Page:Vitruvius the Ten Books on Architecture.djvu/123

93, belongs to its echinus. The projection of the echinus beyond the fillet of the abacus should be equal to the size of the eye. The projection of the bands of the cushions should be thus obtained: place one leg of a pair of compasses in the centre of the capital and open out the other to the edge of the echinus; bring this leg round and it will touch the outer edge of the bands. The axes of the volutes should not be thicker than the size of the eye, and the volutes themselves should be channelled out to a depth which is one twelfth of their height. These will be the symmetrical pro­portions for capitals of columns twenty-five feet high and less. For higher columns the other proportions will be the same, but the length and breadth of the abacus will be the thickness of the lower diameter of a column plus one ninth part thereof; thus, just as the higher the column the less the diminution, so the pro­jection of its capital is proportionately increased and its breadth is correspondingly enlarged.

8. With regard to the method of describing volutes, at the end of the book a figure will be subjoined and a calculation showing how they may be described so that their spirals may be true to the compass.

The capitals having been finished and set up in due propor­tion to the columns (not exactly level on the columns, however, but with the same measured adjustment, so that in the upper members there may be an increase corresponding to that which was made in the stylobates), the rule for the architraves is to be as follows. If the columns are at least twelve feet and not more than fifteen feet high, let the height of the architrave be equal to half the thickness of a column at the bottom. If they are from fifteen feet to twenty, let the height of a column be measured off into thirteen parts, and let one of these be the height of the archi­trave. If they are from twenty to twenty-five feet, let this height be divided into twelve and one half parts, and let one of them form the height of the architrave. If they are from twenty-five feet to thirty, let it be divided into twelve parts, and let one of