"There are volcanoes that have their craters under water--or rather there are submarine eruptions that would be in the form of volcanoes if they were on land. I once saw one of these eruptions while going through the eastern part of the Mediterranean, near the Santorin Islands. There was a column of dense smoke rising from the water, and it could be seen for miles; above it, and not very far up, was a cloud formed from this smoke, and it made a very noticeable contrast to the clouds on the horizon, which were tinged by the light of the setting sun. The air was filled with a smell of sulphur, and all around there were bubbles rising from the water as though the entire sea was impregnated with gas. We sailed quite near the place where the smoke was rising, and had an excellent view of it. When the eruption began there were thousands on thousands of fish killed by the sulphur, and for some days the people from the islands used to go out and get them by the boat-load. "An effect of an earthquake occurring near the sea," Doctor Bronson continued, "is the tidal wave that causes a great part of the destruction." Fred asked what was the difference between a tidal wave and an ordinary one. "The tide, as you know," the Doctor replied, "is the rising and falling of the waters of the ocean, and the seas and bays that extend from it. The ordinary wave is caused by the action of the wind blowing upon the flat surface of the water, while the tidal wave is not. In most instances where an earthquake occurs near the sea, there is a rush of water in a wave more or less great--first upon the land, and then away from it. "In 1868 there was an earthquake on the west coast of South America, which furnishes an excellent example of what I have mentioned. At first the ground shook with a frightful noise; the whole chain of the mountains in the distance trembled like reeds in the wind, and it was apparent to every one that a frightful disturbance was at hand. The United States steamer _Wateree_ was at anchor in the harbor of Arica, Peru, and one of her officers has since told me of the earthquake. He says the sea was perfectly calm at the time, and from the decks of the ship they could see the town shaking to pieces, and the hills that formed the harbor crumbling and throwing down great masses of rock.