Geometrical drawing is the art of representing, to the eye, the problems “worked out” by geometricians, and the importance of a knowledge of geometrical drawing is paramount. The student will find that the figures delineated and explained in the next few pages constantly occur in mechanical drawing. Says Walter Smith, State Director of Art Education in Massachusetts, “I have never known a case where a student did not progress more satisfactorily in his studies after a course of practical geometry.”
The elementary conceptions of geometry are few:
1.—A point.
2.—A line.
3.—A surface.
4.—A solid, and
5.—An angle.
All of which elements are used in mechanical drawings.
From these, as data, a vast number of mathematical problems have been deduced; of which a few of the most elementary will be illustrated in this work; but these few will repay the attention of the student.
In “freehand” drawing the crayon and pencil are used; in geometrical drawings the dividers, as shown in illustration, [fig. 97], together with a rule, are all that is necessary to accomplish the work.
A problem is something to be done, and geometry has been defined as the science of measurement; the relation between geometry and mechanical drawing is very close, hence the term “geometrical problem.”
Fig. 97.
