GAS SPRINGS AND MUD VOLCANOES.
Carbonic-acid Springs—Grotto del Cane—The Valley of Death in Java—Exaggerated Descriptions—Carburetted Hydrogen Springs—The Holy Fires of Baku—Description of the Temple—Mud Volcanoes—The Macaluba in Sicily—Crimean Mud Volcanoes—Volcanic Origin of Mud Volcanoes 88
The Subterranean World · The Wunder Library — complete classics, free to read, with narration.