History of the Peloponnesian War

They made ladders equal in height to the enemy's wall, getting the measure by counting the layers of bricks at a point where the enemy's wall on the side facing Plataea happened not to have been plastered over. Many counted the layers at the same time, and while some were sure to make a mistake, the majority were likely to hit the true count, especially since they counted time and again, and, besides, were at no great distance, and the part of the wall they wished to see was easily visible.

The measurement of the ladders, then, they got at in this way, reckoning the measure from the thickness of the bricks.