The hydraulic ram is an interesting pump that uses water power to move water to a greater height. The principle of operation is as follows: water moving down a supply pipe closes an escape valve (E) controlled by a spring. The momentum of the moving water causes a ramming action that forces water through a supply valve (S) at the base of an air chamber. The force of the water compresses the air in the chamber. Then the air pressure equals the pressure of the moving water in the supply pipe, the supply valve closes, and the trapped water is forced out of the delivery pipe at a higher elevation. Immediately after the supply valve is closed, there is a rebound or backward flow of water that causes the escape valve to open. Then the water starts to move again down the supply pipe, builds up momentum, and the cycle repeats. The efficiency of this device may be as high as 75% under ideal conditions. The hydraulic ram, with only 2 moving parts, can operate for years without attention. It is especially valuable for providing irrigation where power is unavailable, and it should have wider use in underdeveloped areas.