Supposing the latter force to be employed, the long end of the shaft was drawn down by a windlass; the sling was laid forward in a wooden trough provided for it, and charged with the shot. The counterpoise was, of course, now aloft, and was so maintained by a detent provided with a trigger. On pulling this, the counterpoise falls and the shaft flies upwards drawing the sling. When a certain point is reached the loop end of the sling releases itself from the hook, and the sling flies abroad whilst the shot is projected in its parabolic flight.[4] To secure the most favourable result the shot should have acquired its maximum velocity, and should escape at an angle of about 45°. The attainment of this required certain proportions between the different dimensions of the machine and the weight of the shot, for which, doubtless, traditional rules of thumb existed among the mediæval engineers. The ordinary shot consisted of stones carefully rounded. But for these were substituted on occasion rough stones with fuses attached,[5] pieces of red-hot iron, pots of fused metal, or casks full of Greek fire or of foul matter to corrupt the air of the besieged place. Thus carrion was shot into Negropont from such engines by Mahomed II. The Cardinal Octavian, besieging Modena in 1249, slings a dead ass into the town. Froissart several times mentions such measures, as at the siege of Thin l’Evêque on the Scheldt in 1340, when “the besiegers by their engines flung dead horses and other carrion into the castle to poison the garrison by their smell.” In at least one instance the same author tells how a living man, an unlucky messenger from the Castle of Auberoche, was caught by the besiegers, thrust into the sling with the letters that he bore hung round his neck, and shot into Auberoche, where he fell dead among his horrified comrades. And Lipsius quotes from a Spanish Chronicle the story of a virtuous youth, Pelagius, who, by order of the Tyrant Abderramin, was shot across the Guadalquivir, but lighted unharmed upon the rocks beyond. Ramon de Muntaner relates how King James of Aragon, besieging Majorca in 1228, vowed vengeance against the Saracen King because he shot Christian prisoners into the besiegers’ camp with his trebuchets (pp. 223–224). We have mentioned one kind of corruption propagated by these engines; the historian Wassáf tells of another. When the garrison of Dehli refused to open the gates to Aláuddin Khilji after the murder of his uncle, Firúz (1296), he loaded his mangonels with bags of gold and shot them into the fort, a measure which put an end to the opposition.