SELF-TAUGHT: COMPRISING INSTRUCTIONS IN THE SELECTION AND PREPARA- ELEMENTARY INSTRUCTION IN PRACTICAL MECHANICAL DRAWING. TOGETHER WITH EXAMPLES IN SIMPLE GEOMETRY AND ELEMENTARY MECH- BY JOSHUA ROSE, M. E., AUTHOR OF STEAM BOILERS," MODERN STEAM ENGINES," "THE COMPLETE PRACTICAL ILLUSTRATED BY THREE HUNDRED AND THIRTY ENGRAVINGS. FOURTH EDITION, THOROUGHLY REVISED AND CORRECTED. PHILADELPHIA: HENRY CAREY BAIRD & CO., INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS, LONDON: SAMPSON LOW, MARSTON, SEARLE & RIVINGTON, LIMITED, IN the pages of this book, the author has sought to impart to the beginner, such elementary information as would enable him, with application and practice, to make simple mechanical drawings without the assistance of a teacher. To accomplish this end, it has been necessary to mainly confine the subject-matter to the actual drawing of elementary pieces of machinery, and in many cases to show the pencil lines of the drawing, which possesses great advantages for the learner, since it is the producing of the pencil lines that really proves the study, the inking-in being merely a curtailed repetition of the pencilling. Similarly when the drawing of a piece, such, for example, as a fully developed screw thread, is shown fully developed from end to end, even though the pencil lines are all shown, yet the process of construction will be less clear than if the process of development be shown gradually along the drawing. Thus beginning at an end of the example, the first pencil lines only may be shown, and as the pencilling progresses to the right-hand, the development may progress so that at the other, or left-hand end, the finished inked-in and shaded thread may be shown, and between these two ends will be found a part showing each stage of development of the thread, all the lines being num (iii) |