airman, designates primarily the pilot, together with all who actually fly, but it is also intended in its wider application to include the director, the manager, etc., of commercial enterprises connected with aviation, as well as that very important person, the mechanic, the value of whose interest and intelligent co-operation is, unfortunately, often under-estimated. It is hoped that the book may also prove of interest to persons less directly concerned with its subject. The ideal airman must necessarily be somewhat versatile. He must have in him something of the sailor, the engineer, and the scientist, added to which he must possess more than an average share of common sense. The title, Complete Airman, is inevitably somewhat misleading, since it is obviously impossible to compress within the limited space available in a book of this type more than a very small proportion of the matter which covers so wide a field. The fact that it is written with a view to being of use and of interest to such widely differing classes of airmen further adds to the difficulty of choosing what to include and what to omit. Theory as such has as far as possible been everywhere avoided. The aim throughout has been to enunciate fundamental principles and to point the way to their development rather than to describe the actual practices ultimately resulting from them. No catalogue of isolated facts, however complete, is to be compared, from the point of view of general utility, with a sound knowledge of principles, backed by common sense in their practical application. The illustrations are mainly diagramimatic, and are in all cases designed to make principles clearer and more obvious, The subject-matter of the book has been split up into sections. Each chapter aims at dealing with one of these. The chapters, while thus available separately as a brief study of the particular subject with which they severally deal, nevertheless follow one another in such a way as to form a continuously developing course, which gives to the whole a certain element of completeness. The first four chapters are devoted entirely to theory. The first consists of a brief survey of certain principles of elementary mechanics, together with a few remarks on the flow of air. It is designed to refresh the readers memory as to matters probably less familiar now than in former days...