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Affiliated with the Local History Network of the State Historical Society of Iowa, and the Iowa Museum Association.
CRYSTAL LAKE CAVE
Ownership of the cave passed to Charles Linden who named it Linden's Cave. In the 1930s, the site was developed as Crystal Lake Cave by Bernard Markus, a son-in-law of Linden. (2) Markus operated the mine as a tourist attraction from 1932 until his death in 1944. The ownership then passed to Herbert Knockel and his wife Evelyn, a granddaughter of Markus. In 1978 the ownership of the land passed to James and Doris Rubel.
It was Rubel who hired Dennis Flint of Dubuque to replace the high voltage lines first installed in the cave in 1940. The new lights were virtually the same as used in automobiles and are operated by a series of substations that transform the voltage from 110 to 12. The less heat generated helps prevent the growth of algae. Flint's background as a theater lighting designer also came in handy when deciding where to place lights which were operated by motion detectors. (3)
See also: CAVES
1. Oldt, Franklin T. The History of Dubuque County, Iowa. Chicago: Western Historical Company, 1880, Online: http://books.google.com/books?id=u9xDAAAAYAAJ&pg=PA464&lpg=PA464&dq=Burton%27s+Furnace+%28dubuque+history%29&source=bl&ots=0CkCGLFR0v&sig=a0Ou1vN3ew6nQUYoq2aOJsXF9Mg&hl=en&sa=X&ei=j3HVT5XALaP42QXVp9iFDw&ved=0CGgQ6AEwBQ#v=onepage&q=Burton%27s%20Furnace%20%28dubuque%20history%29&f=false
2. "History," Crystal Lake Cave. Online: http://www.crystallakecave.com/history.html
3. Dickel, Dean. "Cave Lighting Illuminated," Telegraph Herald, September 13, 1993, p. 3A
Pratt, LeRoy G. Discovering Historic Iowa, Iowa Department of Public Instruction, 1975