The lava, during this eruption, having overwhelmed and destroyed fourteen towns, some of them containing three or four thousand inhabitants, at length arrived at the walls of Catania, a populous city, situated ten miles from the volcano. These walls had been raised sixty feet high, towards the mountain, in order to protect the city, in case of an eruption. But the burning flood accumulated against the wall, so as to fill all the space around and below that part, and finally poured over it in a fiery cataract, destroying every thing in that vicinity. From Catania the lava continued its course until it reached the sea, a distance of fifteen miles from its source, in a current about eighteen hundred feet broad, and forty feet deep. While moving on, its surface was, in general, a mass of solid rock, or cooled lava, and it advanced by the protrusion of the melted matter, through this hardened crust. As an illustration of the intense heat of volcanic matter, the Canon Recupero relates that in 1766 he ascended a small hill composed of ancient volcanic matter, in order to observe the slow and gradual manner in which a current of liquid fire advanced from Ætna. This current was two and a half miles broad; and, while he stood observing it, two small threads of lava, issuing from a crevice, detached themselves from the main stream, and approached rapidly towards the eminence where he and his guide were standing. They had only just time to escape, when they saw the hill on which they stood a few minutes before, and which was fifty feet high, entirely surrounded, and, in about fifteen minutes, entirely melted down into the burning mass, so as to be incorporated with, and move on along with it. According to Hitchcock, 77,000 persons perished during the eruption of 1769, and eighty-four square miles were covered with lava. The slowness with which lava cools may be inferred that ten years later, workmen endeavoring to sink a shaft through the bed were forced to abandon the work when near the bottom, by reason of the heat. While this was Ætna’s greatest outbreak, several of terrible destructiveness have occurred since. In 1693 an eruption was accompanied by earthquake shocks, which in three days did more damage than the lava. Catania was almost destroyed; great sea-waves rolled in upon the [Illustration: DESTRUCTION OF CATANIA.] wreck; the vessels in the harbor were dashed against each other or upon the beach: the ringing of the bells and the roar of the mountain and sea was mingled with the cries of thousands of unfortunates struggling in the ruins. Not less than 16,000 people perished in Catania alone.