MILITARY ENGINES. 113 



breast- work, the battlements of which formed embrasures for the projectiles 

 then in use, some of which we shall again refer to hereafter. At the siege 

 of Jerusalem by the Crusaders, the most important results were obtained by 

 means of these towers. Godfrey of Bouillon, as William of Tyre relates, 

 had three great movable towers built, whose front side, from the first story 

 up, was double, so that when the tower reached the outer edge of the ditch, 

 this front side formed a drawbridge long enough to reach across, was let 

 down by ropes, fell on the hostile wall, and by its great width enabled 

 a strong force to throw themselves upon the defenders of the rampart, 

 supported by those stationed upon the platform of the tower (pi. S4,Jlg. 24). 

 Only by means of these three towers Jerusalem fell, on the 15th July, 1099, 

 after a siege of one month, into the hands of the Crusaders. 



d. Implements of Defence. As soon as it became requisite to carry on 

 works of long duration, entrenchments, &c., within the range of the enemy's 

 missiles, means were sought to protect the laborers while thus employed. 

 The simplest defensive implements here were blinds, walls about six or 

 eight feet high and fifteen or twenty feet long. These screens were either 

 straight or round. The straight ones (pi. 33, fig. 17) consisted of two 

 frames of timber-work, between which bundles of twigs (fascines) or sand 

 bags were placed ; they were supported by trestles on rollers, and moved 

 by men or by horses according to their size, backwards or forwards as the 

 workmen receded or advanced. The round blinds (fig. 18) consisted also 

 of frames, but with curved foot and cap pieces, and the field of the frame 

 was set with thick planks or logs, in front of which, fenders of .hide 

 stufted with wool or sand were hung, rendering the enemy's missiles inef- 

 fectual. These blinds were on rollers also, so that they might be moved 

 when necessary. 



To protect the workmen in wall-breaching, so that they should not be 

 crushed by stones and beams hurled down upon them, the implements called 

 tortoises were employed, structures which were covered at the sides and 

 top. For the rolling ram these structures were simple sheds (fig. 15) stand- 

 ing on rollers, and moved by the persons inside up against the wall ; then 

 the frame for the ram was laid upon the floor of this shed. The tortoise 

 for the swinging ram, however, was made much higher in front (fig. 16), 

 as it had to protect also the lofty frame from which the ram was suspended. 

 On the front side, and particularly on the roof, the tortoise was always hung 

 with skins and hair covers, and th-ese covers wetted as often as possible, to 

 render ineffectual the enemy's eflforts to set the machines on fire. The 

 troops themselves, in the assault, formed also a species of tortoise, for pro- 

 tection against the stones and other missiles hurled from above (pi 35, fig. 11) 

 by holding their great shields over their heads, in such manner that the 

 edges overlapped each other some six or eight inches or more, thus forming 

 a kind of storm-roof, of such strength, indeed., that often a second column, 

 and sometimes a third, was supported upon it, and thus the wall or a high- 

 lying breach was mounted. Such tortoises were used also where the ram 

 was applied in its simplest form (fig. 8), hung merely from a simple frame 

 which leaned against the wall. 



689 



