THE ARCHIMEDEAN SCREW

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The Archimedean Screw (also known as a water screw), is a mechanism with a long history. The earliest water screw was first used by ancient Egyptians, to lift water from the River Nile up to the fields, for the purpose of irrigation (see below). This early type of water pump, was composed of a clay / reed tube, wound round an inner ‘rod’.

HOW IT WORKS: The water pump is anchored securely to the river bed, in a stone block. Water enters the immersed tube, as the helicoid (a type of spiral form) is rotated by a person on the river bank. The force of the water, ensures that it makes it way up the ‘pipe’ and out at the top. This takes less effort, than ‘manhandling’ heavy water filled buckets / containers, on a slippery river side / bank. Given that the Nile had a population of crocodiles, the water pump was a safer choice, than entering the river to extract water in containers.

The efficiency of the water pump design, was improved by replacing helical pipe, with an Archimedean Spiral. This is attributed to the Greek Mathematician Archimedes. It requires less effort to lift a greater volume of water.

The Archimedean Screw seen below, is enclosed within a cylinder. As the screw is turned by hand or by a motor (in modern times), the water moves upwards, until it spills from the top. This supplies water efficiently.

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