Seppman Mill

About this property

The Seppman Mill (sometimes spelled Seppmann Mill) is a former windmill in South Bend Township, Minnesota, United States, now preserved in Minneopa State Park. It was built by Louis Seppmann, a German immigrant, between 1862 and 1864 and is now on the National Register of Historic Places. The sails and internal machinery have been removed. Seppmann was born in Westphalia, Germany, in 1835 and emigrated to the United States at age 17. He settled in Blue Earth County, Minnesota, five years later, in 1857. He made his living as a stonemason. In 1862 he used his earnings to begin constructing a wind-powered gristmill on his own land. Seppmann was only somewhat familiar with windmills from his homeland, but drew on his "considerable natural talent for mechanics and invention." Seppmann, with help from some fellow masons, built the first 10 feet (3.0 m) of the walls before being interrupted by financial difficulties and the outbreak of the Dakota War of 1862. He resumed work the next summer, joined now by neighbor Herman Hegley. Using a ramp and a wheelbarrow to convey material up the growing structure, they finished construction in 1864. Seppmann carved most of the wooden machinery himself with an axe, except for two metal cog wheels and the millstones, which had to be purchased from St. Louis for $600 (equivalent to $12,351 in 2025). The stone walls are 32 feet (9.8 m) high and conical. At the base the diameter is 30 feet (9.1 m) and the walls are two feet (0.61 m) thick, but taper to 20 feet (6.1 m) across and six inches (15 cm) thick at the top. The mill is capped with a wooden dome that could be pivoted on a track to catch the prevailing winds. There was a small platform on the outside of the dome where the miller liked to sit and smoke his pipe. The wooden arms, covered with sailcloth, spanned 72 feet (22 m). The mill had five floors, though some were very short and only held machinery. Seppmann was not a farmer, so to test the finished mill he had to borrow money and buy grain. As the American Civil War was still raging, grain was quite expensive and the bank charged him 25% interest in advance for his loan. Seppmann also needed to hire an expert to start up the mill and show him how to operate it. However, there was no wind for four or five weeks and the expert eventually gave up and went home. The first light wind didn't blow until a Sunday, but Seppmann was opposed to working on the Sabbath until his partner Hegley convinced him that if God had provided the first wind in over a month on a Sunday it must be okay. However without the expert's help, Seppmann and Hegley immediately clogged the millstone. Thinking more speed would help, they put on full sail. Instead the rising wind set the arms spinning so fast the operators couldn't stop it. The wooden parts grew so hot that the windmill was in danger of catching fire. Meanwhile, a crowd of onlookers had gathered outside, eager to see Seppmann's curiosity finally in operation and surprised that it seemed to be running so fast it might tear itself apart. In desperation Seppmann tossed something into the gears, but it shattered and a piece was flung away with such force that it shot a hole through the rim of Seppmann's hat. At last Seppmann and Hegley were able to unfurl some of the sails and halt the mill. Ultimately they learned that the clog was due to poor dressing of the millstones and after making improvements, including a better brake, were operational by late September.

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Property data from the National Register of Historic Places, National Park Service (public domain).

Description adapted from Wikipedia under the Creative Commons Attribution-ShareAlike 4.0 International License.

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