Note 80 — Chapter VII · RAILWAY BRIDGES AND VIADUCTS.

At the back of retaining walls, such as the abutments and wing walls of bridges which were subject to the pressure of earth behind them, Mr. Brunel introduced what were termed ‘sailing courses,’ projecting shelves corbelled out at the back of the wall. The weight of earth resting on these shelves virtually increased the weight of the back of the wall, and assisted it in resisting the forward pressure of the earth.