My grandfather’s grandfather seems to be the main focus of this history, and was one of the first settlers in Rochester, MN. According to the family history, my grandfather writes*:
The Alexanders were the proprietors of two mills on Bear Creek within the city limits of Rochester. The "upper mill" situated at 624 - 626 South Beaver St., (now 9th Ave. S.E.) and the “lower mill” situated at 524 East College St. (now 4th St. S.E.). The upper mill was started as a woolen mill, a grist mill was added later to the south of the woolen mill. Originally, the woolen mill was powered by a water turbine, and was later converted to steam power. The dam for the upper mill was 2 ½ to 3 ft. high. I don’t remember splash boards, but they were probably used. These were two inch planks, set between iron pins placed in the top of the dam. The water above the dam could be raised 8, 10, or 12 inches, depending on the width of the planks used. Only a low head of water was required for turbine power, compared to a water wheel.
The iron turbine or enclosed reaction wheel was brought into common use about 1850 and became quite common because of their efficacy. They required little attention and were not affected by ice.
The turbine was made up of an outer case about 4 ft. in diameter and 11/2 f. high. Top and bottom plates were of cast iron, joined by a side band of iron. The vertical shaft of the runner ran thru a hole between two cast iron plates bolted to the top. The runner, shaped like a paddle wheel, could be taken out thru the opening at the top. The paddle wheel, including the vanes was made of inch thick cast iron.
The larger open end of the outer casing was connected to the penstock. Back of the opening was the gate, operated by a slide valve which was worked by a rack and pinion gear, for turning the water on or off. When open, water from the penstock rushed into the twist of the casing, and against the vanes of the runner. A wooden thrust pin below held the runner in position. In order for the water to escape thru a hole in the bottom plate of the casing the runner or paddle wheel would have to turn. Thrust pins wore usually made of oak and because they were under water, needed no lubrication.
* Or, "Guest blogging from beyond the grave". I'm thinking how he would have loved the internet for research and correspondence.