DRAFTSMEN'S HANDBOOK: CONTAINING TABLES, RULES AND FORMULAS, WITH NUMEROUS EXAMPLES EXPLAINING THE PRINCIPLES OF TO THE MECHANICAL TRADES It is the author's hope and desire that this book, which is the outcome of years of study, work and observation, may be a help to the class of people to which he himself has the honor to belong, the working mechanics of the world. This is not intended solely as a reference book, but it may also be studied advantageously by the ambitious young engineer and machinist; and, therefore, as far as believed practical within the scope of the work, the fundamental principles upon which the rules and formulas rest are given and explained. The use of abstruse theories and complicated formulas is avoided, as it is thought preferable to sacrifice scientific hairsplitting and be satisfied with rules and formulas which will give intelligent approximations within practical limits, rather than to go into intricate and complicated formulas which can hardly be handled except by mathematical and mechanical experts. In practical work everyone knows it is far more important to understand the correct principles and requirements of the job in hand than to be able to make elaborate scientific demonstrations of the subject; in short, it is only results which count in the commercial world, and every young mechanic must remember that few employers will pay for science only. What they want is practical science. Should, therefore, scientific men, (for whom the author has the greatest respect, as it is to the scientific investigators that the working mechanics are indebted for their progress in utilizing the forces of nature),-find nothing of interest in the book, they will kindly remember that the author does not pretend it to be of scientific interest, and they will therefore, in criticizing both the book and the author, remember that the work was not written with the desire to show the reader how vulgarly or how scientifically he could handle the subject, but with the sole desire to promote and assist the ambitious young working mechanic in the world's march of progress. NEW YORK, October, 1899. P. LOBBEN. PREFACE TO SECOND EDITION. The preface to the first edition explains the purpose of the book, and the only thing I have to add is that I wish to express my thanks to the technical press and to the public in general for the friendly spirit in which my work has been received, which has made it possible for me to have the pleasure of getting out this, the second and much enlarged edition. HOLYOKE, MASS., July, 1910. PEDER LOBBEN. PREFACE TO THIRD EDITION. The continued demand for this book has made a reprint advisable, and I have taken the opportunity of correcting some minor errors and revising a few of the tables in the steam section, as well as to make the electrical formulas conform to the new standardization rules NEW YORK, January, 1922. PEDER LOBBEN. |