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COPYRIGHT, 1932, 1933 BY ERVIN S. FERRY

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This book or any part thereof must not be reproduced in any form without the written permission of the publisher.

Printed in U. S. A.

12-43

Gyrodynamics is the brain child of the pure mathematician. From the beginning it was hedged about by a wall of differential equations. Some engineers and physicists have broken through this wall and have elicited the aid of gyrodynamics in producing marvels greater than those of fabled Daedalus. Already, through its aid, we have a device used on nearly all war ships and on many

of the larger merchant ships by means of which the ship can be guided on any desired straight course without the aid of a helmsman; another that will keep an airplane level and on a straight course even though the aviator may be out of the cockpit making

some necessary adjustment to the engine; another that will keep a submarine torpedo on either a straight or a curved course and, after the torpedo has run a predetermined distance, change the course by a predetermined angle; another that will prevent the rolling of a ship of any size even on a rough sea; another which, carried on a train running at ordinary speed, will record all irregularities of the track traversed. There are many important instruments used in aviation, navigation and in the industries, that are based upon the principles of gyrodynamics. Stresses are developed in the structure of ships, airplanes and other vehicles carrying rotating machinery that can be computed and guarded against only by a designer familiar with gyrodynamics

The purpose of the present book is to bring gyrodynamics out from behind the integral signs and to present it to the acquaintancw of engineers and students having the mathematical equipment of the ordinary graduate of engineering or physics. This book is the( outgrowth of lecture notes of a course that has been given for several years. The first stage in the development of the tours( was the collection of information of all gyroscopic devices of industrial importance. All of the United States patents and many foreign patents granted on gyroscopic apparatus since 1900 have( been examined. Correspondence has been carried on with many firms and individuals. The test of a ship stabilizer in Philadelphia has been watched. Two factories making gyro-compasses in Brooklyn and the gyro-compass school in the Brooklyn Navy