History of the Peloponnesian War

The timbers served to bind the building together, and to prevent its becoming weak as it advanced in height; it had also a covering of skins and hides, which protected the wood-work against the attacks of burning missiles and allowed the men to work in safety.

Thus the wall was raised to a great height, and the mound opposite made no less rapid progress. The Plataeans also thought of another expedient; they pulled out part of the wall upon which the mound abutted, and carried the earth into the city.

Discovering this the Peloponnesians twisted up clay in wattles of reed and threw it into the breach formed in the mound, in order to give it consistency and prevent its being carried away like the soil.

Stopped in this way the Plataeans changed their mode of operation, and digging a mine from the town calculated their way under the mound, and began to carry off its material as before. This went on for a long while without the enemy outside finding it out, so that for all they threw on the top their mound made no progress in proportion, being carried away from beneath and constantly settling down in the vacuum.