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…Flasco, where Water breaking forth from the bottom of the Lake, dos mightly tumultuate; And, which is wonderful to relate, here are beheld two Fountains together, distant scarce one pace, whereof one dances and leaps with most hot and boyling, the other with most cold and freezing water. Hence a burrow of subterraneous fire through whole Tuscany,…
https://www.wichita.edu/academics/fairmount_las/geology/wparcell/Kircher/volcanoes/chapter3.php