Chapter III discusses combining rectangular and round forms found in nature and applying them to drawing objects like stools and chairs. It explains drawing a stool by first understanding how to draw a box, then applies similar geometric and perspective principles to the stool's structure. The chapter emphasizes utilizing geometric and perspective plans to accurately depict shapes and dimensions.
CHAPTER III.
DRAWING FROM NATURE BODIES THAT COMBINE RECTANGULAR OR CUBIC FORMS AND CIRCULAR OR SPHERICAL FORMS.
This chapter, as seen from the title above, will consist of applications that belong to the previous two chapters. It is the combination of these two forms, rectangular and circular, cubic or spherical, found in most objects that catch our eye and that we may need to draw from nature.
Drawing a stool, a chair, an armchair, etc., from nature.
Knowing how to draw a box, you will be able to draw the stool, plate 5, figure 2. Indeed, the geometric plan of the box, figure 1, ABCD, is it not the same as the geometric plan abcd, forming the front of the stool, figure 2? Is the perspective plan DCFI of the box, figure 1, not the same as the perspective plan dcfi, or top of the stool? Finally, is the perspective plan BEFC of the box and the perspective plan befc of the side of the stool not absolutely the same?
To draw the stool, you can therefore begin by proceeding as if you were to draw a box of similar dimensions. This box will give you the plans or faces of the stool. You will then draw the legs of the stool, comparing their width with their height: you take this width from the width already found from the box. If these legs are square, each of them will present you a geometric plan and a perspective or receding plan, and the top of each of these legs being a square placed horizontally becomes a perspective plan. If these legs are round, the top of each is a circle placed horizontally, and consequently, an ellipse.
One seeks, by comparing, to determine at what height the stick gh, figure 9, attaches, going from one leg to the other. This stick, being in the geometric plan and parallel to the base of this plan, is a horizontal line. The stick mn, being in the perspective plan and parallel to the base of this plan, will take the direction of the lines be, ef, and al. Thus, after finding the box representing the body of the stool, one can find the point of convergence of this box (see plate 3, fig. 10), and then draw to this point the lines that will give the sticks and the various receding lines found in the perspective plans of this stool.
Translation Notes:
"Plan géométral" refers to a geometric or orthographic plan, a method of representation where objects are drawn to scale but not in perspective. "Plan perspectif" refers to a perspective plan, representing how an object appears to the eye based on spatial arrangement.