PREFACE THIS book has been written especially for Engineers and Students who already possess a fair knowledge of Elementary Mathematics and Theoretical Mechanics; it is intended to assist them to apply their knowledge to practical engineering problems. Considerable pains have been taken to make each point clear without being unduly diffuse. However, while always aiming at conciseness, the short-cut methods in common use have often-and intentionally-been avoided, because they appeal less forcibly to the student, and do not bring home to him the principles involved so well as do the methods here adopted. Some of the critics of the first edition expressed the opinion that Chapters I., II., III. might have been omitted or else considerably curtailed; others, however, commended the innovation of introducing Mensuration and Moment work into a book on Applied Mechanics, and this opinion has been endorsed by readers both in this country and in the United States. In addition to the value of the tables in these chapters for reference purposes, the worked-out results afford the student an opportunity of reviewing the methods adopted. The Calculus has been introduced but sparingly, and then only in its most elementary form. That its application does not demand high mathematical skill is evident from the working out of the examples in the Mensuration and Moment chapters. For the benefit of the beginner, a very elementary sketch of the subject has been given in the Appendix; it is hoped that he will follow up this introduction by studying such works as those by Barker, Perry, Smith, Wansbrough, or others. For the assistance of the occasional reader, all the symbols employed in the book have been separately indexed, with the exception of certain ones which only refer to the illustrations in their respective accompanying paragraphs. In this (fourth) edition, some chapters have been considerably enlarged, viz. Mechanics; Dynamics of Machinery; Friction; Stress, Strain, and Elasticity; Hydraulic Motors and Machines; and Pumps. Several pages have also been added to many of the other chapters. A most gratifying feature in connection with the publication of this book has been the number of complimentary letters received from all parts of the world, expressive of the help it has been to the writers; this opportunity is taken of thanking all correspondents both for their kind words and also for their trouble in pointing out errors and misprints. It is believed that the book is now fairly free from such imperfections, but the author will always be glad to have any pointed out that have escaped his notice, also to receive further suggestions. While remarking that the sale of the book has been very gratifying, he would particularly express his pleasure at its reception in the United States, where its success has been a matter of agreeable surprise. The author would again express his indebtedness to all who kindly rendered him assistance with the earlier editions, notably Professor Hele-Shaw, F.R.S., Mr. A. H. Barker, B.Sc., Mr. Andrew Forbes, Mr. E. R. Verity, and Mr. J. W. Jukes. In preparing this edition, the author wishes to thank his old friend Mr. H. Rolfe for many suggestions and much help; also his assistant, Mr. R. H. Duncan, for the great care and pains he has taken in reading the proofs; and, lastly, the numerous correspondents (most of them personally unknown to him) who have sent in useful suggestions, but especially would he thank Professor Oliver B. Zimmerman, M.E., of the University of Wisconsin, for the "gearing" conception employed in the treatment of certain velocity problems in the chapter on "Mechanisms." JOHN GOODMAN. THE UNIVERSITY OF LEEDS, August, 1904. |