Georgia State Parks and Historic Sites

First the power is generated by the turbine. This turbine sits within a turbine chamber which is approximately 18 feet deep. This chamber is fed with water through a gate in the dam.

The smaller shaft you see connected to the turbine is the control rod. The angle of the vanes in the turbine is adjusted by this control rod. As these vanes open they allow water to enter the turbine, and this is what controls the power output of the turbine.

This diagram shows the lower stationary millstones and the main line shaft located directly underneath those stones.  Power is transmitted to this shaft by the belt to the pulley shown in the lower right hand corner.  As the shaft rotates power is transmitted to the stone shafts through gears.  The upper stone sits on top of the stone shaft that travels up through the bottom stone. 

The pulley shown on the left of the shaft transmits power by belt up to the top floor where it turns the bucket belts.

The lower millstone

The furrows

This picture shows the three millstones set up and ready for grinding.



So how do the millstones actually make cornmeal?
First the surface of the millstones have a rough texture, but the texture plays only one small part of how they make cornmeal.

The upper millstone has the same pattern of "grooves" or furrows as the lower stone (or bedstone) shown in the picture to the left. However, the upper millstone pattern is the reverse of the lower millstone.  

The furrows are not just grooves cut straight into the stone, they are slightly angled on one side. This angle along with the reverse pattern on the upper stone creates a scissor like cutting action as the upper stone rotates.

The furrows are cut deeper in the center of the stone and are more shallow at the outer edge. As corn enters the millstones it is caught in the deep furrows at the center. As the kernels of corn begin the grinding process they move towards the outer edge of the stone, each time encountering more and more furrows. Along the center of the stone there are only 13 furrows, compared to 42 furrows at the outer perimeter. When the corn reaches the outer perimeter of the stone it falls out and is trapped between the rotating upper stone and the inside edge of the millstone cover (also known as a vat). The meal continues to rotate until it reaches the trough and exits the vat.


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