=Aiguillon.= A city in France; while in the possession of the English in 1345, it was besieged by the Duke of Normandy, son of Philip de Valois. According to some authors, cannons were used on this occasion for the first time in France. =Aile= (_Fr._). A wing or flank of an army or fortification. =Ailettes= (_Fr._). Literally “little wings,” were appendages to the armor worn behind or at the side of the shoulders by knights in the 13th century. They were made of leather covered with cloth, and fastened by silk laces. They are supposed to have been worn as a defense to the shoulders in war. =Aim.= The act of bringing a musket, piece of ordnance, or any other missive weapon, to its proper line of direction with the object intended to be struck. =Aim-frontlet.= A piece of wood hollowed out to fit the middle of a gun, to make it of an equal height with the breech; formerly made use of by the gunners, to level and direct their pieces. =Aiming Drill.= A military exercise to teach men to aim fire-arms. Great importance is justly attached to this preliminary step in target practice. =Aiming-stand.= An instrument used in teaching the theory of aiming with a musket. It usually consists of a tripod with a device mounted upon it, which holds the gun and allows it to be pointed in any direction. =Ainadin.= Name of a field near Damas in Syria, celebrated by a battle on July 25, 633, in which Khaled, chief of the Saracens, defeated Verdan, a general of the Roman army. Verdan lost 50,000 men and was decapitated. =Ain-Beda= (Africa). An engagement at this place between the French and Arabs in October, 1833. =Ain Taguin.= “Spot of the little desert,” in the province of Algiers; here the Duke d’Aumale surprised and dispersed the troops of Abd-el-Kader. =Air-cylinder.= A pneumatic buffer used in America to absorb the recoil of large guns. For 10-inch guns, one cylinder is used; for the 15-inch, two. They are placed between the chassis rails, to which they are firmly secured by diagonal braces. A piston traversing the cylinder is attached to the rear transom of the top carriage. When the gun recoils the piston-head is drawn backwards in the cylinder, and the recoil is absorbed by the compression of the air behind it. Small holes in the piston-head allow the air to slowly escape while the gun is brought to rest. The _hydraulic buffer_ largely used abroad operates in the same way, water being used in place of air. =Air, Resistance of.= The resistance which the air offers to a projectile in motion. See PROJECTILES, THEORY OF. =Aire.= A military position on the Adour, in the south of France, where the French were defeated by the English under Lord Hill, on March 2, 1814. =Air-gun.= An instrument resembling a musket, used to discharge bullets by the elastic force of compressed air.