Plate 20
The Curve of Force
Valuable Curves
Turning to [Figure 70], [Plate 20], we find that whenever nature desires to support a weight she is inclined to use a peculiar curve seen at F. Possibly through continued observation the eye has associated this curve with strength or supporting power. [Figure 71] has detailed this curve. It is found to consist of a long, rather flat portion with a quick and sudden turn at its end. The curve is known to designers as the Curve of Force and is most valuable in all forms of enrichment. Designers even in early ages used it in some form as will be noted from the fragment of Greek sculpture in [Figure 72]. Its beauty rests in its variety. A circle has little interest due to its rather monotonous curvature. The eye desires variety and the curve of force administers to this need and gives a sense of satisfaction. As designers on wood, how are we to utilize this curve for purposes of outline enrichment?
An Approximate Curve of Force
For approximate similarity of curvature an ellipse constructed as shown in [Figure 73] will be found convenient. By drawing several ellipses of varying sizes upon sheets of tin or zinc, a series of templates of utmost practical value may be formed and used as was done in securing the curves of force in [Figures 74] and [75]. If the rail or shelf is longer than the post, measured downward from the rail to the floor or to the next shelf, the ellipse should be used with its major axis placed in a horizontal position, [Figure 75]. If, on the contrary, the post is longer than the shelf the ellipse should have its major axis in a vertical position, [Figure 74]. [Figures 76] and [77] show other instances of the use of the approximate curve of force. Many similar practical applications will occur to the designer.
Mouldings
We have classed the bracket as a link connecting a vertical and horizontal structure. Mouldings may likewise be considered as links connecting similar horizontal or vertical surfaces by bands of graded forms. Inasmuch as they effect the outline they are considered in this chapter. As the mouldings are to assist the eye to make the jump from one surface to another by easy steps, the position from which the mouldings are to be seen determines to some extent their design.