a small fraction of the length. Hewitt quotes from a work written by Gilles Colonne (_d._ 1316) for his pupil, Philip the Fair of France, in which he says, “Of perriers (a general name for stone-projecting machines) there are four kinds, and in all these machines there is a beam which is raised and lowered by means of a counterpoise, a sling being attached to the end of the beam to discharge the stone. Sometimes the counterpoise is not sufficient, and then they attach ropes to it in order to move the beam. The counterpoise may either be fixed or movable, or both at once. In the fixed counterpoise a box is fastened to the end of the beam, and filled with stones or sand or any heavy body. These machines cast their missiles with most exactness, because the weight acts in a uniform manner. Their aim is so sure that one may, so to say, hit a needle. If the gyn carries too far it may be drawn back or loaded with a heavier stone; if the contrary, then it must be advanced or a smaller stone supplied. Others of these machines have a movable counterpoise attached to the beam, turning upon an axis. The third kind has two weights, one fixed to the beam and the other movable round it; by this means it throws with more exactness. The fourth sort, in lieu of weights attached to the beam, has a number of ropes, and is discharged by a number of men pulling simultaneously at the cords. This last kind does not cast such large stones as the others, but it has the advantage that it may be more rapidly loaded and discharged than they. In using the perriers by night it is necessary to attach a lighted body to the projectile; by this means one may discover the force of the machine and regulate the weights of the stone accordingly.” This very valuable description of four varieties of the trebuchet at such an early date gives us an idea of the state of perfection to which they had then arrived, and from other sources may be obtained particulars relating to the size and weight of the missiles employed. They were not always of stone, but barrels of Greek fire, pitch, naphtha, and other inflammable substance were used; also occasionally the bodies of dead horses and other animals, often in a state of decomposition, barrels of offensive or putrid matter, and other missiles of a similar nature designed to cause pestilence, were thrown into towns or fortresses when the defence was obstinately prolonged. In the account left to us by Guillaume des Ormes of Carcassone in 1240, we read: “Afterwards they set up a mangonel before our barbican, when we lost no time in opposing to it from within an excellent Turkish petrary, which played upon the mangonel and those about it; so that, when they essayed to cast upon us, and saw the beam of our petrary in motion, they fled, utterly abandoning their mangonel. And in that place they made ditches and palisades, yet as often as we discharged our petrary we drove them from it.” At the siege of Bedford Castle in 1224,