over; but in the upper parts of the fame region, near the confines of the Regione Sylvofa, it will not begin yet for feveral weeks. As Recupero, who is a facetious and an agreeable companion, was kind enough to fit a good deal with me during my confinement, I have gathered many remarks from his converfation, that may perhaps be worthy of your attention. The variety of waters about Etna, he tells me, is altogether aftonishing. I have already mentioned the Fiume Freddo, or the river of Acis: Recupero confirms what I had been told of it. There is a lake on the north of the mountain, of about three miles in circumference, which receives feveral confiderable rivers; yet, although there is no apparent outlet, it never overflows its banks. I fuggefted that there might probably be a fubterraneous communication betwixt this and the Fiume Freddo. He faid there was no refemblance in the quality of their waters; however, I think it is probable, that in the course of fo many miles, through the caverns of Etna, full of falts and of minerals, it may both acquire its cold and its vitriolic qualities. There is another lake on the top of a mountain to the welt of Etna, the bottom of which could never be found. It is obferved never either to rife or fall, but always preferves the fame level. It is undoubtedly the crater of that mountain (which is all of burnt matter) converted into a lake. The river which fupplies the baths of Cattania is of a very different nature: it never continues the fame, but is perpetually changing. Its current is for the most part confined under ground by the lavas; but fometimes it burfts out with fuch violence that the city has fuffered greatly from it; and what is ftill more unfortunate, thefe eruptions are generally followed by fome epidemical distemper. It has now been conftantly diminishing for thefe two years paft, and is at prefent almoft reduced to nothing. They are in perpetual dread of its breaking out, and laying waste their fields, as it has fo often done before. What is exceedingly fingular, it generally bursts out after a long tract of the drieft and warmest weather. The Etnean academy have never been able to account for this fingular phænomenon. I think it is most probable that it arifes from the melting of the fnows on Etna, but I fhall not pretend to fay how. Thefe, perhaps, overfilling the caverns that ufually receive their water, the furplus is carried off into this river. The river of Alcantara certainly takes its rife from the melting of thefe fnows. Its waters, I obferved, are exactly of the fame whitish colour as all the rivers are, that run from the Glaciers amongst the Alps. There are feveral periodical springs on Etna, that flow only during the day, and ftop during the night. Thefe too, are naturally and easily accounted for from the melting of the fnows; for they melt only dur ing the day, being hard froze every night, even in the hotteft feafon. There are likewife a variety of poisonous fprings, fome of fo deadly a quality, that birds and beafts have often been found lying dead on their banks, from having drank of their water. But (what is perhaps ftill more fingular) Recupero told me, that about twenty years I 3 ago, ago, there opened a rent in the mountain, that for a confiderable time fent forth fo ftrong a vapour, that like the lake Avernus, birds were abfolutely fuffocated in flying over it. There are many caverns where the air is fo exceffively cold, that it is impoffible to fupport it for any time. These the peasants make use of as refervoirs for the fnow; and indeed they make the finest ice-houfes in the world, preferving it hard froze during the hotteft fummers. It would be endless to give an account of all the caverns, and other fingular phænomena about Etna. Kircher fpeaks of one which he faw, capable, he fays, of containing 30,000 men. Here, he adds, numbers of people have been loft from their temerity in going too far. One of thefe caverns ftill retains the name of Proferpine, from its being fuppofed by the ancients, that it was by this entry that Pluto conveyed her into his dominions; on which occafion Ovid defcribes Ceres, as fearching for her daughter, with two trees which he had plucked from the mountain, by way of torches. Thefe trees he calls Teda, which is fill the name of a tree, I have never seen any where but on mount Etna. It produces great quantities of a kind of rofin, and was the very propereit tree Ceres could have pitched upon for her purpose. This rofin is called Catalana, and is efteemed a cure for fores. the mountain. One of which was left with the Canonico Recupero, and the other we carried along with us. That which we left, Recupero affures us, had no fenfible variation during our abfence. We both left it and found it at 29 inches 8 lines and a half, English meafure. On our arrival at Cattania, we found the one we had carried up with us exactly at the fame point. I have likewife a very good quick-filver thermometer, which I borrowed from the Neapolitan philofopher, the Padre della Torre, who furnished us with letters for this place, and would have accompanied us, if he could have obtained leave of the king. It is made by Adams at London, and (as I myfelf proved) exactly graduated from the two points of freezing and boiling water. It is according to Farenheit's fcale. I fhall mark the heights in the different regions of Etna, with the rules for eftimating the elevation of mountains by the barometer, which, I am forry to fay, are fo very ill afcertained. Caffini, Boguer, and the others who have writ on the fubject, to the reproach of fcience, differing fo much amongst themselves, that it is with difficulty we can come near the truth. Etna has been often measured; but I believe never with any degree of accuracy; and it is really a fhame to the academy established in this place, called the Etnean academy, whofe original intention was to ftudy the nature and proPerties of this aftonishing mountain. It was my full intention to have meafured it geometrically; but I am forry to fay, although this is both the feat of an academy and univer univerfity, there was no fuch thing as a quadrant to be had. It is the mountain I have ever feen that would be the eafieft to measure, and with the greatest certainty, and perhaps the propereft place on the globe to establish an exact rule of menfuration by the barometer. There is a beach of a vaft extent, that begins exactly at the foot of the mountain, and runs for a great many miles along the coaft. The fea-mark of this beach forms the meridian to the fummit of the mountain. Here you are fure of a perfect level, and may make the base of your triangle of what length you please. But unfortunately this menfuration has never been made, at least with any tolerable degree of precision. tion, for every line of mercury, adding one foot to the first ten, two to the fecond, three to the third, and fo on but furely the weight of the air diminishes in a much greater proportion. Boguer takes the difference of the logarithms of the height of the barometer in lines (fuppofing thefe logarithms to confit only of five figures); from this difference he takes away a 30th part, and what remains he fuppofes to be the difference of elevation. I own I do not recollect his reafon for this fuppofition; but the rule feems to be ftill more erroneous than the other, and has been entirely laid afide. I am told, that accurate experiments have been made at Geneva, to establish the menfuration with the barometer; but I have not as yet been able to procure them. Mr. de la Hire allows twelve toifes, four feet for the line of mercury: and Picart, probably the moft exact of all the French academicians, fourteen toifes, or about ninety English feet. The palpable difference amongst thefe philofophers, muft ever be a reproach to fci ence. ter. Kircher pretends to have meafured it, and to have found it 4000 French toises; which is much more than any of the Andes, or indeed than any mountain upon earth. The Italian mathematicians are ftill more abfurd. Some of them make it eight miles, fome fix, and fome four. Amici, the laft, and I believe the most accurate that 'ever attempted it, brings it to three miles, 264 paces; but even this must be exceedingly erroneous; Height of Farenheit's Thermomeand probably the height of Etna does not exceed 12000 feet, or little more than two miles. I fhall mark the different methods of determining heights by the barometer; and you may chufe which you please. I believe the allowance in all of them, particularly in great elevations, where the air is exceedingly thin and light, is vaftly too fmall. Mikeli, whofe menfurations are esteemed more exact, has ever found it fo. Caffini allows, I think, ten French toifes of eleva At Cattania, May 26, at Ditto, May 27, at five in the mountain, mid-day fiderable quantity of 76 72 73 61 I found the magnetical needle greatly agitated near the fummit of the mountain; (the Padre della Torre told me, he had made the fame obfervation on Vefuvius) however, it always fixed at the point of Height of the barometer in inches north, though it took longer time and lines. in fixing than below. But what Recupero told me happened to him, 29 8 was very fingular.-Soon after the eruption 1755, he placed his compafs on the lava. The needle, he fays, to his great aftonishment, was agitated with much violence 27 1 for fome confiderable time, till at laft it entirely loft its magnetical power, ftanding indifcriminately at every point of the compafs; and this it never after recovered, till it was again touched with the loadftone. 265 24 2 20 5. 20 4 19 6/1/2 19 4 The wind at the fummit was fo violent that I could not make the obfervation with perfect exactnefs; however, I am pretty certain that it is within half a line. I own I had no conception of this immenfe height of mount Etna. I had heard it afferted that it was higher than any of the Alps, but I never gave credit to it: How great then was my aftonishment to find that the mercury fell almost Account of a furprizing Diver at WE ufed to admire the dex terity of some of the divers at Naples. when they went to the depth of forty-eight or fifty feet, and could not conceive how a man could remain three minutes below water without drawing breath; but these are nothing to the feats of one Colas, a native of this place, who is faid to have lived for feve ral days in the fea, without coming to land; and from thence got the furname of Pefce, or the fish, Some of the Sicilian authors affirm, that he caught fish merely by his agility agility in the water; and the credulous Kircher afferts, that he could walk across the Straits at the bot, tom of the fea. Be that as it will, he was fo much celebrated for fwimming and diving, that one of their kings (Frederick) came on purpose to fee him perform; which royal vifit proved fatal to poor Pefce; for the king, after admiring his wonderful force and agility, had the cruelty to propofe his diving near the gulph of Charybdis; and to tempt him the more, threw in a large golden cup, which was to be his prize fhould he bring it up, Pefce made two attempts, and aftonished the fpectators by the time he remained under water; but in the third, it is thought he was caught by the whirlpool, for he never appeared more; and his body is faid to have been found fome time afterwards near Jaurominum (about thirty miles diftant) it having ever been obferved, that what is fwallowed up by Charybdis is carried fouth by the current, and thrown out upon that coast, USEFUL |