The materials, again, employed in architecture, have influenced most decidedly its forms and character. This has been the case, not only in the peculiar styles which have separately been adopted in different countries, but in the general and essential principles of the science. The materials of which buildings, in all ages, have been chiefly constructed, are stone, wood, and factitious substances, are tiles and bricks. The first adopting of these materials, and, of course, the style of building, must have been recommended by the resources of the country. The law, however, which determines their arrangement is universal, arising from exigencies over which taste, and even ingenuity, exert limited control. This evidently arises from the nature of the question; for, since a mass of stone is heavier in all, and weaker in most positions, than timber of equal dimensions, the whole congeries of supporting and supported members--that is, the whole system of architecture will be affected as the one or the other material is employed. Thus, in wooden erections, the supporting members may be much fewer and less massive than in structures of stone; because, in the former, the horizontal or supported parts are both lighter, and will carry an incumbent weight--as a roof--over a much wider interval than in the latter. It is apparent, also, even for the ordinary purposes of stability, that, in constructing edifices of stone, whether of the perpendicular or horizontal members, the dimensions would be greater than in elevations of wood; and in the case of columnar structures, that the altitude, in proportion to the diameter, would be far less in stone than in timber supports. Hence, the two grand characteristics of a massive or solemn, and a light or airy, architecture. Hence, also, when genius and taste had begun to consider the arrangements of necessity and use in the relations of effect and beauty, new combinations would be attempted, which approached to one or other of these leading divisions. It must, however, be obvious, that the field of these experiments is narrowed by the very principles on which they would be first suggested. In the art we are now considering, the human agent has less power over the inertness of matter than in any other. Imagination comes in contact with reality at every step, and the laws of nature impress the boundaries of that reality, not at the risk of absurdity, but of very being. Beauty becomes here, not the creation of fantasy--a something pleasing only as it reflects our associations, or harmonizes with our feelings; but is more especially the creation of science--the object of demonstrative wisdom. Hence, perfect architectural beauty is the most sublime and the most rational of the objects of taste; because, while the susceptibilities of mind are awakened, the powers of judgment are gratified, by the certainty with which the sources of pleasure can be traced. We feel the arrangement to be beautiful; we know that it is