So many new firms are now entering the aeroplane industry that there is an ever increasing demand for trained mechanics, designers and flyers, and many technical men now working along other lines are taking a keen interest in aeronautical engineering. If the contents of this book will serve to inspire the technical reader to deeper interest and practical research in the fascinating subject of aeronautics, the author will be more than satisfied with the result of his labor. The aeroplane is rapidly assuming a great commercial importance, and there is no doubt but what it will develop into an industry rivaling that of the automobile.

To keep fully abreast of the times in aeronautic development, one should be a constant reader of the excellent aeronautical magazines. Too much praise cannot be given to the aeronautical press in its effort to maintain an interest in this subject, and as with all pioneering movements, these magazines have met with many discouragements and financial setbacks in the earlier days of flying. To the American magazines, "Aerial Age" and "Flying" (New York), the author owes a debt of gratitude for the use of several of the cuts appearing in this book. The English magazines, "Flight," "Aeronautics" and the "Aeroplane," have been similarly drawn on. "Aviation and Aeronautical Engineering" (New York) has suggested the arrangement of several of the tables included herein. All of these papers are of the greatest interest and importance to the engineer, aviator and aero-mechanic.

JOHN B. RATHBUN.

AERONAUTICAL MAGAZINES

The following list of American and English aeronautic publications will be of interest to those who wish to keep in touch with the latest developments in aeronautics:

ENGLISH MAGAZINES.

CHAPTER I. PRINCIPLES OF THE AEROPLANE.