Mechanical Drawing Self-Taught (Illustrated)

The object of this book is to enable the beginner to learn to make
simple mechanical drawings without the aid of an instructor, and to
create an interest in the subject by giving examples such as the
machinist meets with in his every-day workshop practice. The plan of
representing in many examples the pencil lines, and numbering the order
in which they are marked, the author believes to possess 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 were 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 numbered in the order in which they were
marked. This prevents a confusion of lines, and makes it more easy to
follow or to copy the drawing.