Fast facts about Split Rock Lighthouse

Fast facts about Split Rock Lighthouse

The Split Rock Lighthouse was in operation from 1910 to 1969. Here are some facts about the site:

- Lake Superior elevation - 602 feet above sea level.

- Cliff height - 130 feet.

- Tower height - 54 feet.

- Light source - incandescent oil-vapor (kerosene) lamp, 1910-39; 1,000-watt electric bulb, 1940-1969.

- Lens - third-order bivalve Fresnel lens, manufactured by Barbier, Bernard and Turenne Company, Paris, France.

- Official range - 22 miles.

- Flashing sequence - once every 10 seconds (0.5-second flash every 9.5 seconds).

- Tone - siren blast, 1910-1935. Type F diaphone "be-you" sound, 1936-1961.

- Sounding sequence - 2-second blast, 18-second silence.

- Effective range - 5 miles.

- Powered by Franklin 30-horsepower gasoline-driven air compressors, manufactured by Chicago Pneumatic Tool Company, 1910-19031; diesel compressors, 1932-1961.