ELEMENTARY MECHANICAL DRAWINGCHAPTER I INSTRUMENTS AND MATERIALS 1. Introductory.The instruments used in mechanical drawing may be divided into two distinct groups: first, the set of instruments, generally in a case, consisting of a compass, dividers, ruling pens, etc., and second, the drawing board, T-square, triangles, etc. To secure good results in mechanical drawing good instruments are necessary. Economy in the purchase of instruments is unwise, because drawings made with inferior instruments will be of inferior quality in technique. A good set of instruments with proper care will serve the student's needs almost indefinitely. The instruments of the second group, such as the drawing-board, etc., may, however, be of medium grade, if the cost of the very best is prohibitive.The materials used may also be divided into two parts: first, such materials as drawing-paper, tracing-paper, tracing-cloth, and printing-paper; and second, pencils, erasers, inks, etc. The drawing-paper mTable of Contents CONTENTS; Pagi; Preface ^; Introduction' u; CHAPTER I; Instruments and Materials; List of Instruments; Paper and Tracing Clotli L; List of Supplementary Instruments 13; CHAPTER II; The Use op Instruments 20; Scale 20; Protractor 2; Triangles or Set-squares 2; Lead Pencils 2:; Ruling Pen 2!; Compass 3; Dividers 3:; Irregular Curves 3; CHAPTER III; Method of Procedure in Drawing 3; CHAPTER IV; Lettering 4; CHAPTER V; Drawing Room Practice and Conventions 4; Definitions of Drawings 4; Alphabet of Lines 5; Dimensioning 54; Cross-hatching or Cross-sectioning 57; Sections 5; Shade Lines &'; Line Shading (j*; CHAPTER VI; Projections 7; Definitions 7; Perspective Projection