The earliest instance of the use of firearms by the Greeks is found in Thucydides, ii. 75, where it is stated that at the siege of Platæa, 429 B.C., the Platæans found it necessary to protect a wooden wall by skins and hides against the fire-arrows (πυρφόροις ὀïστοῖς) of their Peloponnesian besiegers. By the time of the Roman Empire, fire-arrows were so well known as to be mentioned by the Latin poets,[46] and the historians speak of fire-lances which were discharged from machines[47] (_adactæ tormentis ardentes hastæ_). Vegetius, who lived in the fourth century A.D., gives the composition of fire-arrows;[48] and Ammianus Marcellinus, who lived about the same time, points out their defects. First, the fire-arrow had to be discharged with a low velocity—_ictu enim rapidiore extinguitur_; it was extinguished by the cooling effect of the air when discharged with the full force of the bow. Secondly, in addition to its low velocity (and consequently limited range) it was extinguished when covered with clay.[49] However, the composition was easy to light and hard to put out—even with clay or vinegar; its viscosity enabled it to stick to the body it struck; and, becoming more and more fluid from the heat of combustion, it “spread like wild-fire.” But the use of incendiaries was not confined to grenades and arrows. At the siege of Platæa, just referred to, the Spartans piled up faggots of brushwood against the walls, and, after pouring a mixture of sulphur and pitch on the heap, set fire to it in order to burn the town.[50] They would have gained their object but for a rainstorm which put out the fire. We have here perhaps the earliest historical account of the composition of an incendiary—429 B.C. At the siege of Delium, 424 B.C., a tree was cut down and hollowed out, so as to form a tube, and from one end of it, which was protected by a covering of iron, was hung a cauldron containing a burning mixture of charcoal, sulphur, and pitch. Into this cauldron was introduced an iron bellows-pipe, leading from the end of the tree from which it hung. Having transported the machine close to the wall of the town (the cauldron to the front), the besiegers inserted the snout of a large bellows into the other end of the hollowed tree, and blew them. A great flame was thus produced; the wall, in which there was much wood, was set on fire; the heat of the fire and the vapour of the incendiary drove the defenders from the walls, and the town fell.[51] Its simplicity shows that the mixture belongs to the infancy of incendiaries in Greece. We meet with fire-ships as early as 413 B.C., when the Syracusians employed one ineffectually against the Athenian fleet;[52] and a special incendiary for naval use is recommended by Æneas, the tactician, about 350 B.C. It consisted of sulphur, pitch, incense, pine-wood, and tow. The mixture was stowed in egg-shaped, wooden vessels, admirably adapted for their purpose, which were thrown lighted upon the enemy’s decks.[53]