The Process

• The grain ran down a chute with screens to remove sticks and rocks then to a silo to wait until the millstones were available. When the millstones were free, the grain was moved to a hopper directly over the center of the millstones. The waterwheel turned the top millstone twice a second. The bottom millstone was fixed in place. Each millstone had grooves cut into the face of the stone and the millstones cracked and smashed each kernel of grain against the sides of the cuts. The grain worked its way to the outer edge of the stone and fell off into a chute.
  
  

Power and The Millstone

• Gristmills were uniformly powered by waterwheels. The average gristmill could do quite well with the power supplied by a stream 5 feet across and 2 feet deep. Water was kept behind the mill house by a dam, usually 9 to 12 feet high and fed to the waterwheel through a channel built with boards. Waterwheels could be turned by water introduced onto the top of the wheel, the middle of the wheel or underneath the wheel. These wheels were called overshot, breastshot or undershot. Overshot wheels were three times more efficient than undershot wheels but required that the mill be built next to a steep hillside. The wheel turned a main shaft inside the grist mill and power was transferred through wooden gears to the millstones.
  
  

The Gristmill Building

• Most gristmills in the United States in the 1700s were simple buildings one or two stories tall, usually with one set of millstones. President Thomas Jefferson wrote that every town and village had a mill of some sort. Shortly after the Revolutionary War, a European traveler counted 1,100 mills in New Jersey alone. The 1840 census stated that Americans owned 28,000 mills. The typical millstream ran for three miles and could power five gristmills and four sawmills.
  
  

Gristmills Decline

• The Industrial Revolution resulted in metal parts, easy shipping and increased competition. The owners of a local gristmill couldn't compete with the larger mills and gradually lost business. The bigger mills used the same design inside and out as the simple gristmill, but they had larger, metal waterwheels powered by milldams and chutes with gates and metal gears connecting the wheel with the millstones.