Water Circuit: Archimedean Screw

Principle of Science: Fluid Motion

The Archimedean Screw in the Court of Water is a large screw – a ramp wrapped around a cylinder – mounted at an angle and set into water at its lower end. Water is scooped into the spiral channel as the screw is turned. As the spiral turns, the water is raised to the next part of the channel and so it continues upwards. This method has been used to transport water for irrigation for hundreds of years.

A screw is a simple machine. Machines reduce the force required to do work. The Archimedean screw reduces the amount of force necessary to raise water to an elevated height. This is because the water actually travels a greater distance up the threads of the screw than it would if it were lifted using a bucket. In physics, work is defined as the force you apply multiplied by the distance the force is applied. By increasing the distance over which a force is applied, the force can be reduced. How much force a screw requires depends upon the properties of the screw – length, diameter, and pitch.

Not all labor saving devices are products of the 20th century. In fact, the Archimedean Screw, one of our greatest improvements in efficiency, goes back more that 2,000 years – and it’s still used today to raise liquids and to move pourable solids like gravel and coal.