### How the Mill Works Operation of a Historic Grist Mill ...

A vertical rod, called the "damsel," is then used to shake the kernels downward, through the "shoe" and into the millstone. The hopper releases an average of three bushels of corn an hour for grinding. About the Millstones. The two millstones at Gray's Mill are 15 inches thick, and weigh 1 1/2 tons each.