Architecture has been classed under two different heads, Grecian and Gothic; the first depends on perpendicular pressure [see fig. 220], the other on lateral pressure [see fig. 221]. By the laws of gravitation, all matter at rest keeps its place by its own weight, or tendency to press downwards; and is only to be removed by superior force acting in a different direction. A perpendicular rock, and a solid wall built upright, will preserve their position so long as the substance, or the materials of which they are composed, retain their power of cohesion; and on this principle all Grecian architecture is founded. Hence have arisen those relative proportions in the different orders, from the heaviest Doric to the most graceful Corinthian, which, after the experience of ages, were deemed fixed beyond the power of improvement; and by these proportions the distances of intercolumniation are regulated according to the strength of the parts supporting and supported.
