It is obvious how the legend arose of the hundred-armed giant Typhœus or Enceladus, who was fabled to lie buried beneath the region between Etna and the Phlegræan Fields. The belching of the volcano suggested to the popular imagination, which so loved to personify the powers of nature, the gasping of an imprisoned monster. The tremors so constantly affecting the islands were his quiverings as he lay on his uneasy, burning bed, and the earthquakes that from time to time shook the region marked how he tried now and again to shift his position there. As intercourse with the West made the volcanic phenomena of that region more familiar, the mythological interpretation underwent gradual modification. On the one hand, it was observed that eruptions from Etna, sometimes disastrous enough when they occurred, took place at irregular and often widely separated intervals. On the other hand, it was noticed that among the Æolian Islands, which lay to the north, within sight of the Sicilian volcano, subterranean rumblings and explosions were of daily occurrence. The Cyclops of older time, being no longer extant above ground, came to be transferred in popular fancy to the underground regions as associates of Hephaistos or Vulcan. The incessant commotion below the surface suggested the idea of a subterranean workshop, where these beings were employed in forging the thunderbolts of Jove and in making arms and implements for other gods and heroes. Accordingly the belief gradually spread over the ancient world that the god of fire had his abode under Sicily and the neighbouring islands. Further, the abundant discharges of steam and vapours, both in the quiescent and the active phases of volcanic eruptivity, suggested that somehow they were due to wind imprisoned within the earth, and led to the myth which represented the god of the winds as having his home in the same subterranean caverns. It has often occurred to me that one phenomenon, connecting the meteorological conditions of the atmosphere with the volcanic activity of the Æolian Islands, which must have early attracted attention, would not improbably react on mythological beliefs in that part of the Mediterranean basin. Though continually in a state of eruption, Stromboli is said to be more especially active when atmospheric pressure is low. Its clouds of steam and discharges of stones are most marked before or during stormy weather, and are consequently more conspicuous in winter and spring than in summer and autumn. Since the days of Polybius and Strabo, the fishermen of the region have regarded the cloud-cap of that volcanic cone as a trustworthy indication of the kind of weather to be expected.