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millworks


A gristmill functions like a large machine operating under a system of gears and levers. Like most colonial mills, Washington’s mill was water powered. The millpond, which provided the water source, was located on a higher elevation approximately two miles from the mill. Water traveled through a man-made millrace, which connected the mill and the millpond. At the mill, water flowed from the millrace into the flume, a wooden trough that carried water to the interior waterwheel. The flow of the water was controlled by sluice gates. The gates, made of wood, could be manually opened and closed, and functioned like an “on-off switch.”

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Eighteenth century gristmills generally had one of four different types of waterwheel: overshot wheel, pitch-back wheel, breast wheel, or undershot wheel. Washington’s gristmill had a pitch-back wheel, which turned counter-clockwise. At any one time, approximately 1/3 of the 40 buckets on the wheel were full at once. The wheel was 16 feet in diameter and was four feet wide. Each bucket held 30 gallons of water, or approximately 250 pounds. The weight of the water caused the wheel to turn and powered the mill machinery.

The main face gear was connected directly to the waterwheel by a large shaft. The main gear powered smaller gears that operated the millstones located on the second floor. Each set of stones consisted of a bedstone and a runner stone. The bedstone, which remained stationary, was recessed into the stone floor. The runner stone, connected by a shaft to the gears below, moved and cut, or sheared, the grain into flour or meal. The miller used the lighter staff to set the machine into motion and also to set the distance between the runner stone and bedstone, thus determining the consistency of the product. When the stones were set close together, the flour or meal was finely ground; setting them farther apart created a coarser ground product.

Washington’s merchant mill had two sets of stones. He ordered French buhr stones in 1772. These fine quartz stones produced superfine flour, which could be sold for a greater profit. His second set of stones, made of granite, were referred to as the country stones and were used largely to grind corn, barley, and rye. After being ground, the flour or meal was packed in wooden barrels and stored on the mill’s third floor. The barrels were raised to the upper floor by a gear and pulley system.