The Archimedes' screw was one of the first methods of pumping water. It was mainly used for agriculture, as it could pump water in and out of crops. The screw was mainly powered by steam engines and wind turbines, whereas before those technologies it was human powered. If you could take apart the screw, there would be a shaft, a blade that goes around the shaft and a cylinder or a cylinder cut in half. The shaft has the blade that twirls around it and spins inside the cylinder. This effectively pumps water up the cylinder because of the slope of the blade. The slope of the blade can be looked at by unrolling the cylinder and looking at the line where the blade would be attached to the cylinder. The slope of a water pumping screw is normally around ¾. This was based off of the right angled triangle with dimensions 3,4 and 5 which gave it a perfect slope for pumping water. The number of blades on the screw can vary, it goes from one to as many as you can fit on a shaft. There is no evidence that the screw was around before 250 B.C. although there is evidence that it was used in Egypt years before.