Fig. 113.—Fragment from Babylon. British Museum. Height 11 inches, width 9 inches.
A study of those reliefs in which nothing but purely ornamental motives are treated, leads us to exactly the same conclusion. Take for instance the great bronze threshold from Borsippa, of which we have already spoken; the rosettes placed at intervals along its tread are identical with those encountered in such numbers in Assyria.
In the extreme rarity of stone in his part of the world the Chaldæan architect seems to have practically reserved it for isolated statues, for votive bas-reliefs, for objects of an iconic or religious character, but nevertheless, we have sufficient evidence to prove that such decorative sculpture as found a place in the Chaldæan buildings, did not sensibly differ from that to which Assyria has accustomed us.
From all that we have said as to the distribution of stone, it will be understood that we must turn to Assyria to obtain a clear idea of the measures by which buildings of crude brick were rendered more sightly by ornament in the harder material. We can hardly imagine an Assyrian palace without those series of bas-reliefs which now line the walls of our museums much in the same fashion as they covered those of Sargon's and Sennacherib's palaces, and yet it is unlikely that in the beginning the Assyrian palaces had these carved walls. The casing of stone and alabaster must have been originally employed for more utilitarian purposes—to hide the grey and friable material within, to protect it from damage, and to offer a surface to the eye which should at least be inoffensive. The upper parts of the walls would be covered with a coat of stucco, which could be renewed whenever necessary, but for the lower part, for all that was within reach of the crowds that frequented the public halls of the seraglio, who passed through its gates or those of the city itself, some more efficient protection would be required. The constructor was thus led to encase the lower parts of his walls in a cuirass of stone imposed upon their brick cores. The slabs of which he made use for this purpose varied between three and ten feet in height, and between six and fifteen in width. Their average thickness was about eight inches.
The way in which these slabs were fixed is hardly worthy of such clever builders, and, in fact, the Assyrians seem to have never succeeded in mastering the difficulties inherent in the association of two heterogeneous materials. The slabs were of gypsum or limestone, the wall of pisé, materials which are not to be easily combined. The Assyrians contented themselves with simply placing the one against the other. No trace of any tie is to be found. A "tooth" has been given to the inner faces of the slabs by seaming them in every direction with the chisel, and, perhaps, some plastic substance may at the last moment have been introduced between them and the soft clay, but no trace of any other contrivance for keeping the two materials together has been found. After the general mass of the building—its clay walls and vaults—were complete, a different class of workmen was brought in to line its chambers and complete their decoration. The crude brick would by that time have become dry, and no longer in a condition to adapt itself to the roughnesses of the alabaster slabs. The liquid clay, like that of an earthenware "body," wets and softens the surface of the brick while it enters into every hollow of the stone and so allies the one with the other. We recommend this conjecture to those who may undertake any future excavation in Assyria. It lies with them to confirm or refute it.
However this may have been, the constructor made use of more than one method of giving greater solidity to his walls as a whole. His slabs were not only let into each other at the angles, in some chambers there were squared angle pieces of a diameter great enough to allow them to sink more deeply into the crude brick behind, and thus to offer steady points of support in each corner. Finally the separate slabs were held together at the top by leaden dovetails like the metal clamps used to attach coping stones to each other.
Such precautions were rendered comparatively useless by the fact that the whole work was faulty at the base. Halls and chambers had no solid foundation or pavement, so that the heavy slabs of their decoration rested upon a shifting soil, quite incapable of carrying them without flinching. In many places they sank some inches into the ground, the soft earth behind pushing them forward, and in their fall the row to which they belonged was inevitably involved. The excavators have again and again found whole lines of bas-reliefs that appeared to have fallen together. Such an accident is a thing for posterity to rejoice over. Prone upon a soft and yielding soil the works of the sculptor are better protected than when standing erect, their upper parts clear, perhaps, of the ruin that covers their feet, and exposed to the weather at least, and, too often, to the brutality of an ignorant population.
Such defects are sufficient to prove that these slabs were never meant to carry any great weight; far from affording a support to the wall behind, they required one to help them in maintaining their own equilibrium. On the other hand they protected it, as we have said above, from too rapid deterioration.
At Khorsabad this stone casing is in very bad condition at many points, in the halls and passages of the outbuildings and in the courtyards adjoining the city gates for instance.[332] There the stones are only smoothed down, and their obvious purpose is merely to protect the crude brick within. The purely architectural origin of this system of casing is thus clearly shown.
But the presence of these slabs set upright against the wall offered a temptation to the ambitious architect that he was not likely to resist. The limestone and alabaster of which they were composed afforded both a kindly surface for the chisel, and a certain guarantee of duration for the forms it struck out. In every Assyrian palace we may see that the king, its builder, had a double object in view, the glorification of the gods, and the transmission to posterity of his own image and the memory of his reign. To these ends the architect called in the sculptor, under whose hands the rudely dressed slabs took the historic forms with which we are familiar.