The manner in which the capital is allied to the shaft below, and the architrave above shows changes of the same kind.
The first duty of the capital is to oppose a firm and individual contour to the monotony of the shaft. The constructor has to determine a point in the length of the latter where it shall cease to be, where its gradual diminution in section, a diminution which could not be prolonged to the architrave without compromising the safety of the building, shall be arrested. The natural office of the capital would seem to be to call attention to this point. The architect, therefore, gives it a diameter greater than that of the shaft at the point where they meet. This salience restores to the column the material which it has lost; it completes it, and determines its proportion, so that it is no longer capable of either increase or diminution.
Again, when the salience is but the preparation for a greater development above, it seems to add to the solidity of the edifice by receiving the architrave on a far larger surface than the shaft could offer. The support seems to enlarge itself, the better to embrace the entablature.
The two requirements which the capital has to fulfil may, then, be thus summarized: in the first place, it has to mark the point where the upward movement of the lines comes to an end; and, secondly, it has to make, or to seem to make, the column better fitted to play its part as a support. Its functions are dual in principle; it has to satisfy the æsthetic desires of the eye, and the constructive requirements of the material. The latter office may be more apparent than real, but, in architecture, what seems to be necessary is so.
The Greek capital, in all its forms, thoroughly fulfils these double conditions, while that of Egypt satisfies them in a very imperfect manner. Let us take the ancient polygonal column as an example. The feeble tablet which crowns its shaft neither opposes itself frankly to the upright lines below it, nor, in the absence of an echinus, is it happily allied with the shaft. It gives, however, a greater appearance of constructive repose to the architrave than the latter would have without it.
In the column which terminates in a lotus-bud the capital is of more importance, but the contrast between it and the shaft is often very slightly marked. At Luxor and Karnak the smooth capital seems to be nothing more than an accident, a gentle swelling in the upper part of the cone; besides which it really plays no part in the construction, as the surface of the abacus above it is no greater than a horizontal section through the highest and most slender part of the shaft.
Fig. 97.—The Nymphæa Nelumbo; from the Description de l'Égypte; Hist. Naturelle, pl. 61.
Of all the Egyptian capitals, that which seems the happiest in conception is the campaniform. This capital, far from being folded back upon itself, throws out a fine and bold curve beyond the shaft. But we are surprised and even distressed to find that the surface thus obtained is not employed for the support of the architrave, which is carried by a comparatively small cubic abacus, which rests upon the centre of the capital. At Karnak and Medinet-Abou this abacus is not so absurdly high as it afterwards became in the Ptolemaic period,[107] but yet its effect is singular rather than pleasant. We feel inclined to wonder why this fine calyx of stone should have been constructed if its borders were to remain idle. It is like a phrase commenced but never finished. Without this fault the composition, of which it forms a part, would be worthy, both in proportion and in decoration, of being placed side by side with the most perfect of the Greek columns.