The cornice is as indispensable a termination of the wall as the capital is of a pillar; and suggests not only an appropriate support for the roof, but eaves to throw the rain off the wall. The same is true with regard to pediments or caps over windows: they suggest a means of protecting an opening from the wet; and porches over doorways are equally obvious contrivances. Everything, in short, which is actually constructive, or which suggests what was or may be a constructive expedient, is a legitimate object of decoration, and affords the architect unlimited scope for the display of taste and skill, without going out of his way to seek it. The difficulty in applying ornaments borrowed from other styles is, that although they all suggest construction, it is not _the_ construction of the buildings to which they are applied. To use Pugin’s clever antithesis, “they are constructed ornament, not ornamented construction,” and as such can never satisfy the mind. However beautiful in themselves, they are out of place, there is no real or apparent use for their being there; and, in an art so essentially founded on utilitarian principles and common sense as architecture is, any offence against constructive propriety is utterly intolerable. The other class, or decorative ornaments, are forms invented for the purpose, either mere lithic forms, or copied from the vegetable kingdom, and applied so as to give elegance or brilliancy to the constructive decoration just described. The first and most obvious of these are mere mouldings, known to architects as Scotias, Cavettos, Ogees, Toruses, Rolls, &c.—curves which, used in various proportions either horizontally or vertically, produce when artistically combined, the most pleasing effect. In conjunction with these, it is usual to employ a purely conventional class of ornament, such as frets, scrolls, or those known as the bead and reel, or egg and dart mouldings; or in Gothic architecture the billet or dog-tooth or all the thousand and one forms that were invented during the Middle Ages. In certain styles of art, vegetable forms are employed even more frequently than those last described. Among these, perhaps the most beautiful and perfect ever invented was that known as the honeysuckle ornament, which the Greeks borrowed from the Assyrians, but made so peculiarly their own. It has all the conventional character of a purely lithic, with all the grace of a vegetable form; and, as used with the Ionic order, is more nearly perfect than any other known.