1V   PREFACE

PREFACE   v

Yard have been visited. Foreign-built gyro-compasses have been inspected on ships in New York harbor. One summer vacation of three months has been spent in attendance on the Sperry Gyro-compass School. A trip was made to Annapolis and Washington for the purpose of obtaining information on the gyro control of automobile torpidoes and a trip was made to Kiel, Germany, for the purpose of examining the construction of the Anschutz gyro-compass.

The second stage in the development of the course was the deduction of the laws and principles upon which depend the action of the various devices considered, using therein only methods that are understandable by students who are not specialists in mathematics. Equations are derived that can be used for the solution of numerical problems. Careful attention has been given to the construction of clear definitions and diagrams.

The first chapter of the present book is preliminary to the subject of gyrodynamics and includes the definitions and laws of physics assumed in the subsequent chapters. In the second chapter are developed the laws of gyrodynamics upon which are based the various gyroscopic devices used in industry. Many applications and much illustrative material are included as well as a number of solved problems designed to show methods of calculation. The gyroscopic pendulum with such applications as the gyrohorizon and the gyro-sextant are considered in the third chapter. The fourth chapter is devoted to the consideration of anti-roll devices for ships. In the fifth chapter the principles upon which the gyro-compass depends are developed, and each of the five makes of gyro-compass being installed on ships in 1931 is described in some detail. The last chapter considers the dynamic stabilization of a statically unstable body by means of a gyroscope. The methods which have been used for stabilizing monorail cars are described, and the reasons for the lack of success of the models built are indicated.

It is my agreeable duty to acknowledge the aid received from all to whom I have applied. For information concerning the gyrocompass I am indebted to Mr. E. C. Sparling, compass engineer, and to Mr. J. J. Brierly, head of the Gyro-compass School, of the Sperry Gyroscope Company, Brooklyn, N. Y.; to Mr. A. P. Davis, chief engineer of the Arma Engineering Company, Brooklyn, N. Y.; to M. P. Vonderwahl, chief engineer of Anschutz & Co., Kiel; to Mrs. S. G. Brown of the S. G. Brown Company, Limited, London,

England, and to the Director of the Officine Galileo, Florence, Italy. I am under deep obligation to Mr. F. P. Hodgkinson, stabilizer engineer, and to Mr. L. F. Carter, recorder engineer, of the Sperry Gyroscope Company, and to Mr. William Dieter, chief engineer of the E. W. Bliss Company, of Brooklyn, N. Y.

Professor Arthur Taber Jones of Smith College has been so good as to give the manuscript of the present book the same careful reading and scholarly criticism which he has bestowed on my previous books. These criticisms have resulted in a great improvement in the clearness and accuracy of the text.

ERVIN S. FERRY.

LAFAYETTE, INDIANA, U. S. A September 1. 1931.

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