But whatever be the source or cause, the heat and the elements of heat have been in constant activity, volcanoes and earthquakes, like the hurricane and disease, subserving important necessary purposes in the economy of nature. Humboldt was the first to remark the linear distribution of volcanic domes, which he considered as vents placed along the edge of vast fissures, communicating with reservoirs of igneous matter, and extending across whole continents. Lyell, considering that the earthquake and the volcano are probably the effects of the same subterranean process, and that the subterranean movements are least violent in the immediate proximity of volcanic vents, observes, “that if the fused matter has failed several times to reach the surface, the consolidation of the lava first raised and congealed will strengthen the earth’s crust, and become an additional obstacle to the protrusion of other fused matter during subsequent convulsions.” Thus, needful in all past time, these igneous phenomena are needful still—in supplying and indurating new lands—in repairing the waste and continual encroachments of the sea—in keeping up a salutary degree of heat over the earth’s crust, and thereby perhaps essential toward maintaining the necessary volume of the earth’s bulk. Nor will the fires within have fulfilled their law and purpose of inclosure until the ordinance of Heaven in its creation be completed, when the earth and the works therein shall be burnt up. CHAPTER II. THE ALPS—MONT BLANC. The Pennine or Western Alps constitute the loftiest group of mountains in Europe. They consist of a vast chain of isolated peaks, all of which are elevated above the region of perpetual snow. Mont Blanc, Mont Cervin, and Mont Combin attain respectively to the heights of fifteen thousand seven hundred and thirty-two feet, fourteen thousand eight hundred and fifty-five feet, and fourteen thousand one hundred and twenty-five feet, above the level of the sea. This group is succeeded by that of the Bernese Alps, of which the Jungfrau is the most conspicuous, reaching the altitude of thirteen thousand seven hundred and eighteen feet. The Helvetian Alps lie to the east and south of these two ranges, rising in Mont Rosa to the height of fifteen thousand one hundred and fifty feet into the same aerial frozen regions. The rivers Rhine and Rhone spring from the glaciers which occupy the valleys intermediate betwixt the Bernese and Helvetian mountains, while the Po, rising among the Cottian Alps on the south-west, derives its principal tributaries from the same alpine sources with its larger twin-sisters.