Dion Cassius relates, that this eruption was so violent, that cinders and sulphurous smoke were driven as far as Rome, and even beyond the Mediterranean into Africa. Heraclea was one of the two towns burned by this first conflagration of Vesuvius, which, in these latter times has been discovered at more than 60 feet deep, the surface above which was become, by length of time, arable land and fit for culture. The relation of the discovery of Heraclea is in the hands of the public, and we can only wish that some person, versed in Natural History, would examine the different matters which compose this soil of 60 feet, attending to their disposition and situation, the alterations they have produced or suffered, the direction they have taken, and the hardness they have acquired.
There is an appearance that Naples is situate on a hollow ground, filled with burning materials, for Vesuvius and Solfatera seem to have interior communications. When Vesuvius casts out lava Solfatera emits flames, and when the one ceases the other is extinguished. The city of Naples is situate nearly between them.
One of the last and most violent eruptions of Mount Vesuvius was in the year 1737.[J] The mountain vomited, by several mouths, large torrents of burning metallic matters, which dispersed themselves over the country, and flowed into the sea. Mons. Montealegre, who communicated this relation to the Academy of Sciences, observed, with horror, one of these rivers of fire, whose length, from the mountain to the sea, was about seven miles, its breadth about 60 feet, its depth 25 or 30 palms, and in bottoms or vallies 120: the matter which flowed was like the scum which issues from the furnace of a forge, &c.[K]
[J] It should be remembered, as noticed by Mr. Smellie, that the original of this work was published by our author in 1749, since when Vesuvius has undergone several eruptions.
[K] See the Hist. Acad. an. 1737.
In Asia, particularly in the islands of the Indian ocean, there are many volcanos; one of the most famous is Mount Albours, near Mount Taurus, eight leagues from Herat; its summit continually smokes, and it frequently throws out flames and burning matter in such quantities that the surrounding country is covered with cinders. In the island of Ternate there is a volcano which throws out matter like pumice-stones. Some travellers assert that this volcano is most furious at the time of the equinoxes, because certain winds then reign there, which inflame the matter that feeds, and has fed this fire for a number of years.[L]
[L] See Argensola's Travels, vol. 1, page 21.
The island of Ternate is but seven leagues round, and is only the summit of a mountain; it gradually ascends from the shore to the middle of the island, where the volcano rises to a considerable height, to the top of which it is very difficult to attain. Many rills of sweet water descend along the ridge of this mountain, and when the air is calm, and the season mild, this burning gulph is in less agitation than during storms and high winds.[M] This confirms what I have said in a former article, and seems to prove that the fire of volcanos does not proceed from any considerable depth, but from the top, or at least not far distant from the summit of the mountain; for if it was not so, the high winds could not increase their combustion. There are other volcanos in the Malaccas. In one of the Mauritius islands, 70 leagues from the Malaccas, there is a volcano, whose effects are as violent as those of Mount Ternate. Sorca island, one of the Malaccas, was formerly inhabited. In the middle of this island there is a lofty mountain, with a volcano at the top. In 1693 this volcano vomited bitumen and inflamed matters in such a great quantity as to form a burning lake, and which covered the whole island.[N]