Note 13 — SCENE IN SCHOOL · AN EXERCISE IN COMPOSITION
Reading edition
The agger, or mound, was of chief importance in a siege. It was begun just out of reach of the missiles of the enemy, and then gradually extended towards the point to be attacked. At the same time its height gradually increased until on a level with the top of the wall, or even higher. It was made of earth and timber, and had covered galleries running through it for the use of the besiegers. Over or beside the agger a tower was moved up to the wall, often with a battering-ram (aries) in the lowest story. (See picture, p. 221.)