Fig. 37.—Catenary curves.
Fig. 38.—Cycloid curve.
the following method. Draw the vertical diameter of the circle D C. Draw D M at right angles to D C, and make it three times the length of the radius of the circle; make an angle of 30° at E, and draw a line parallel to D M of any convenient length. The line E L making the angle of 30° cuts C B in L. Join M L. M L is the approximate length of half the circumference. Make A C and C B each equal to M L. Then A B is the length approximately of the circumference, drawn at right angles to C D on which the circle rolls. Divide now half the circle into eight equal parts, and draw a line from E S parallel to A B, and equal to M L. Divide E S into eight equal parts. From the points 1, 2, 3, &c., draw lines parallel to A C. With centres 1´, 2´, 3´, &c., and with radius E C, describe arcs cutting them at 1´´, 2´´, 3´´, &c. The curve A D, which must be drawn by free-hand, will then pass through these points. Complete the cycloid by drawing D B in a similar manner. The length A B can also be found approximately by dividing C D into seven equal parts, and taking A B = 22 of those parts.
GLOSSARY OF TERMS USED IN ORNAMENT
Many of the terms which appear in this Glossary have been explained in the previous chapters. The reader should refer back to the text when any of the terms are inadequately described here.
Æsthetics, the science of the beautiful.
Æsthetic, when applied to ornament, not only means “beautiful,” hut that beauty was the sole aim of its production, and distinguishes it from symbolic and mnemonic ornament. See page [143].