AËRIAL NAVIGATION A POPULAR TREATISE ON THE GROWTH OF AIR CRAFT AND ON AËRONAUTICAL METEOROLOGY BY ALBERT FRANCIS ZAHM, A.M., M.E., PH.D. SECRETARY OF THE AËRO CLUB OF WASHINGTON; GOVERNOR OF THE AËRO CLUB OF AMERICA; GENERAL SECRETARY OF THE INTERNATIONAL CONFERENCES ON AËRIAL NAVIGATION IN 1893 AND 1907; OFFICIAL AMERICAN DELEGATE TO THE AËRONAUTIC CONGRESS OF 1900; FORMERLY LECTURER ON MECHANICS IN THE UNITED STATES BUREAU OF STANDARDS, AND PROFESSOR OF MECHANICS IN THE CATHOLIC UNIVERSITY OF AMERICA [Illustration] NEW YORK AND LONDON D. APPLETON AND COMPANY 1911 COPYRIGHT, 1911, BY D. APPLETON AND COMPANY _Published September, 1911_ Printed in the United States of America PREFACE The purpose of this work is to portray in popular terms the substantial progress of aëronautics from its earliest beginning to the present time. Beyond the introductory account, little note is taken of experiments, however picturesque or clever, which constitute no advance in the art, or lead to no useful result. At times some minutiæ are presented to complete the story of an important series of achievements; but the unproductive efforts of impractical zealots, however prominent or widely known in their day, receive scant, if any, attention. Failures and tragedies where introduced, are described for the lessons involved rather than for any curious interest investing them. The griefs and grotesque follies of aëronautic imbeciles form a long story, but a futile and unprofitable one, of slight concern in the evolutionary history of a veritable science.