De Westermolen, Kollumerpomp of the upright shaft. At the bottom of the upright shaft is the "crown wheel", which has 41 cogs, drives a gearwheel with 42 cogs on the axle of the Archimedes' screw. The axle of the Archimedes' screw is diameter. The screw is diameter . It is inclined at 16.7°. Each revolution of the screw lifts of water. The Archimedes' screw that pumped water into the polder has been removed. "De Westermolen" is open on Friday mornings. It is also open on Saturday mornings if there is enough wind to work the mill. De Westermolen, Kollumerpomp De Westermolen is a
Archimedes of circles. The earliest known copy of the text is in Arabic. The scholars T.L. Heath and Marshall Clagett argued that it cannot have been written by Archimedes in its current form, since it quotes Archimedes, suggesting modification by another author. The "Lemmas" may be based on an earlier work by Archimedes that is now lost. It has also been claimed that Heron's formula for calculating the area of a triangle from the length of its sides was known to Archimedes. However, the first reliable reference to the formula is given by Heron of Alexandria in the 1st century AD.