58o THE POPULAR SCIENCE MONTHLY. 



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. Emile Chaix to coke or black powdery scorise, with lava un- 

 derneath, 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 vol- 

 canism, 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 sliape 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 



