The Grain Auger: Archimedes' Screw Spun Fast in a Tube

Archimedes' screw lifts water slowly by trapping it between turns of a spiral. Close the spiral in a tight tube and spin it fast, and it moves dry grain instead: the flights push the grain along and the tube keeps it from turning with them. The auger fills bins, empties combine tanks and loads trucks, at any angle from flat to steep, with nothing but a shaft and a motor. It is a sibling of the bucket elevator: the elevator lifts straight up in buckets and needs a tower; the auger lifts at a slant in a single tube and goes where it is carried. This rung works out an auger's theoretical delivery and why its fill factor must be measured, and builds a clear-tube auger to measure it at three angles.