Fig. 48a. the plan drawings for a box
Next draw one of the sides as shown at [B] and this will give you the height and the length of the box and mark in the sizes, that is 5 and 8 inches accordingly. Finally draw the end and you will have the height and width of the box as shown at [C] and again you mark in the dimensions.
It is easy to see now that if you have all three dimensions, namely length, breadth and thickness, and that if you make a box in wood or metal it will look like the picture shown at [D] which is in isometric perspective.
Fig. 48d. the box drawn in isometric perspective
Isometric Perspective Drawings.
—The kind of perspective drawings I told you how to do under the caption of Drawing in Perspective is true perspective but engineers do drawings which they call isometric perspective, that is, while the object seems to stand out in relief there are no vanishing points.
This kind of perspective is purely mechanical and not in the least artistic but it is a great aid when you intend to make anything, for you can still draw the lines to scale and see exactly how the finished object will look.
To make a drawing of this kind draw a line on a sheet of paper near the bottom and two 30 degree lines from the ends and a vertical line through them where they meet as shown at [A in Fig. 49].
Now there are four ways by which you can get the 30 degree lines on paper and these are (1) to buy isometric ruled paper, that is paper on which the lines are already ruled; you can buy this paper for 15 cents a quire of any dealer in drawing materials or of Keuffel and Esser, 127 Fulton Street, New York City. This is the easiest and best way.