Gristmill

The Greek geographer Strabo reported in his Geography that a water-powered grain-mill existed near the palace of king Mithradates VI Eupator at Cabira, Asia Minor, before 71 BC.

[2] This simple arrangement required no gears, but had the disadvantage that the speed of rotation of the stone was dependent on the volume and flow of water available and was, therefore, only suitable for use in mountainous regions with fast-flowing streams.

[9] Geared gristmills were built in the medieval Near East and North Africa, which were used for grinding grain and other seeds to produce meals.

[11] The Egyptian town of Bilbays had a grain-processing factory that produced an estimated 300 tons of flour and grain per day.

[14] Early mills in England were almost always built by the local lord of the manor and had the exclusive right (the right of mulcture) to a proportion on all grain processed in the community.

Later designs incorporated horizontal steel or cast iron turbines, which were sometimes refitted into the old wheel mills.

This system of gearing ensures that the main shaft turns faster than the water wheel, which typically rotates at around 10 rpm.

This might include driving a mechanical sieve to refine the flour, or turning a wooden drum to wind up a chain used to hoist sacks of grain to the top of the mill house.

The flow of grain is regulated by shaking it in a gently sloping trough (the "slipper") from which it falls into a hole in the center of the runner stone.

In order to prevent vibrations from the millstones shaking the building apart, the stones were usually placed on a separate timber foundation, known as a husk, which was not attached to the mill walls.

That isolated the building from vibrations coming from the stones and the main gearing, and also allowed for easy re-leveling of the foundation to keep the millstones perfectly horizontal.

His inventions included the Elevator, wood or tin buckets on a vertical endless leather belt, used to move grain and flour vertically upward; the Conveyor, a wooden auger to move material horizontally; the Hopper Boy, a device for stirring and cooling the newly ground flour; the Drill, a horizontal elevator with flaps instead of buckets (similar to the use of a conveyor but easier to build); and the Descender, an endless strap (leather or flannel) in a trough that is angled downward, the strap helps to move the ground flour in the trough.

Modern mills typically use electricity or fossil fuels to spin heavy steel, or cast iron, serrated and flat rollers to separate the bran and germ from the endosperm.

Moth larvae produce a web-like material that clogs machinery, sometimes causing grain mills to shut down.