wishing to keep prominent in these lectures--that architectural design, rightly considered, is based on and is the expression of plan and construction. In Greek columnar architecture the salient feature of the style is the support of a cross lintel by a vertical pillar; and the main effort of the architectural designer is concentrated on developing the expression of the functions of these two essential portions of the structure. The whole of the openings being bridged by horizontal lintels, the whole of the main lines of the superstructure are horizontal, and their horizontal status is as strongly marked as possible by the terminating lines of the cornice--the whole of the pressures of the superstructure are simply vertical, and the whole of the lines of design of the supports are laid out so as to emphasize the idea of resistance to vertical pressure. The Greek column, too, has only one simple office to perform, that of supporting a single mass of the superstructure, exercising a single pressure in the same direction. In the Gothic building the main pressures are oblique and not vertical, and the main feature of the exterior substructure, the buttress, is designed to express resistance to an oblique pressure; and no real progress was made with the development of the arched style until the false use of the apparent column or pilaster as a buttress was got rid of, and the true buttress form evolved. On the interior piers of the arcade there is a resolution of pressures which practically results in a vertical pressure, and the pier remains vertical; but the pressure upon it being the resultant of a complex collection of pressures, each of these has, in complete Gothic, its own apparent vertical supporting feature, so that the plan of the substructure becomes a logical representation of the main features and pressures of the superstructure. The main tendency of the pointed arched building is toward vertically, and this vertical tendency is strongly emphasized and assisted by the breaking up of the really solid mass of the pier into a number of slender shafts, which, by their strongly marked parallel lines, lead the eye upward toward the closing-in lines of the arcade and of the vaulted roof which forms the culmination of the whole. The Greek column is also assisted in its vertical expression by the lines of the fluting; but as the object of these is only to emphasize the one office of the one column, they are strictly subordinate to the main form, are in fact merely a kind of decorative treatment of it in accordance with its function. In the Gothic pier the object is to express complexity of function, and the pier, instead of being a single fluted column, is broken up into a variety of connected columnar forms, each expressive of its own function in the design. It may be observed also that the Gothic building, like the Greek, falls into certain main divisions arising out of the practical conditions of its construction, and which form a