After remarking, that former writers have been una nimous in considering proportions as deriving their ef fects from the original constitution of our nature,—and that they have endeavoured to support this opinion by analogies' drawn from proportions in music and num bers,—and remarking, that all reasonings from such ana logies are too futile to require any attention,—i\Ir Alison proceeds to show, that the beauty of the proportions of this art is resolvable into the principles which have been established, and that they please us not from any original law of our nature, but as expressive of fitness. The pro portions of architecture relate either to its external or in ternal members. The beauty of external proportions, we are informed, arises from their apparent fitness for the habitations of men when viewed from without, and con sists in stability and sufficiency for the support of the roof ; walls in every country, in the same period of time, are nearly of an equal thickness for their stability, and to the support of any weight laid upon them ; and when their distance from each other is suitable, the building is considered as well proportioned ; but when the walls are so thin or high, or placed at so great a distance from each other, as to appear insecure of themselves, or insufficient to support the roof, that building is reckoned to be ill proportioned. Proportion therefore, in those cases, is merely fitness, and this has never been very precisely de termined; we are here guided entirely by experience, and our sentiments respecting proportions are influenced by the nature of the buildings, and the materials of which they are composed. Edifices constructed with wood or brick, admit not of the walls being equally high as if built of stone. A house united with others, may be car ried higher than if placed alone. A tower or spire hav ing only itself to support, may with propriety be carried to a much greater height than any other species of build ing. These principles are all that seem to regulate the external proportions of simple buildings, and all of them obviously depend upon fitness.
Having discussed what relates to the proportion or fit ness of the general outlines of buildings, Mr Alison pro ceeds to treat of the orders of architecture, and to show, that their proportions, instead of being intrinsically beau tiful of themselves, are regulated by the general princi ples which have been established in this essay, and de rive their merit solely from the expressions of fitness for their several purposes. But as this important part of the discussion overthrows established opinions, which have a peculiarly strong possession of the minds of all those who have paid attention to or are engaged in archi tectural pursuits, we shall quote the precise words of the author : " It is not in such (simple) buildings, accordingly, that any very accurate external proportions have ever been settled. This is peculiar to N‘ hat are called the orders of architecture, in which the whole genius of the art has been displayed, and in which the proportions are settled with a certainty, so absolute, as to forbid almost the at tempt at innovation.
66 There are generally said to be five orders of archi tecture, viz. the Tuscan, the Doric, the Ionic, the Co rinthian, and the Composite. These are, however, pro perly only four, and some writers have farther reduced them to three. What constitutes an order, is its pro portions, not its ornaments. The Composite having the same proportions as the Corinthian, though very different in respect to its ornaments, is properly, therefore, con sidered a corrupted Corinthian.
" Every order consists of three great parts, or divi sions ; the base, the column, and the entablature ; and the governing proportions relate to this division. The whole of them compose the wall, or what answers to the wall of a common building, and supports the roof.
64 There is one great difference, however, to be observ ed between a common wall, and that assemblage of parts which constitute an order. A common wall is intended to support a roof, and derives its proportions, in a great measure, from this destination. To an order, the consi deration of a roof is unnecessary ; it is generally so con trived as not to appear : the weight which is supported, or appears to be supported, in an order, is the entabla ture. The fitness of a wall consists in appearing adequate to the support of the roof. The fitness of an order, or of the proportions of an order, it should seem also from ana logy reasonable to conclude, consists in their appearing adequate to the support of the entablature, or the weight which is imposed on them.
46 That this is really the case, and that it is from their being expressive to us of this fitness, that the proportions of these different orders appear beautiful, may perhaps seem probable from the following observations : " 1. The appearance of these proportions themselves seems very naturally to lead us to this conclusion. In all the orders, the fitness of the parts to the support, of the peculiar weight, or appearance of weight of entablature, is apparent to every person, and constitutes an undoubt ed part of the pleasure we receive from them. In the Tuscan, where the entablature is heavier than in the rest, the column and base are proportionably stronger. In the Corinthian, when the entablature is lightest, the column and base are proportionably slighter. In the Doric and Ionic, which are between these extremes, the forms of the column and base are, in the same manner, proportioned to the reciprocal weights of their entabla tures; being neither so strong as the one, nor so slight as the other. If the beauty of such proportions is alto gether independent of fitness, and derived from the im mediate constitution' of our nature, it is difficult to ac count for this coincidence ; and as the beauty of fitness, in these several cases, is universally allowed, it is alto gether unphilosophical to substitute other causes of the same effect, until the insufficiency of this is clearly point ed out.