The clay used for the purpose was by no means uniform either as regards its colour, or as regards its quality. Sometimes it is of a light yellow colour, sometimes it is almost black, while the clay from which other bricks are made is of a reddish hue. Those made of light yellow clay are the best from the point of view of durability. The bricks further vary both in size and shape according to the period to which they belong, so that it is often possible to provisionally assign a date to a building or the remains of a building by an examination of the style of brick employed. The type of brick characteristic of the early periods of Sumerian history is that known as the plano-convex[48] type; thus the kiln-burnt bricks of which the storehouse of Ur-Ninâ, the first king of Lagash, was composed, are oblong and plano-convex, while each of them also bears the impression of a thumb-mark on the convex side.
But a yet earlier form of brick[49] was found in the building underneath Ur-Ninâ’s storehouse: the bricks of which this building was composed were indeed plano-convex like those of Ur-Ninâ, but they were smaller, had no thumb- or finger-marks and were also unfortunately uninscribed.
At Muḳeyyer (Ur) Taylor came across a pavement made of plano-convex bricks, the antiquity of which was attested alike by the appearance of this type of brick and also by the depth below the surface at which the platform was found. This excavator discovered similar bricks at Abû Shahrein (Eridu), a further corroboration of the traditional antiquity of Ea’s once famous city. The excavations at other early sites have also yielded the same results; at Fâra (Shuruppak) the traditional scene of the Deluge, as well as at Yôkha, Bismâya, and in the pre-Sargonic strata at Nippur, the same style of bricks has been found.
But with the expansion of the Semites, culminating in the establishment of the empire of Shar-Gâni-sharri and his son Narâm-Sin, the comparatively small, oblong and plano-convex brick fell into disuse, and gave way to a large square brick. Immediately beneath the crude-brick platform of Ur-Engur (circ. 2400 B.C.) at Nippur, part of the earlier work of Narâm-Sin and Shar-Gâni-sharri was uncovered, the bricks used being no longer plano-convex and oblong, but flat and square, and measuring 20 x 20 x 3-1/2 inches; they are made of clay mixed with straw, and are at the same time well-dried and very hard; this type of brick was employed in all the buildings of these two kings.
The next period in the history of Babylonian brick-making is that belonging to the times of the second dynasty of Lagash and the first dynasty of Ur (i.e. circ. 2450 B.C.). The type of brick characteristic of this age resembles that of the preceding in regard to shape but not in regard to size. The bricks of Ur-Engur, king of Ur, and of Gudea, the most renowned ruler of the second dynasty of Lagash (circ. 2450 B.C.) are square like those of their Semitic predecessors, Shar-Gâni-sharri and Narâm-Sin, but very much smaller, measuring a little over 12 x 12 inches, and this small square brick remained in use, with occasional slight variations, till the close of Mesopotamian history. The transition from the large brick used by the kings of Agade to the small brick in question was doubtless effected only gradually, for the bricks of Ur-bau, ruler of Lagash some time before Gudea, are larger than those of the latter king, but after the time of Gudea and Ur-Engur, the shape and size of the bricks became more or less stereotyped. The bricks of Ur-Engur himself vary somewhat from those of Gudea, thus the solid mass underlying the temple-tower at Nippur, which was constructed by Ur-Engur, is composed of bricks measuring only 9 × 6 × 3 inches, the arms of the causeway on the other hand are built of larger bricks measuring 14 × 14 × 6 inches. Kiln-burnt bricks were always used for the important parts of the building in Babylonia, the crude sun-dried bricks which as a rule formed the core of the terraced platforms, being revetted with a wall of burnt brick, or sometimes, in the case of Assyria with a supporting wall of stone. The reason of course for this lay in the inability of sun-dried bricks to resist damp, and their corresponding tendency to disintegrate. The bricks were as a rule carried on to the ground as soon as they were fairly dry and firm, and were laid while still soft.
Generally speaking the bricks bear the name of the king who caused the structure to be made, thus the majority of the bricks of Nebuchadnezzar, king of Babylon (604-561 B.C.) are inscribed:—“Nebuchadnezzar, King of Babylon, restorer of the pyramid and tower, eldest son of Nabopolassar, King of Babylon, am I.” It is interesting to note that though the tiles on the western side of Nebuchadnezzar’s palace at Babylon bear the ordinary stamp of that king, those on the eastern side are stamped with a lion and an Aramaic inscription. Koldewey indeed says that there is no doubt that this part of the building was also erected by Nebuchadnezzar, as wall-tiles bearing the regular palace-inscription of the king have been found there. Prof. Euting however, from the forms of the Aramaic characters, would assign these Aramaic-inscribed bricks to the middle of the seventh century, i.e. about 650 B.C. None of the bricks found on the Kasr mound bear the stamp of any Assyrian kings, the latter apparently only having left their marks on the floor-bricks of E-sagila, the temple of Marduk. The characters were generally impressed with a stamp, though on both Assyrian and Babylonian bricks the inscription was sometimes engraved by hand. The stamps used were made of terra-cotta; a well-preserved specimen of a terra-cotta brick-stamp is that of Narâm-Sin referred to above (cf. Fig. [4]), while a terra-cotta brick-stamp of Shar-Gâni-sharri, the father of Narâm-Sin, was discovered at Nippur, and one of the minor results of the expedition to Bismâya, directed by Harper, was the discovery of a number of clay brick-stamps. Many Assyrian and Babylonian bricks are glazed or enamelled and coloured in the most ornate fashion, and with the most striking pictures and designs, but an examination of these will naturally find its place in the chapter devoted to “Painting.”
Sometimes the architects of Babylonia contrived to adapt the clay employed in their building operations to decorative devices. Such was the case at Warka (Erech) where Loftus discovered a wall some thirty feet long, composed entirely of clay cones fixed in a cement made of mud and straw, and laid horizontally with their bases outwards. Some of these cones had been coloured red or black and were arranged to form various geometrical designs. They were sometimes inscribed, sometimes not. But clay cones were apparently not the only kind of cone used for architectural decoration, for in the course of his excavations at Abû Shahrein, Taylor[50] discovered cones of limestone and marble, some of which had a “rim round the edge filled with copper”; these cones vary from four to ten inches in length, their diameter measuring from one to three inches.
MORTAR
The layers and courses of clay bricks of which the buildings in Mesopotamia were for the most part composed, were cemented together by mud in the earliest times; this clay-mud is generally distinguishable from the bricks which it unites by the difference of its colour. Mud-mortar has been found on some of the earliest sites and in some of the most ancient buildings, while in Assyria it appears to have been the regular form of cement used at all times. In the city of Babylon, strange to say, clay mortar appears to have been used instead of lime or asphalt in the late buildings of Sassanidian times. This mud-mortar consisted of clay mixed with water and perhaps a little straw, as was the case in the cone-wall at Warka,[51] while sometimes reeds embedded in clay were laid between the bricks, as was the case at both Warka and Hammam, but at an extremely remote period the Babylonian architect began to avail himself of the rich supply of bitumen gratuitously yielded by the soil of his native land, for the purpose in question.