Photo collection by Th.Schiöler Spiral scoops, screws and the chain pump The Archimedean screw

The Archimedean screw

An Archimedean screw on a rickshaw This screw was made by a Danish aid organization, which wanted to introduce a well-known technology into Bangladesh. It failed. [148]		The Archimedean screw in action This screw is the same as we saw in: [148]. The water is lifted just half a metre, but the flow is immense. [149]		The internal screw for the Archimedean screw The screw is made like a spiral staircase. In total, it consists of 75 steps. The staircase and housing make an undivided whole, unlike the kitchen mincer. [150]
Details of the Archimedean screw in Egypt The screw as it is made in Egypt. The construction is an invention from the third century B.C.. This is correct as regards the main features but the steel crank is a modern invention. A treading man turned the ancient screw. See the next photo. [151]		Fresco in Pompeii In the relevant literature, it has long been accepted that this fresco depicts an Archimedean screw. Unfortunately, the screw is not inclined at about thirty degrees as it must be to lift any water. We know that the Archimedean screw was turned by one or two treading men; but why not by means of a crank? Because the steel crank was yet not invented. [152]		A screw near Cairo It is hard work to turn an Archimedean screw. Even more exhausting than pedaling a bicycle. On a bicycle, you are only pressing downwards, but for the screw, it must be pushed all the way round. It needs at least twice as much power as a bicycle. [153]
A European screw This screw has three threads or blades. The capacity is immense. A screw like this is constructed for draining a large area of reclamation. [154]