[Illustration: FIG. 55.--Rudimentary Form of Capital.] The two capitals in the loggia by the baptistery furnish a well-defined variety of the impost capital. The square at the top is here wrought into curves recalling the antique abacus. These are gathered together into the circle of the necking in a beautiful convex form which may be called the Melon type II., see Fig. 54. We give in Fig. 50 an outline of the whole column of the great order in the interior of the church, and in Fig. 56 a diagram of the blocking out of the capital. The columns here and throughout the great church being monoliths of fine material, the supporting area is very small compared to the area of the arch imposts, which are of brick sheeted with marble. It will be seen that the projection is just that required by the impost, which springs directly from the outside edge. [Illustration: FIG. 56.--Rudimentary Form of Capital. Type III.] The great capitals of S. Sophia are remarkable examples of the evolution of beautiful forms on the mason’s banker; the workman _finding form_ in the stone block by the application of practical methods. The lower half of the capital is circular like the shaft, rising in a slightly swelling curve of a bowl; the upper part is square like the impost. The basis of form is that of a bowl with a tile placed above it, and is thus that of the Greek Doric. This type III. in which the circle does not pass by transition into the square impost, but changes abruptly, we may call the bowl and tile capital. At S. Sophia the surface of the form obtained as shown in the figure is wrought into crisp acanthus and palm foliage; and is in many places, especially at the tips of the leafage and behind the monograms, entirely undercut. The cutting being so sharp, and the shadows so deep, while at the same time the general form with its broad gradation of light and shade is so little modified by surface modelling, the effect is almost that of inlaying black on white. The capitals of the columns standing in the aisles, and those of the first floor ranged against the central area, are similar to the great order, but simplified and reduced. The columns of the aisles on the first floor have block capitals, with small volutes below; Fig. 57 will make the elementary form clear. This type IV. is really a Byzantine Ionic. The dual columns of west gallery have a capital in common, which is a variation of these, and the capitals of atrium were also similar. One capital of the north gallery is entirely different from all the rest, the block, not being carved all over continuously, is broken up into several horizontal lines of ornament. For the capitals of the square pillars of ground floor, and others to the windows, we must refer to Salzenberg; they are all of the simple block form delicately sculptured.