FIRE-BALLS, in artillery, a composition of meal powder, sulphur, saltpetre, pitch, &c. about the bigness of a hand grenade, coated over with flax, and primed with the slow composition of a foze. This is to be thrown into the enemy's works in the night time, to discover where they are, or to fire houses, galleries, or blinds of the besiegers; but they are then armed with spikes, or hooks of iron, that they may not roll off, but stick or hang where they are desired to have any effect. See FIRE-BALLS, and LIGHT-BALLS.