MECHANICAL ENGINEER'S POCKET-BOOK. A REFERENCE-BOOK OF RULES, TABLES, DATĂ, AND FORMULÆ, FOR THE USE OF ENGINEERS, MECHANICS, AND STUDENTS. BY WILLIAM KENT, A.M., M.E., Consulting Engineer, Member Amer. Soc'y Mechl. Engrs. and Amer. Inst. Mining Engrs. FIFTH EDITION, REVISED AND ENLARGED. EIGHTH THOUSAND. NEW YORK: JOHN WILEY & SONS. PREFACE. MORE than twenty years ago the author began to follow the advice given by Nystrom: "Every engineeer should make his own pocket-book, as he proceeds in study and practice, to suit his particular business." The manuscript pocket-book thus begun, however, soon gave place to more modern means for disposing of the accumulation of engineering facts and figures, viz., the index rerum, the scrapbook, the collection of indexed envelopes, portfolios and boxes, the card catalogue, etc. Four years ago, at the request of the publishers, the labor was begun of selecting from this accumulated mass such matter as pertained to mechanical engineering, and of condensing, digesting, and arranging it in form for publication. In addition to this, a / careful examination was made of the transactions of engineering societies, and of the most important recent works on mechanical engineering, in order to fill gaps that might be left in the original collection, and insure that no important facts had been overlooked. Some ideas have been kept in mind during the preparation of the Pocket-book that will, it is believed, cause it to differ from other works of its class. In the first place it was considered that the field of mechanical engineering was so great, and the literature of the subject so vast, that as little space as possible should be given to subjects which especially belong to civil engineering. While the mechanical engineer must continually deal with problems which belong properly to civil engineering, this latter branch is so well covered by Trautwine's "Civil Engineer's Pocketbook" that any attempt to treat it exhaustively would not only fill no long-felt want," but would occupy space which should be given to mechanical engineering. Another idea prominently kept in view by the author has been that he would not assume the position of an "authority" in giving rules and formulæ for designing, but only that of compiler, giving not only the name of the originator of the rule, where it was known, but also the volume and page from which it was taken, so that its derivation may be traced when desired. When different formulæ for the same problem have been found they have been given in contrast, and in many cases examples have been calculated by each to show the difference between them. In some cases these differences are quite remarkable, as will be seen under Safety-valves and Crank-pins. Occasionally the study of these differences has led to the author's devising a new formula, in which case the derivation of the formula is given. Much attention has been paid to the abstracting of data of experiments from recent periodical literature, and numerous references to other data are given. In this respect the present work will be found to differ from other Pocketbooks. The author desires to express his obligation to the many persons who have assisted him in the preparation of the work, to manufacturers who have furnished their catalogues and given permission for the use of their tables, and to many engineers who have contributed original data and tables. The names of these persons are mentioned in their proper places in the text, and in all cases it has been endeavored to give credit to whom credit is due. The thanks of the author are also due to the following gentlemen who have given assistance in revising manuscript or proofs of the sections named: Prof. De Volson Wood, mechanics and turbines; Mr. Frank Richards, compressed air; Mr. Alfred R. Wolff, windmills; Mr. Alex. Humphreys, illuminating gas; Mr. Albert E. Mitchell, locomotives; Prof. James E. Denton, refrigerating-machinery; Messrs. Joseph Wetzler and Thomas W. Varley, electrical engineering; and Mr. Walter S. Dix, for valuable contributions on several subjects, and suggestions as to their WILLIAM KENT, treatment. PASSAIC, N. J., April, 1895. FIFTH EDITION, MARCH, 1900. C. Some typographical and other errors discovered in the fourth edition have been corrected. New tables and some additions have been made under the head of Compressed Air. The new (1899) code of the Boiler Test Committee of the Americar Society of Mechanical Engineers has been substituted for the old (1885) code. W. K. In this edition many extensive alterations have been made. Much obsolete matter has been cut out and fresh matter substituted. In the first 170 pages but few changes have been found necessary, but a few typographical and other minor errors have been corrected. The tables of sizes, weight, and strength of materials (pages 172 to 282) have been thoroughly revised, many entirely new tables, kindly furnished by manufacturers, having been substituted. Especial attention is called to the new matter on Cast-iron Columns (pages 250 to 253). In the remainder of the book changes of importance have been made in more than 100 pages, and all typographical errors reported to date have been corrected. Manufacturers' tables have been revised by reference to their latest catalogues or from tables furnished by the manufacturers especially for this work. Much new matter is inserted under the heads of Fans and Blowers, Flow of Air in Pipes, and Compressed Air. The chapter on Wire-rope Transmission (pages 917 to 922) has been entirely rewritten. The chapter on Electrical Engineering has been improved by the omission of some matter that has become out of date and the insertion of some new matter. It has been found necessary to place much of the new matter of this edition in an Appendix, as space could not conveniently be made for it in the body of the book. It has not been found possible to make in the body of the book many of the cross-references which should be made to the items in the Appendix. Users of the book may find it advisable to write in the margin such cross-references as they may desire. The Index has been thoroughly revised and greatly enlarged. The author is under continued obligation to many manufacturers who have furnished new tables and data, and to many individual engineers who have furnished new matter, pointed out errors in the earlier editions, and offered helpful suggestions. He will be glad to receive similar aid, which will assist in the further improvement of the book in future editions. PASSAIC, N. J., September, 1898. WILLIAM KENT. |