plinth, or base, a superficies of wall, and a coping.  We will mark the thickening at the base by a moulding, which will give a few horizontal lines (at B), and the coping in the same way.  The moulding of the coping must also be so designed as to have a hollow throating, which will act as a drip, to keep the rain from running round the under side of the coping and down the wall.  We may then break up the superficies by inserting a band of single ornament in one course of this portion of the wall—­not half way, for to divide any portion of a building into mere “halves” has usually a weak and monotonous effect, but about two thirds of the distance from the base line; and this band of ornament not only breaks up the plain surface a little, but also, by carrying another horizontal line along the wall, emphasizes its horizontality.  Always emphasize that which is the essential characteristic of your structure.  A wall of this kind is essentially a long horizontal boundary.  Emphasize its length and horizontality.

   [Footnote 2:  The dark shaded portion in this and the next two
   diagrams show the “section” of the wall as seen if we cut it
   through and look at it endwise.]

If we are millionaires, and can afford to spend a great deal on a wall, we may not only (Fig. 3) carry further the treatment of the coping and base, by giving them ornamental adjuncts as well as mouldings, but we might treat the whole wall superficies as a space for surface carving, not mechanically repeated, but with continual variation of every portion, so as to render our wall a matter of interest and beauty while retaining all its usefulness as a boundary, observing that such surface ornament should be designed so as to fulfill a double object:  1, to give general relief to the surface of the wall; 2, to afford matter of interest to the eye on close inspection and in detail.

That is the double function of nearly all architectural ornament.  It is, in the first place, to aid the general expression and balance of the building, and give point and emphasis where needed; and, in the second place, to furnish something to the eye for study on its own account when viewed more closely.

[Illustration:  Figs. 4 through 9]

We will take another typical and simple erection, a stone pillar to support the ends of two lintels or beams.  This may be simply a long squared piece set on end (Fig. 4), and will perform its constructive functions perfectly well in that form; but it is not only absolutely expressionless, but is in one sense clumsy and inconvenient, as taking up more space than need be, presenting an unwieldy-looking mass when viewed at an angle, and shutting out a good deal of light (if that happen to be a matter of practical consequence in the case).  Cutting off the angles (Fig. 5) does not weaken it much, and renders it much less unwieldy-looking, besides giving it a certain degree of verticality of expression, and rendering