The summit of the mountain is composed of scoria, and crystallizations of sulphur, with here and there heaps of lava; wherever a stick is thrust in, the opening immediately emits a volume of white smoke, and if the hand be applied to the aperture, it is soon withdrawn on account of the great heat.  The mean temperature of the summit, during the months of July and August, is 37 deg.  Fahr.  After having remained about an hour, descended to the Casa Inglese.  After an hour’s repose, proceeded downwards, visited the Philosopher’s Tower, as it is called, which tradition says was constructed by Empedocles while he was studying the various phenomena of Etna.

About a mile or two from this spot, there is a grand view of the Val di Bove.  The foreground consists of lava, forming the face of an enormous precipice, at the bottom of which is seen a lovely valley, gradually sloping down towards the coast, embracing the three several regions of the mountain, to which the purple wave of the Mediterranean forms a noble boundary:  nothing can be more varied, rich, and beautiful than this scene, as it comprises every object necessary to form a perfect landscape.

It was interesting to notice the gradual increase of vegetation during the descent.  The Senecio Christhenifolius grows at the elevation of 8,830 feet, the Juniperus Communis commences at 6,800.  Then follow the Pinus Sylv., Betula Alba, Quercus Robur, and the Fagus Sylvaticus.  The olive is seen at the altitude of 3,000 feet, and the vines flourish as high as 5,000 feet.—­United Service Journal.

[In a clever paper on the geographical position and history of Active Volcanoes, contributed by W.M.  Higgins, Esq.  F.G.S. and J.W.  Draper, Esq. to the Magazine of Natural History, is the following outline of Etna.]

Etna is entirely composed of volcanic rocks, and rises in imposing grandeur to the height of 10,000 ft. above the level of the sea.  It is about 180 miles in circumferences, and is surrounded on every hand by apparently small volcanic cones, though of no inconsiderable size, which tend in a great degree to increase the apparent dimensions of the central mountain.  Some of these cones are covered with vegetation, but others are arid and bare.  From this variety in the progress of vegetation, some persons have endeavoured to calculate the relative ages of the cones; but these opinions are exceedingly vague, as it requires a longer period to form a soil on some lavas than on others.  The earliest historical notice we have of this mountain is by Thucydides, who states that there were three eruptions previous to the Peloponnesian war (431 B.C.), to one of which Pindar alludes in his first Pythian Ode.  In the year 396 B.C. the volcano was again active; and according to Diodorus Siculus, the Carthaginian army was stopped in its march against Syracuse by the flowing lava.  But let it suffice to say, that ten eruptions previous to, and forty-eight subsequent to, the Christian era, have been recorded; some when the mountain was in the phase of moderate activity, and others when in the phase of prolonged intermittence.