Few spots on the face of the globe of the extent of Iceland could be mentioned where, within the same space, an equal number of volcanos could be found. In that island, too, many volcanic eruptions have occurred, which have been, perhaps, of greater magnitude than any others recorded as having taken place anywhere else on the earth. And yet the volcanos of Iceland are but imperfectly known, and, with the exception of two or three, not one of the rest has ever been scientifically examined. Hence the fact, that geological manuals so frequently contain most erroneous statements concerning this subject. A general uncertainty prevails as to how many volcanos have actually been in a state of eruption within historical times; dates are dealt with in a confused manner; and frequently mountains come to figure as volcanos which have never shown any signs of eruptive activity.