In taking a general survey of the volcanic phenomena of the globe, no fact comes out more strikingly than that of the very unequal distribution, in different districts, both of the great habitual volcanic vents, and of the minor exhibitions of subterranean energy. [Sidenote: VOLCANOES OF THE CONTINENTS.] Thus, on the whole of the continent of Europe, there is but one habitual volcanic vent--that of Vesuvius--and this is situated upon the shores of the Mediterranean. In the islands of the Mediterranean, however, there are no less than six volcanoes; namely, Stromboli and Vulcano, in the Lipari Islands; Etna, in Sicily; Graham's Isle, a submarine volcano, off the Sicilian coast; and Santorin and Nisyros, in the Ægean Sea. The African continent is at present known to contain about ten active volcanoes--four on the west coast, and six on the east coast; about ten other active volcanoes occur on islands close to the African coasts. In Asia, twenty-four active volcanoes are known, but no less than twelve of these are situated in the peninsula of Kamtschatka. No volcanoes are known to exist in the Australian continent. The American continent contains a greater number of volcanoes than the divisions of the Old World. There are twenty in North America, twenty-five in Central America, and thirty-seven in South America. Thus, taken altogether, there are about one hundred and seventeen volcanoes situated on the great continental lands of the globe, while nearly twice as many occur upon the islands scattered over the various oceans. Upon examining further into the distribution of the continental volcanoes, another very interesting fact presents itself. The volcanoes are in almost every case situated either close to the coasts of the continent, or at no great distance from them. There are, indeed, only two exceptions to this rule. In the great and almost wholly unexplored table-land lying between Siberia and Tibet four volcanoes are said to exist, and in the Chinese province of Mantchouria several others. More reliable information is, however, needed concerning these volcanoes, situated, unlike all others, at a great distance from the sea. It is a remarkable circumstance that all the oceanic islands which are not coral-reefs are composed of volcanic rocks; and many of these oceanic islands, as well as others lying near the shores of the continents, contain active volcanoes.