‹‹‹ Vitr. 5.9.1 | Table of Contents | Vitr. 5.9.3 ›››
2which ought to be constructed double, with their exterior columns of the Doric order, whose architraves, and cornices are to be wrought after the Doric method. Their width is to be thus proportioned: the height of the exterior columns is equal to the distance from the lower part of the shaft of the exterior columns to that of those in the middle, and from them to the walls which surround the walks of the portico is an equal distance. The middle range of columns is one fifth part higher than the exterior range; and is of the Ionic or Corinthian order.
2The approved way of building them requires that they should be double, and have Doric columns on the outside, with the architraves and their ornaments finished according to the law of modular proportion. The approved depth for them requires that the depth, from the lower part of the outermost columns to the columns in the middle, and from the middle columns to the wall enclosing the walk under the colonnade, should be equal to the height of the outer columns. Let the middle columns be one fifth higher than the outer columns, and designed in the Ionic or Corinthian style.