94 THE STONES OF VENICE CONSTRUCTION

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. 5; 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.

§ 6. 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 honour and ornament. It has been esteemed so by almost all builders, and has been lavishly decorated in modes here-after 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 farther, 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 honour of the wall,

[Version 0.04: March 2008]