That invention was the arch, a curved structure originally made of separate stone or brick segments.
这一发明就是拱门,一种最初由分段的石头或砖块组成的弧形结构。
3
The crawl space beyond had a floor of unpainted, unvarnished wood, and narrow walls of brick. The three-foot ceiling was curved in an arch. It looked like a chimney lying on its side.