Military Arciiitkcture. 49 which faces north-west there is a long diagonal buttress, by the use of which the engineer or architect at once economized material and protected a weak part of his structure in a most efficient manner. The salient angles of the enceinte were pro- tected by double towers, very well disposed so as to command the ditch. A symmetrical regularity is not to be found here any more than in the funerary and religious structures of Egypt. The curtain wall between two of the towers on the southern face is broken up into small buttresses of various degrees of salience, instead of being planned on a straight line like the rest. When the fortress was prepared for defence the parapets may have been furnished w^ith wooden structures acting as machicola- tions, whence the besieged could cast javehns and stones and shoot arrows at an enemy attempting to scale or batter the walls. A bas-relief at Thebes which represents the siege of a fortress seems to indicate that the parapets were crowned by wooden erections of some kind (Fig. 32).^ The walls were surrounded by a ditch, which was from 95 to 125 feet wide. We cannot now tell what its depth may have been, but it appears to have been paved. The counterscarp and certain parts of the scarp were faced with stone, caretully polished, and fixed so as to augment the difficulty of approach. Moreover, the crown of the glacis and the wide glacis itself were also reveted with stone. All this formed a first line of defence, which had to be destroyed before the assailants could reach the place itself with their machines. The external line of the ditch does not follow all the irregularities of the enceinte, its trace is the same as that of the curtain wall, exclusive of the towers or buttresses. The clear width from the face of the latter is about sixty-four feet. Neither ditch nor glacis exist on the eastern face, where the rapids of the Nile render them unnecessary. We must not forget to draw attention to the curious way in which the body of the fort is constructed. It is composed of crude bricks transfixed horizontally, and at rather narrow interv^als, by pieces of wood. The situation of these beams may be easily recognized as they have decayed and left channels in the brick- work. That the holes with which the walls are pierced at regular distances (see Fig. 30) were thus caused, is beyond doubt, especially ^ Both the plate in the Description de F Egypte {Ant. vol. ii. pi. 31), and that in Lepsius (part iii.pl. 166), suggest this interpretation. VOL. n. H
