There came a day when the Tramontane ceased to blow down on us the cold air of the snowy Apennines, and the white cap of Vesuvius, which is, by the way, worn generally like the caps of the Neapolitans, drifted inland instead of toward the sea. Warmer weather had come to make the bright sunshine no longer a mockery. For some days I had been getting the gauge of the mountain. With its white plume it is a constant quantity in the landscape: one sees it from every point of view; and we had been scarcely anywhere that volcanic remains, or signs of such action,--a thin crust shaking under our feet, as at Solfatara, where blasts of sulphurous steam drove in our faces,--did not remind us that the whole ground is uncertain, and undermined by the subterranean fires that have Vesuvius for a chimney. All the coast of the bay, within recent historic periods, in different spots at different times, has risen and sunk and risen again, in simple obedience to the pulsations of the great fiery monster below. It puffs up or sinks, like the crust of a baking apple-pie. This region is evidently not done; and I think it not unlikely it may have to be turned over again before it is. We had seen where Herculaneum lies under the lava and under the town of Resina; we had walked those clean and narrow streets of Pompeii, and seen the workmen picking away at the imbedded gravel, sand, and ashes which still cover nearly two thirds of the nice little, tight little Roman city; we had looked at the black gashes on the mountain-sides, where the lava streams had gushed and rolled and twisted over vineyards and villas and villages; and we decided to take a nearer look at the immediate cause of all this abnormal state of things.