08 August 2010

Happy Birthday, Split Rock Lighthouse!

Split Rock turns 100 this year. It was completed in 1910, before a road reached the area. All of the building materials were shipped to the sight and hauled up the cliff, 130 feet above Lake Superior, by derrick. The U. S. Lighthouse Service operated it until 1939. At that point, the U.S. Coast Guard took command of the light until 1969 when modern navigational equipment made it obsolete. The State of Minnesota obtained the scenic landmark in 1971, and the Minnesota DNR operated it as part of Split Rock Lighthouse State Park for five years. At that point, the Minnesota Historical Society took over administration of the light and keepers' houses.

The light is kept in rotation by a 200 pound weight that drops to the floor and is cranked back up by hand. It even has a release mechanism that keeps the lens rotating while the keeper cranks the weight back to the top of the tower.

It has a third order Fresnel lens that was manufactured in Paris, France. (Fresnel lenses were ordered from one to six, with one being the most powerful and farthest reaching.) It was lit by an incandescent kerosene lamp from 1910 to 1939. In 1940 the kerosene light was replaced by a 1,000 watt electric bulb. The light is visible for 22 miles.

Once every 10 seconds, the light flashes as it rotates. And for 59 years, it kept its solitary vigil over the shore of Lake Superior north of Two Harbors, MN.

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