19th Century Technology at a Grist Mill

These two massive circular stones sit in an eastern Ontario forest, the Shaw Woods. These artifacts are from a 19th century grist mill, a mill that used the energy from moving water to grind grain into flour. This early enterprise was created by the Shaw family. Arriving from Scotland in 1847, John and Barbara Shaw saw the potential in the moving water of the Snake River and used it, building a dam to harness the energy. This image shows the facility at its peak. The river powered both a sawmill and a three-story grist mill. At this time, pioneer farmers in the area were growing a variety of crops, including wheat. These heads of wheat contain seeds. The seeds are harvested and separated from the plant, as I'm demonstrating here. These are the seeds. They are ground between the stones in a grist mill to produce flour. This is flour. It is the main ingredient in bread. The Shaw mills stopped running in the early 20th century. The forest has reclaimed the landscape. But look closely and you will find evidence of this early enterprise. Evidence like this section of stone foundation wall, and the raceways, canals that moved water into and away from the mills. Today, the old mill site and adjacent old growth forest is home to the Shaw Woods Outdoor Education Center. Open to the public, the site has an extensive network of walking trails and interpretive signage. Details about the site can be found at shawwoods.ca. There are very few water-powered grist mills still operating in North America, but there are a few, and this is one of them. Named Watson's Mill, this grist mill is located in Manitick, Ontario. It was constructed in 1860. Amazingly, 155 years later, it still grinds grain into flour. The Shaw grist mill would have operated in a very similar fashion to this one. Let's take a look at its operation. Like the Shaw mill, the energy to drive the Watson mill comes from the force produced by the hydraulic head of water contained behind a dam. This water drives turbines located in the basement of the mill. The water travels from the mill pond through control gates that are connected to the turbines. We'll go down into the basement. These are the turbines. Inside each is a rotor with blades attached to it. The outer casing has been removed from this turbine, exposing the blades. This structure contains the gate that controls the water. The shaft extending from it is connected to a wheel on the first floor. This wheel is turned to open and shut the gates. Power from the turbines is transferred through the rotating shaft that extends from each one. This mill has six turbines. They all play different roles in the functioning of the mill. The larger turbines can produce 40 horsepower if the water flow is sufficient. The process works like this. Dried grain, in this case wheat, is dumped into a hopper on the first floor. The wheat flows out of the bottom of the hopper and is picked up by an elevator, a series of buckets that carry the grain to the third floor. This elevator is powered by one of the turbines in the basement. We are now inside the third floor of the mill. On the third floor, the wheat is dumped out of the elevator into a large storage bin called the garner bin. The garner bin sits on the second floor. Both the elevator and bin are sealed. We can't see this part of the process. The wheat falls from an opening in the bottom of the garner bin into the grain chute. It hangs from the ceiling of the first floor. This chute carries the wheat to the millstones. There are two large circular millstones inside this structure. They lie flat, one on top of the other. The upper stone, called the runner, rotates. These stones are just like the two millstones standing in the forest at the Shaw Woods. Wheat trapped between them is ground to flour when the upper, or runner stone, starts turning. The lower stone, the bedstone, does not rotate. The grain enters the stones through an opening in the center of the runner stone. A special pattern cut in the surface of the stones moves the ground grain to the outer edge of the bedstone where it falls inside the structure. There are two sets of control wheels mounted close to the stones. The small wheel adjusts the distance between the two stones. The miller fine-tunes this distance to create the best flour. The large wheel controls the gate that feeds flowing water to the turbine that will drive the runner stone. Before opening the gate to start the turbine, the miller primes the stones with handfuls of wheat. This is to prevent the stones from running dry, creating sparks and possibly damaging the stones. With the stones primed, the miller now turns the large wheel to open the water gate. In the basement, water starts to flow, hitting the blades of the turbine. The runner stone starts to turn. The grain is crushed between the stones, creating coarse flour. The flour at this point in the process is actually called grist. That is why this building with its machinery is called a grist mill. The grist requires some more processing before it becomes flour. Managing the stones is a critical part of this process. The rate of rotation and gap must be carefully adjusted to create the best grist. This access port allows the miller to remove small samples of grist. Based on the texture of the grist, he will adjust the gap between the stones and change the rate of rotation of the runner stone until he is satisfied with the quality of the grist. This warm, moist grist that is falling from the stones is directed towards an elevator where it is carried to the third floor. On the third floor, the grist is dumped onto one end of a rotating auger. The auger moves the grist along, cooling and drying as it travels. The grist falls from the end of the auger into a machine on the second floor. This is the bolter. This machine separates the flour from chaff, bran and other debris. The flour falls from the bolter through a chute onto the first floor where it is bagged. The bags of flour are ready for use. So that covers the basic operation of a grist mill. More information about Watson's Mill, including hours of operation, can be found at watsonsmill.com. I'll leave you with some sights and sounds from the mill. For more science and technology related videos, visit our website, hileroad.com. Follow the videos link.