thefe fires are generally feated in beds of argillaceous fchiftus and horn ftone; often, in a fpecies of porphyry, the gluten of which is intermediate between horn-ftone and petrofilex, and contains a large quantity of fchorl, feldfpat, and greenish quartz, or chryfolite, in little rounded nodules. We would have found these very fubftances in mountains fimilar to thofe that we term primitive, and in ftrata which are buried under beds of calcareous ftone; we would have feen the fame texture, the fame component parts, and would have been convinced, by the comparison of volcanic products with thofe native and untouched fubftances, that the fluidity of lavas does not make them lofe the diftinctive characters of their bafis. In primitive mountains the mafs of thofe rocks, which I have affigned as the bafis of the more common lavas, is intermixed with micaceous rocks, with gneifs, granite, &c. and they generally reft on mafies of granite; confequently lavas muft confift of all thefe matters, and the fire must act upon them all whenever it meets with them. I have conftantly obferved, that volcanoes fituas ted at the greatest distance from the centre of the chain, or group of mountains on which they are established, produce lavas of a more homogeneous compofition and lefs varied, and which contain moft iron and argillaceous earth. Thofe, on the contrary, that are placed near the centre are more diverfified in their products, which contain fubftances of an infinity of different kinds; but I have obferved likewife, that the feat of the fire does not long remain among the granites; either the inflammation ceafes, or returns to the centre of the fchiftous rocks in its neighbourhood. bowels of the earth. The excavations and mines dug by men for the cxtraction of minerals, are nothing but fcratches made on the furface of the globe, when compared to the enor mous cavities formed by volcanoes, as they raife the immenfe maffes of moun tains which they have produced. All thofe accumulated maffes which compofe Mount Etna have been originally buried in the bofom of the earth, and when they are attentively examined, we may obferve in them fuch substan, ces as are moft common at great depths. Naturalifts may confider fubterranean fires as miners that tear from the bow. els of the earth the fubftances formed there, and present them to obfervation: they fhew, for instance, that fchorls and porphyries, which are but rare on the furface, are very common in the interior parts of the earth. But if we may acquire much information with regard to volcanoes by studying those mountains, the volca noes themfelves may afford great helps in investigating the matters that are found in greatest quantities in the peo I was certain that, in fome part of Sicily, there exifted granites, porphy ries, with fchiftous and argillaceous horn ftones, although I had no other evidence of thefe fubftances than the layas of Etna. I had traversed three fourths of that island before I met with them; I had, in oppofition to my opinion, the testimony of the ple of the country, who affirmed, that fuch fofils did not exift there; but I was only the more anxious to fearch for them, as I was convinced that Etna muft have been in the neighbour hood of mountains that contain them, I at last found that the mountains which form the whole point of Sicily, called Cape Pelorus, contain fuch rocks as I have mentioned; I faw that the base of these mountains was produced on one fide under Mount Etna, and under the Lipari islands on the other, Confequently, we must believe that thefe mountains have furnished the materials on which the volcanoes have for thoufands of years exerted their power; and I was enabled, by traverfing them, to difcover why the products of Lipari differ from thofe of Etna. I travelled over feveral times, and in every direction, the group which thefe mountains form; I climbed the higheft fummits, and, with infinite labour, and even danger, fucceeded in acquiring an idea of their collective and relative fituation. They have obtained the name of Montes Neptunei, or Mons Pelorus. They occupy the whole point of Sicily, which terminates at the Pharos of Meffina; they form a group with a fort of triangular bafe, the ahgles of which are Taormina, the Pharos, and Pati. One fide of the triangle faces the east, and is formed by the mountains that run along the coaft of Meffina: the fecond looks to the northweft, and follows the coast of Melaz zo; the third is on the fouth-weft oppofite to Etna, and prefents an unfurmountable barrier to the lavas of that volcano. It is marked by a line drawn across the country from the point of Pati to Taormina. The Neptunian mountains may be confidered as the extremity of the Apennines, for they are feparated only by the channel of Metlina from the mountains of Calabria, which they refemble alfo in the materials of which they are compofed. Of all the mountains in this group the largest and higheft is the Monte Scuderi, which is nearly in the centre. Except Etna, it is the highest in all Sicily, and fnow lies on its top the whole year. It forms the point of feparation between rocks of very different component parts, which here unite in forming its immenfe bulk. Towards the North, the granites a-bound on its fides, and its base is buried under the lateral mountains formed by that compound rock. On the South, it produces the horn ftone, petrofilex, and argillaceous fchiftus, which include a great variety of metallic ores. Thus it interpofes between the granites and Etna a bed of fchift, thro' which the volcano must make its way before itreaches the granitical rock; while, on the other hand, the granite extends itfelf on the furface to the mountain of Cape Melazzo, which is partly formed of it, and then enters the fea, where it can be difcovered by founding at a great diftance from the fhore in the direction of the Lipari iflands. This unequal distribution of the granite and schiftous rock in the Neptunian mountains, explains the caufe of the difference between the productions of the volcanoes in the Bolian islands, and of those on Etna. Thefe iflands reft almoft immediately on granite, or are feparated from it by a very thin ftratum of argillaceous rock which contains porphyry; but the burning volcano of Sicily is fituated on the prolongation of the fchif tous rock, which it must pierce before it reaches the granite; and accordingly very little of its lava feems to have granite for its bafis. If the feat of the fire was ftill more distant from the centre of the mountains, their lavas would be more homogeneous and lefs varied, because the fchift which fucceeds the horn-stone is not so various, and hardly includes any bodies foreign to its own substance. Thus the lavas in the extinguished volcanoes of the Val di Notto, which lie fifteen leagues fouth-eaft from Etna, contain neither granite nor porphyry, but have for their bafis fimple rocks, with particles of chryfolite and some schorls. I found in the Neptunian mountains rocks fimilar to thofe that I have obferved in the erupted matter of volcanoes. The granites which extend to Melazzo, and which are opposite to Lipari, contain, interpofed between their ftrata, an immenfe quantity of fcaly and micaceous rocks, black and white, with fofile granites or gneifs, the bafis of which is a very fufible feldtfpat: and thefe are the fubftances to which I afcribe the formation of pumice, as I have found pieces of them almost untouched in pumice ftones. There are beds of almost pure feldtfpat, the femi-vitrification of which may have produced the opake enamel LI 2 like thered in the gullies, and which had apparently been wafhed from the inte rior parts of the mountain by water. But though the porphyries I faw here bear no proportion to thofe in the products of Etna, I was fufficiently convinced of their existence, and their analogy with thofe of volcanoes, by difcovering that the centre of thefe mountains contains a great number of them. I did not find here the antique ferpentine, though I am certain from the lavas that it does exift, and in great quantity, in the interior parts of the earth. Porphyries in general are very rare on the furface: nature generally conceals them from us by burying them under calcareous strata, or by inclofing them in fchiftous rocks with which they are almost always mixed: but we are indebted to the labour of volcanoes for informing us that they are one of the moit common fubftances in the bowels of the earth; and they are never fo much difguised by the fubterranean fire as to be mistaken in the lavas of which they form the like lava I have formerly mentioned. A Authentic Anecdotes of Alexander Selkirk. S the adventure of Alexander Selkirk was very remarkable and uncommon, I have thought it worth while to extract the following fummary of it from thofe original narratives which still exift, and fome of which are only to be found in books not very commonly to be met with. I beg leave to refer fuch of your readers, as may wish to confult them, to Funnell's Voyage round the World, Woodes Roger's Voyage round the World, Edward Cooke's Journal of Roger's Voyage, and to No XXVI. of The Englishman, by Sir R. Steele. Alexander Selkirk was born at Largo, in the county of Fife, about the year 1876, and was bred a feaman. He went from England, in 1703, in the capacity of failing-master of a small veffel called the Cinque Ports Galley, Charles Pickering captain, burthen a bout 90 tons, with 16 guns and 63 men; and in September the fame year failed from Corke, in company with another fhip of 26 guns and 120 men, called St George, commanded by that famous navigator William Dampier, intending to cruize on the Spaniards in the South Sea. On the coaft of Brazil Pickering died, and was fuc ceeded in his command by his licute Dant nant Thomas Stradling. They proceeded on their voyage round Cape Horn to the island of Juan Fernandez, whence they were driven by the ap pearance of two French fhips of 36 guns each, and left five of Stradling's men there on fhore, who were taken off by the French. Hence they failed to the coast of America, where Dampier and Stradling quarrelled, and feparated by agreement, on the 19th of May 1704. In September following Stradling came again to the ifland of Juan Fernandez, where Selkirk and his captain had a difference, which, with the circumftance of the fhip's being very leaky, and in bad condition, induced him to determine on ftaying there alone; but when his companions were about to depart, his refolution was fhaken, and he defired to be taken on board again. Happily for him, the captain then refused to admit him, and he was obliged to remain, having nothing but his cloathes, bedding, a gun, and a small quantity of powder and ball; a hatchet, knife, and kettle; his books, and mathematical and nautical inftruments. He kept up his fpirits tolerably, till he faw the veffel put off, when (as he afterwards rela ted) his heart yearned within him, and melted at parting with his comrades and all human fociety at once. "Yet believe me, Arcas; Such is the rooted love we bear mankind, All ruffians as they were, I never heard, A found fo difmal as their parting oars.' Thomfon's Agamemnon. The Cinque Ports was run on fhore a few months afterwards; the captain and crew, to fave their lives, furrendered themselves prifoners to the Spaniards, who treated them fo harfhly, that they were in a much worfe fituation than Selkirk, and continued in it a longer time. Some months after Selkirk left the South Sea in the Duke privateer, Capt. Stradling was fent a prifoner to Europe on board a French ship, and by that means got to England. Thus left fole monarch of the island, with plenty of the neceffaries of life, he found himself in a fituation hardly fupportable. He had fish, goat's flesh, turnips, and other vegetables; yet he grew dejected, languid, and melancholy, to fuch a degree, as to be fcarce able to refrain from doing violence to himself. Eighteen months paffed before he could, by reafoning, reading his Bible, and study, be thoroughly reconciled to his condition. At length he grew happy, employing himself in decorating his huts, chafing the goats, whom he equalled in fpeed, and scarcely ever failed of catching. He also tamed young kids, laming them to prevent their becoming wild; and he kept a guard of tame cats about him, to defend him when afleep from the rats, who were very troublesome. When his cloathes were worn out, he made others of goats fkins, but could not fucceed in making fhoes, which, bowever, habit, in tinte, enabled him to difpenfe with the ufe of. His only. liquor was water. He computed that he had caught 1000 goats during his abode there; of whom he had let go, 500, after marking them by flitting their ears. Commodore Anfon's people, who were there about 30 years after, found the first goat, which they fhot upon landing, was thus marked, and, as it appeared to be very old,. concluded that it had been under the power of Selkirk; but it appears by Capt. Carteret's account of his voyage in the Swallow floop, that other per fons practifed this mode of marking, as he found a goat with his ears thus flit on the neighbouring island of Masa-fuera, where Selkirk never was. He made companions of his tame goats and cats, often dancing and finging with them. Tho' he constantly performed his devotions at stated hours, and read aloud, yet, when he was taken off the island, his language, from difufe of converfation, was become fcarcely intelligible. In this folitude he continued continued four years and four months, fea without fresh provifions, the goats during which time only two incidents happened which he thought worth relating, the occurrences of every day being in his circumftances neatly fimilar. The one was, that, purfuing a goat eagerly, he caught it juft on the edge of a precipice, which was covered with bushes, fo that he did not perceive it, and he fell over to the bottom, where he lay (according to Captain Rogers's account) 24 hours fenfelefs; but, as he related to Sir R. Steele, he computed, by the alteration of the moon, that he had lain three days. When he came to himfelf, he found the goat lying under him dead. It was with great difficulty that he could crawl to his habitation, whence he was unable to ftir for ten days, and did not recover of his bruifes for a long time. The other event was, the arrival of a fhip, which he at first fuppofed to be French and fuch is the natural love of fociety in the human mind, that he was eager to abandon his folitary felicity, and furrender himfelf to them, although enemies; but, upon their landing, approaching them, he found them to be Spaniards, of whom he had too great a dread to trust himself in their hands. They were by this time fo near, that it required all his agility to efcape, which he effected by climbing into a thick tree, being shot at feveral times as he ran off. Fortunately, the Spaniards did not discover him, tho' they stayed fome time under the tree where he was hid, and killed fome goats juft by. In this folitude Selkirk remained until the 2d of February 1709, when he faw two fhips come into the bay, and knew them to be English. He immediately lighted a fire as a fignal, and, on their coming on fhore, found they were the Duke, Captain Rogers, and the Dutchefs, Captain Courtney, two privateers from Bristol. He gave them the best entertainment he could afford; and, as they had been a long time at which he caught were highly acceptable. His habitation, confifting of two huts, one to fleep in, the other to drefs his food in, was fo obfcurely fituated, and fo difficult of accefs, that only one of the fhip's officers would accompany him to it. Dampier, who was pilot on board the Duke, and knew Selkirk very well, informed Capt. Rogers, that, when on board. the Cinque Ports, he was the best feaman on board that veffel; upon which Capt. Rogers appointed him mafter's mate of the Duke. After a fortnight's stay at Juan Fernandez, the fhips proceeded on their cruize against the Spaniards; plundered a town on the coaft of Peru; took a Manilla ship off Cali fornia; and returned by way of the E. Indies to England, where they arrived the 1st of Oct. 1711; Selkirk having been abfent eight years, more than half of which time he had spent alone on the island. The public curiofity being excited refpecting him, he was induced to put his papers into the hands of Defoe, to arrange, and form them into a regular narrative. Thefe papers must have been drawn up after he left Juan Fernandez, as he had no means of recording his tranfactions there. Capt. Cook remarks, as an extraordinary circumftance, that he had contrived to keep an account of the days of the week and month; but this might be done, as Defoe makes Robinfon Crufoc do, by cutting notches in a poft, or many other methods. From this account of Selkirk, Defoe took the idea of writing a more extenfive work, the romance of Robinfor Crufoe, and very dishonestly defrauded the original proprietor of his fhare of the profits. I conclude this ftory with Selkirk's observation to Sir R. Steele, only remarking, that it is a proof how apt we mortals are to ima gine, that happiness is to be found in any fituation except that in which we happen to be. To ufe his own words, |