iij are shown us z in. x 6 in. floor joisting, and the props should be notched over them to prevent being knocked aside. This is better than nailing, for the subsequent removal. The panel shuttering should not be fitted tightly; allowance should be made for swelling.
In drawing the example, get in the main features or outlines first, leaving details until later.
The column, being the principal object in the drawing, may well form the starting-point, then the four troughs.
Portions have been purposely omitted from the example to show the construction clearly, and. apart from the numerous details which simply require carefulness on the part of the draughtsman to place correctly, anyone who has worked through the previous examples should be able to reproduce this.
Chapter VIII PERSPECTIVE OK RADIAL PROJECTION
Definitions anil Principles. The l imiting Cone of Visual Rays. A Simple Method of producing a Perspective irom the Plan —its limitations. Examples—with instructions for draw ing. A Rectangular Frame. A Stone Pedestal. A 1 ,arge Chest. A Pedestal or Office Table. Method of determining the Vanishing Planes—when a vanishing point is not available. Obtaining the Perspective Reduction when Vanishing Points are out of limit
Thf method of perspective projection here described is a variation of the more elaborate process used by artists n preparing pictures. The principles involved are the same, but the method of application is simplified. Of course the method has its limitations, but it has sufficient scope to embrace all the requirements of the student of technical drawing. The limits of this book compcl restriction to a few elementary examples. The purpose of perspective drawing is to represent objects as they appear to the eye when viewed in certain defined positions and distances from the observer, which is the essential difference between this class of drawing and the others dealt with in this book, wherein no consideration is given to the position or distance of the object represented.
Definition of Terms and Symbols used in Perspective.— It is assumed as a principle in this form of perspective drawing that rays of light pass in straight lines from every portion of the object to the eye of the observer, forming, as
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