There are many curved objects around us whose drawing is more demanding than that of silos, cans, trees, and vases. One of the most familiar is the arch. Arches come in all sizes and shapes, some elliptical, some circular, some parabolic, and others rather free-form.
Arches such as those built into many bridges and public buildings provide attractive shapes for drawings and paintings. Some are complex and defy any easy approach to their drawing, but most can be constructed using some of the basic ideas we've already explored. Suppose we have a simple bridge, such as the one top right.
We'll assume the top of the bridge is a level roadway without any curvature, although most bridges rise some toward their midpoints. Once you get a basic ...