"Near Nicolosi, not far from Monte Rosso, one of these great openings may be seen, called the _Fossa della Palomba_, 625 feet in circumference at its mouth and seventy-eight deep. After reaching the bottom of this, we enter another dark cavity, and then others in succession, sometimes descending precipices by means of ladders. At length, the vaults terminate in a great gallery ninety feet long, and from fifteen to fifty broad, beyond which there is still a passage, never yet explored, so that the extent of these caverns remains unknown. The walls and roofs of these great vaults are composed of rough bristling scoriæ of the most fantastic forms." Besides the eruptions mentioned there have been many others, such as those of 1811, 1819, and 1852. The last of these was greater than any eruption except that of 1669. It began in August, 1852, and continued until May, 1853, and was remarkable for the immense quantity of lava thrown out. [Illustration: FIG. 15. STROMBOLI, VIEWED FROM THE NORTHWEST, APRIL, 1874] We come now to the volcano of Stromboli. Stromboli, one of the Lipari islands, is situated about sixteen miles west of the Straits of Messina. Its general appearance is shown in Fig. 15. The form of the mountain is that of an irregular four-sided pyramid, which rises about 3,090 feet above the level of the Mediterranean, and stands on the bottom of the sea in water about 3,000 feet deep. If you carefully examine the appearance of Stromboli, as shown in the preceding figure, you will notice that the flat cloud which hangs over the island is made up of a number of globular masses of vapor, formed during the peculiar action of the volcano. When examined by night Stromboli presents a still more curious appearance. Since the mountain stands alone, its height permits it to be seen readily at sea for distances of at least a hundred miles. At night a curious glow of red light may be seen on the lower surfaces of the cloud. This light is not continuous, but increases in intensity from a faint glow to a fairly bright red light, then gradually decreases, and finally dies away completely. After awhile the light again appears, again gradually decreases, and disappears, and this continues until the rising sun prevents the red glow from being any longer visible. Stromboli, therefore, acts not unlike the flashing lighthouses so common on the sea coasts of all parts of the world. Indeed, it is actually used by sailors in the Mediterranean for the purpose of showing them their direction. For this reason Stromboli is commonly called "The Lighthouse of the Mediterranean."