Excerpt from The Art of Aviation: A Handbook Upon Aeroplanes and Their Engines, With Notes Upon Propellers Primarily with regard to safety. It is a well-known fact that in order to maintain reasonable stability in the air, it is necessary that the maximum velocity of the machine should be about twice the velocity of any gust which it is likely to encounter. It must be borne in mind that one depends entirely Upon one's velocity relatively to that of the surrounding atmosphere, for sustentation, and that if these relative velocities are not maintained, the sustentation at once diminishes, and the machine comes to earth. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.