The rock that the volcano melts flows over the top like a pot boiling over and runs down the sides in streams that gradually harden into rock as they cool off. This rock is called lava, and as there is plenty of lava around Naples the people there use blocks of lava to pave their streets.

Some years ago I was in Naples after Vesuvius had been firing up. The streets of Naples were filled with what looked like gray snow. The gray snow was dust that had fallen from the volcano, but it would not melt like snow and had to be carted away and dumped into the Bay of Naples. I wanted to see what the inside of a volcano looked like. There had been a railway almost to the top, but it had been wrecked. So I climbed from the bottom to the top, though it took half a day to do so, for at each step my feet sank deep into the ashes. I looked over the edge, down into the fiery mouth of the volcano. Every now and then pieces of rock would shoot high into the air and, looking up, I would dodge those that fell near-by. Entirely, too many were falling around me, so I started back down the side of the volcano. I didn’t walk down, I jumped, for each step I took was like jumping off a house, and at each step I fell, only I didn’t hurt myself when I fell, for I sank into the ashes up to my knees, up to my waist, up to my neck. It was great fun, like jumping into a pile of hay, only it was oh, so dirty! It took me half a day to go up—it took me about ten minutes to come down—but hours to wash off the ashes when I was down, and my clothes were utterly ruined.

Some birds build their nests on the tops of chimneys, but it seems strange that people should build their homes at the foot of a volcano that may blow up and destroy them at any time. Yet long, long ago people built a city at the foot of Vesuvius, nearer even than Naples. It was called Pompeii. All of a sudden one day Vesuvius began to burn and boil and then blew up. Before any one in Pompeii knew what was going to happen, before any one had time to move from the spot where he was working or playing, Vesuvius had poured down on this little city its deadly fire and smoke and gas, and every one was killed where he stood and buried deep in dust and ashes. There the city and its people lay buried for almost two thousand years. Not so very long ago the city was dug out, its houses and temples and theaters were uncovered, and travelers can now visit the ruins, walk through the streets, and go into the houses and shops where once upon a time people went about their daily tasks and pleasures without a thought that the end of the World was coming to them in the twinkling of an eye.