Page 63 - Demo

61Bonneyville Grist Mill, Bristol, Elkhart Co. (654.08)Historically, most early mills were run by water wheels%u2014as long as there was a suitable, stream, spring, or canal nearby. Back then, water was the most efficient power source available, but some mills used animal or human power. Over the years, most of these mills converted to more reliable steam engines, then electric motors.When vertical, upright waterwheels predominated, there were three types in use. The overshot wheel rotated as water splashed over the top; the undershot wheel had the water pushing at the bottom; and the breast wheelhad water hitting midway between top and bottom. As an alternative, some mills had a horizontal wheel, called a turbine, which was completely submerged under water. These turbines had a vertical shaft rising upward into the mill. Because the public expects to see a vertical waterwheel, the state-run Mansfield Mill in Parke County has added one%u2014even though the mill has always operated with an underwater, horizontal turbine. This vertical wheel has no function other than to look good for souvenir photos.No matter how they were powered, true grist mills used a pair of flat, circular stones, placed one atop the other, as grinders. These stones could be up to three-feet in diameter, and several inches thick. The lower stone (the bedder) remained stationary while the top stone rotated over it. The upper stone had a cone-shaped opening, wider at the top than at the bottom, bored through its center. Grist was fed into this hole and crushed as it worked its way between the two stones. Lines and patterns chiseled into the surfaces of the stones would determine the grade of flour or meal produced%u2014the closer the lines, the finer the finished product.The wood or metal axle of the waterwheel, which extended into the interior of the mill, was connected to the millstone by a series of cogged gears (often made of wood) and/or belts and pulleys. This mechanical system could be adjusted by the miller to supply just the right amount of force to turn the stone safely and efficiently. Most mills also had other equipment, such as grain elevators and conveyors%u2014all powered by the same waterwheel. Sometimes the ground grain was sifted, or screened, through a silk cloth (bolting), to yield a fine-graded flour. Grain that was too large to pass through the bolting was of lesser quality, and was know as middling(wheat) or grits (corn)%u2014and it was sold at a cheaper price. As bagged flour from large commercial operations became readily available at a reasonable price, local grist mills and roller mills began closing and disappearing. This was greatly accelerated as customers began preferring bleached and processed white flour instead of the whole-wheat variety.