chapter  6
18 Pages

Arches and catenaries

The brick arch and the stone voussoir arch may be taken as the first fully developed forms. Neither exists as a direct natural prototype, nor do we find the monolithic natural arch [4.2] in any of the areas where they first appeared. Among the early man-made forms that may have contributed to their development are (1) a fairly straight copy of the accidentally-wedged boulder [6.1]; (2) the alternative simplest form consisting of two long blocks of stone inclined inwards to meet as an inverted V [6.2]; and (3) the equivalent of the latter consisting of two logs similarly inclined towards each other, or two lighter saplings or bundles of reeds set more vertically in the ground and then bent over until their free ends met and could be tied together, much as in the hut in Figure 1.1.