I. We have lastly to consider the close of the wall’s existence, or its cornice. It was above stated, that a cornice has one of two offices: if the wall have nothing to carry, the cornice is its roof, and defends it from the weather; if there is weight to be carried above the wall, the cornice is its hand, and is expanded to carry the said weight.
There are several ways of roofing or protecting independent walls, according to the means nearest at hand: sometimes the wall has a true roof all to itself; sometimes it terminates in a small gabled ridge, made of bricks set slanting, as constantly in the suburbs of London; or of hewn stone, in stronger work; or in a single sloping face, inclined to the outside. We need not trouble ourselves at present about these small roofings, which are merely the diminutions of large ones; but we must examine the important and constant member of the wall structure, which prepares it either for these small roofs or for weights above, and is its true cornice.
§ II. The reader will, perhaps, as heretofore, be kind enough to think for himself, how, having carried up his wall veil as high as it may be needed, he will set about protecting it from weather, or preparing it for weight. Let him imagine the top of the unfinished wall, as it would be seen from above with all the joints, perhaps uncemented, or imperfectly filled up with cement, open to the sky; and small broken materials filling gaps between large ones, and leaving cavities ready for the rain to soak into, and loosen and dissolve the cement, and split, as it froze, the whole to pieces. I am much mistaken if his first impulse would not be to take a great flat stone and lay it on the top; or rather a series of such, side by side, projecting well over the edge of the wall veil. If, also, he proposed to lay a weight (as, for instance, the end of a beam) on the wall, he would feel at once that the pressure of this beam on, or rather among, the small stones of the wall veil, might very possibly dislodge or disarrange some of them; and the first impulse would be, in this case, also to lay a large flat stone on the top of all to receive the beam, or any other weight, and distribute it equally among the small stones below, as at a, Fig. IV.
Fig. IV.
§ III. We must therefore have our flat stone in either case; and let b, Fig. IV., be the section or side of it, as it is set across the wall. Now, evidently, if by any chance this weight happen to be thrown more on the edges of this stone than the centre, there will be a chance of these edges breaking off. Had we not better, therefore, put another stone, sloped off to the wall, beneath the projecting one, as at c. But now our cornice looks somewhat too heavy for the wall; and as the upper stone is evidently of needless thickness, we will thin it somewhat, and we have the form d. Now observe: the lower or bevelled stone here at d corresponds to d in the base (Fig. II., page 59). That was the foot of the wall; this is its hand. And the top stone here, which is a constant member of cornices, corresponds to the under stone c, in Fig. II., which is a constant member of bases. The reader has no idea at present of the enormous importance of these members; but as we shall have to refer to them perpetually, I must ask him to compare them, and fix their relations well in his mind: and, for convenience, I shall call the bevelled or sloping stone, X, and the upright edged stone, Y. The reader may remember easily which is which; for X is an intersection of two slopes, and may therefore properly mean either of the two sloping stones; and Y is a figure with a perpendicular line and two slopes, and may therefore fitly stand for the upright stone in relation to each of the sloping ones; and as we shall have to say much more about cornices than about bases, let X and Y stand for the stones of the cornice, and Xb and Yb for those of the base, when distinction is needed.
§ IV. Now the form at d, Fig. IV., is the great root and primal type of all cornices whatsoever. In order to see what forms may be developed from it, let us take its profile a little larger—a, Fig. V., with X and Y duly marked. Now this form, being the root of all cornices, may either have to finish the wall and so keep off rain; or, as so often stated, to carry weight. If the former, it is evident that, in its present profile, the rain will run back down the slope of X; and if the latter, that the sharp angle or edge of X, at k, may be a little too weak for its work, and run a chance of giving way. To avoid the evil in the first case, suppose we hollow the slope of X inwards, as at b; and to avoid it in the second case, suppose we strengthen X by letting it bulge outwards, as at c.
Fig. V.
§ V. These (b and c) are the profiles of two vast families of cornices, springing from the same root, which, with a third arising from their combination (owing its origin to æsthetic considerations, and inclining sometimes to the one, sometimes to the other), have been employed, each on its third part of the architecture of the whole world throughout all ages, and must continue to be so employed through such time as is yet to come. We do not at present speak of the third or combined group; but the relation of the two main branches to each other, and to the line of origin, is given at e, Fig. V.; where the dotted lines are the representatives of the two families, and the straight line of the root. The slope of this right line, as well as the nature of the curves, here drawn as segments of circles, we leave undetermined: the slope, as well as the proportion of the depths of X and Y to each other, vary according to the weight to be carried, the strength of the stone, the size of the cornice, and a thousand other accidents; and the nature of the curves according to æsthetic laws. It is in these infinite fields that the invention of the architect is permitted to expatiate, but not in the alteration of primitive forms.
§ VI. But to proceed. It will doubtless appear to the reader, that, even allowing for some of these permissible variations in the curve or slope of X, neither the form at b, nor any approximation to that form, would be sufficiently undercut to keep the rain from running back upon it. This is true; but we have to consider that the cornice, as the close of the wall’s life, is of all its features that which is best fitted for honor and ornament. It has been esteemed so by almost all builders, and has been lavishly decorated in modes hereafter to be considered. But it is evident that, as it is high above the eye, the fittest place to receive the decoration is the slope of X, which is inclined towards the spectator; and if we cut away or hollow out this slope more than we have done at b, all decoration will be hid in the shadow. If, therefore, the climate be fine, and rain of long continuance not to be dreaded, we shall not hollow the stone X further, adopting the curve at b merely as the most protective in our power. But if the climate be one in which rain is frequent and dangerous, as in alternations with frost, we may be compelled to consider the cornice in a character distinctly protective, and to hollow out X farther, so as to enable it thoroughly to accomplish its purpose. A cornice thus treated loses its character as the crown or honor of the wall, takes the office of its protector, and is called a DRIPSTONE. The dripstone is naturally the attribute of Northern buildings, and therefore especially of Gothic architecture; the true cornice is the attribute of Southern buildings, and therefore of Greek and Italian architecture; and it is one of their peculiar beauties, and eminent features of superiority.
§ VII. Before passing to the dripstone, however, let us examine a little farther into the nature of the true cornice. We cannot, indeed, render either of the forms b or c, Fig. V., perfectly protective from rain, but we can help them a little in their duty by a slight advance of their upper ledge. This, with the form b, we can best manage by cutting off the sharp upper point of its curve, which is evidently weak and useless; and we shall have the form f. By a slight advance of the upper stone c, we shall have the parallel form g.
These two cornices, f and g, are characteristic of early Byzantine work, and are found on all the most lovely examples of it in Venice. The type a is rarer, but occurs pure in the most exquisite piece of composition in Venice—the northern portico of St. Mark’s;
