Moat

The ditch round the ramparts of a fortre may be either wet— i.e. , full of water—or dry. In the latter, which is the commoner case, the depth should not be le than 12 feet, nor the width under 24. The more perpendicular the walls, so much the greater will be the obstruction to the enemy. In regular works the walls are usually reveted with masonry, that at the foot of the rampart being the scarp or escarp, and that below the covered way the counterscarp. See Ditch .