HYDRAULIC TURBINES WITH A CHAPTER ON CENTRIFUGAL PUMPS - 1920 - PREFACE TO THE THIRD EDITION - Since this book was first written, practice has changed to such an extent that many statements, which were true at that time, are not true today. These portions have been entirely rewritten so as to present the very latest features in construction and practice. Also practically every other chapter has been altered and new matter and illustrations inserted, where it was thought that greater clearness could be so attained. The presentation of the theory has been quite carefully considered and has been largely rewritten in order to be more effective. An attempt has been made to so arrange this that the fundamental principles could be grasped without going into a lot of technical details. If desired, certain portions of the latter, of theoretic interest only, can be omitted without brea ing the continuity of thought. Chapters have been added on turbine governors and on the methods of turbine design. The latter has been inserted in order to meet a demand for something on that subject. The methods that are given are those employed by the best designers at the present time. The procedure avoids the old cut and try practice on . the one hand, as well as a highly theoretical treatment, that is of no practical value, on the other. It is rather a happy compromise between the two. The author is still of the opinion that the greater number of engineers are concerned with the construction and operating characteristics of turbines rather than with the details of their design. But there are some phases of turbine performance and construction that can be understood more completely, if approached from the view point of hydraulic design. Questions and numerical problems have been added at the end of every chapter, in order to increase the usefulness of the book for instruction purposes. The questions are intended to call attention to the most important features presented in the chapter and also to bring out more clearly the thought there expressed. The problems are arranged so as to afford applications of the principles stated and are hence quite limited in character. If time available for the course permits, it is thought that problems of a more general character are desirable. But it is believed that it is better for the instructor to prepare these to suit his individual course, and to vary them from year to year, rather than to incorporate such in the book. The notation has been changed slightly in the present edition in order to conform more closely to the standard notation recommended by the Society for the Promotion of Engineering Education. The author is indebted to many teachers and students, who have used the former editions, and also to engineers with whom he has discussed these matters for numerous suggestions which have been helpful to him in the preparation of the present volume. P AS ADENA CA , LIF., February, 1920. PREFACE TO THE SECOND EDITION In addition to correcting typographical errors and rewriting two articles, the issuing of a second edition has afforded an opportunity to add new material which it is believed will increase the sphere of usefulness of the book...