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In page Mammoth Cave National Park:

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In 1908, Max Kämper, a young German mining engineer, arrived at the cave by way of New York. Kämper had just graduated from technical college and his family had sent him on a trip abroad as a graduation present. Originally intending to spend two weeks at Mammoth Cave, Kämper spent several months. With the assistance of Ed Bishop, a Mammoth Cave Guide, Kämper produced a remarkably accurate instrumental survey of many kilometers of Mammoth Cave, including many new discoveries. Reportedly, Kämper also produced a corresponding survey of the land surface overlying the cave: this information was to be useful in the opening of other entrances to the cave, as soon happened with the Violet City entrance.[citation needed]