Page:Popular Science Monthly Volume 46.djvu/598

580 regions below, but, chameleonlike in their adaptation to their environment, they were dull reddish brown.

Lunching at the last house, an empty wooden structure, we soon passed beyond the groves of low, slender chestnut trees, above all vegetation, into the desert zone, and, leaving the mules, ascended the crater cone of Monte Gemellaro. The mountain or hill is an ash heap or cinder cone, the loose material likened by M. Émile Chaix to coke or black powdery scoriæ, with lava underneath, and it rises upward of four hundred and fifty feet above the sides of Mount Etna, with a diameter of about six hundred feet. The crater is estimated to be one hundred and twenty-five feet deep, with two fissures at the bottom three or four yards wide. It was named after the distinguished geologist and student of volcanism, the late Prof. Gemellaro, of Catania.

On the way up we passed small fissures, still steaming, and their edges incrusted with deposits of sulphur and arsenic. Such fissures are called solfataras. Small heated masses of rock and clay, still warm, lay scattered about. The structure of the inner walls of the crater is simple, reminding us of the upper edge of the crater of Popocatepetl. Under the bed of ashes the rim of the cone is made up of irregular layers of lava which slope away from the center down the sides. In fact, a crater of this sort is formed by the upthrust of masses of lava; and the repeated showers of stones, bombs, ashes, and lapilli, or coarse gravelly ashes, falling down vertically over the vent, give the regular conical shape to the crater, while the sloping sides of the funnel of the crater are formed by loose ashes rolling down the incline of the irregular vent or fissure at the bottom, which is kept clear by the passage of steam and showers of ashes during the progress of an eruption. The origin of the lava stream which threatened Nicolosi and the other towns below was mostly covered up by the thick layer of ashes. It should be understood that by the term "ashes" is meant the fragments of lava and clay, often with obsidian or volcanic glass, shattered during the more violent throes of the crater; the earthquakes and tremblings being due to the expansion of the steam pent up in the subterranean cavities and reservoirs of lava deep down in the bowels of the earth.

From the accounts published in the scientific journals we gather the facts for the following history of this eruption.

After a series of outbreaks, both from the crater of Etna and at other points below, on the 19th of May the lava began to stream down toward Nicolosi, accompanied by severe earthquakes. The stream divided, and the eruption assumed terrific proportions. The lava advanced over three kilometres in eight hours, steadily pushing on toward the village. On the 20th ten other craters opened. A dispatch stated: "Three of the craters are raging