The proportions of the upper order are obtained by making the lower diameter of the upper tier of columns or pilasters equal to the upper diameter of those
No. 172. Order above Order.
of the supporting order, and an effect of continuous tapering is produced.
It is usual to place above the entablature of the lower order a plinth on which the bases of the upper columns rest. The height of the plinth is regulated by the point of view, as its purpose is to display the bases of the imposed order above the projecting cornice. Generally this height will be about half a diameter.
In many historical examples the upper columns are placed on pedestals, but this treatment, although useful when a balcony is desired, is not to be recommended as the extra width and projection which the use of the pedestal entails, gives an appearance of undue weight to be borne by the supporting columns. If balconies are necessary they may terminate with their own pedestals, which can be kept clear of the columns and should not exceed them in projection.
The Pilaster
It may be as well to deal here with the treatment of pilasters, which may be defined as columns in bas-relief. Their projection may vary from one-half to about one-sixth their face width, though in antique examples it is sometimes much less than this. In the pilasters of the Pantheon at Rome it is one-tenth.