Père Daniel, in his _Histoire de la Milice Françoise_, writes: ‘The great object of the French engineers was to make siege engines of sufficient strength to project stones large enough to crush in the roofs of houses and break down the walls.’ This author continues: ‘The French engineers were so successful and cast stones of such enormous size that their missiles even penetrated the vaults and floors of the most solidly built houses.’[34] [34] These engines would also be trebuchets. [Page 39] The effects of the balista on the defenders of a town were in no degree inferior to those of the catapult. The missile of the balista consisted of a huge metal-tipped wooden bolt which, although of far less weight than the great ball of stone cast by a catapult or the far larger one thrown by a trebuchet, was able to penetrate roofs and cause great destruction in ranks of soldiers. Cæsar records that when his lieutenant Caius Trebonius was building a movable tower at the siege of Marseilles, the only method of protecting the workmen from the darts of engines[35] was by hanging curtains woven from cable-ropes on the three sides of the tower exposed to the besiegers.[36] [35] Balistas. [36] ‘For this was the only sort of defence which they had learned, by experience in other places, could not be pierced by darts or engines.’ Cæsar’s _Commentaries on the Civil War_, Book II., Chapter IX. Procopius relates that during the siege of Rome in 537 by Vitiges King of Italy, he saw a Gothic chieftain in armour suspended to a tree which he had climbed, and to which he had been nailed by a balista bolt which had passed through his body and then penetrated into the tree behind him. Again, at the siege of Paris by the Northmen in 885–886, Abbo writes that Ebolus[37] discharged from a balista a bolt which transfixed several of the enemy. [37] Abbot of Saint-Germain des Prés and one of the chief defenders of the town. With grim humour Ebolus bade their comrades carry the slain to the kitchen, his suggestion being that the men impaled on the shaft of the balista resembled fowls run through with a spit previous to being roasted. Not only were ponderous balls of stone and heavy bolts projected into a town and against its walls and their defenders, but, with a view to causing a pestilence, it was also the custom to throw in dead horses, and even the bodies of soldiers who had been killed in sorties or assaults.