VIBRATION PROBLEMS IN ENGINEERING by S. TIMOSHENKO Professor of Theoretical and Engineering Mechanics Stanford University. Second edition published in may 1937. PREFACE TO THE SECOND EDITION: In the preparation of the manuscript for the second edition of the book, the authors desire was not only to bring the book up to date by including some new material but also to make it more suitable for teaching purposes. With this in view, the first part of the book was entirely re written and considerably enlarged. A number of examples and problems with solutions or with answers were included, and in many places new material was added. The principal additions are as follows In the first chapter a discussion of forced vibration with damping not proportional to velocity is included, and an article on self-excited vibration. In the chapter on non-linear sys tems an article on the method of successive approximations is added and it is shown how the method can be used in discussing free and forced vibrations of systems with non-linear characteristics. The third chapter is made more complete by including in it a general discussion of the equation of vibratory motion of systems with variable spring characteristics. The fourth chapter, dealing with systems having several degrees of freedom, is also Considerably enlarged by adding a general discussion of systems with viscous damping an article on stability of motion with an application in studying vibration of a governor of a steam engine an article on whirling of a rotating shaft due to hysteresis and an article on the theory of damp ing vibration absorbers. There are also several additions in the chapter on torsional and lateral vibrations of shafts. The author takes this opportunity to thank his friends who assisted in various ways in the preparation of the manuscript and particularly Professor L. S. Jacobsen, who read over the complete manuscript and made many valuable suggestions, and Dr. J. A. Wojtaszak, who checked problems of ló.