iE T N 



to a difcharfff of cannon in llio wide abyfa, which 

 bciig reflcitcd from the various caverns products vevcr- 

 ber.itions of the moil alarming kind. By means of tiicfe, 

 foiii'di, wliich in the open air would be confidcrcd as 

 flight cxplofioni, become more tremendous than the loudell 

 thundtr. 



^Vhen Spallanzani vifitcd this mountain, he obfened, 

 when he was at the diftancc of two miles and a halt from 

 the limit of his iourney, two white columns of fmoke, whkh 

 arofe from its fummit ; one, towards the north-eail fide 

 of the mountain, and another towards the north-well ; fe- 

 veral other flrcams of fmoke, which arofe from inferior 

 parts towards the weft, purfued the diieclion of thefe two 

 larger columns. As he proceeded, he met.w!lh a torrent of 

 lava, which he was obliged to crof3 in order to anivc at the 

 fmoking fummit. This torrent was covered with fcorix, 

 ^vhich projected in fome places in a variety of prominent 

 points, and in others funk in hollows, which rendered his 

 paffage extremely difficult j and the lava itfclf, though the 

 interval from its difeharge was 1 1 months, was in many 

 parts of it red-hot. His difficulties increafed as he pniTcd 

 that tract, which may properly be called the cone of A^tna, 

 and which, in a right line, is about a mile in length. Hav- 

 ing airived, after mnch labour and fatigue, within 150 

 paces from the vertex of the cone, he found himfelf enve- 

 loped by the vapours of the feveral ilreams of fmoke that 

 idutd from the top and fides of the mountain ; and his pro- 

 grefs was rendered extremely hazardous by the effect which 

 thefe noxious vapours produced on his refpiration. He 

 foon, however, recovered his llrength and refolution, and 

 arrived at the utmoft fummit of the mountain, where he 

 began to difcover the edges of the cratei;. Here he viewed 

 with aftonilhment the configuration of the borders, the in- 

 ternal fides, the form of the immenfe cavern, its bottom, 

 and an aperture which appeared in it, the melted matter 

 which boiled within, and the fmoke which afcended from it ; 

 and he has minutely defcribed the feveral appearances from 

 his own attentive and accurate obfervation. The upper 

 edges of the crater, which are broken and indented in fe- 

 veral places, arc, as he judged by the eye, about a mile and 

 a half in circuit, and form an oval, the longell diameter of 

 .which extends from cafl to welt. Its internal fides, which are 

 inclined at different angles in its feveral parts, form a kind of 

 i'unncl of a conical figure, and abound with concretions, 

 which he found to be the muriate of ammoniac. The bottom 

 was nearly an horizontal plane, about two-thirds of a mile in 

 circumference ; in which plane was vifible a circular aperture, 

 about five poles in dia!nttcr, from which proceeded the 

 largeft of the two columns of fmoke, obferved before he 

 arrived at the fummit of jEtna. This column appeared at 

 -its o.-igin to be about 20 feet in diameter, and whilft it re- 

 mained within the crater, afcended in a perpendicular di- 

 refllon ; but when it arofe above the edges, it was made 

 to incline towards the weft by a light wind ; and afterwards 

 it dilated into an extended and rare volume. The fmoke 

 was of a white colour. Within the crater Spallanzani ob- 

 f.-rved a liquid and ignited matter, which continually undu- ■ 

 latcd and boiled, alternately rifing and falling, without 

 fprcading ovtr the bottom. This, he fays, was the melted 

 lava, which had arifen to that aperture from the bottom of 

 the ^tnean gulf. Several large ftoncs were thrown into 

 the crater, fome of which ftruck the liquid lava and pro- 

 duced a found fimilar to that which would have been oc- 

 cafioiied by their failing into a thick tenacious paflc ; but 

 the ftoncs which fell on the bottom rebounded, and their 

 found was different from that of the others. Hence our 

 author infers, that the bottom muft. be thick and folid, 



JE T N 



which, if this were not the cafe, would have been broken by 

 heavy Hones falling from fo great a height. 



The fummit of jEtna, funounded with large maffes of 

 lava, is exhibited in Plate i. Nat. Hist. fig. 2. A. A. A. 

 reprefcuts one edge of the lava of 17S7, which iffued from 

 the upper crater. B. B. is the circumference of the crater, 

 with its cleft. C. C. through which the internal part is 

 difcernible. D. is the flat bottom of the crater ; and E. 

 the aperture in the bottom, from which the larger column 

 of fmoke F. F. arofe ; which aperture, though it was at 

 one fide of the bottom, is, for the greater dillinftiiefs of 

 view, rtprefented in the middle. G. G. is thai part of the 

 edge of the crater from v/hick its internal part is bell fecn, 

 and where the defign of it might be moll conveniently 

 taken. FI. H. is tlie fmaller column of fmoke to the north- 

 eaft. 



Spallanzani informs us, that befide the eminence on which 

 he itood, there is another to the north, a qnarter of a mile 

 higher, which renders the fummit of iEtiia properly bifur- 

 cated. The crater on this fecond pre-eminence, and from 

 which the leller column of fmoke alcends, is about one 

 half finaller tU;m the other, and is feparated from it by a 

 partition of fcoria: and accumulated lava, which lies in a 

 direftion from call to well. The Abbe has compared his 

 own ol)ler\'ation3 with thofe of others who have defcribed 

 the crater of iEtna in the courfe of 20 years, or from the 

 time when it was vifited by Caron Riedefel in 1767, to 

 that of his own journey in 1788. At the time of the Ba- 

 ron's oblervaiion, the crater was enlarged towards the ead 

 with an aperture which does not now exift ; and as the 

 ftones which were then thrown in did not return the fmallell 

 found, the bottom of the crater could not be formed with 

 the hard and flat furface which the Abbe has defcribed. 

 Within the gulf itfelf was heard a noife fimilar to that of 

 the waves of the fea, when agitated by a tempefl ; and 

 this muft probably have proceeded from the lava within the 

 bounds of the mountain, m a liquified and perturbed ftate. 

 Sir \'\^illlam Haj.nilton arrived at the fummit of ilitna on the 

 26th of October, 17^9 ; but was preventtd from dillinctly 

 viewing the lower parts of the crater by the fmoke that 

 iffued from it. From what he was able to obfer\'e he con- 

 cludes, that its figure refembled that of a funnel, diminilh- 

 ing till it ended in a point, and that this funnel was crufted 

 over with fait and fulphur. The crater was then two miles 

 and a half in circumference ; and muft have undergone 

 great changes in the interval that elapfed betv.-ecn thefe ob- 

 fervations and thofe of Riedefel, in whoTe time there muft 

 have been an abyfs as well as a funnel ; nor does the point 

 in which the funnel terminated admit of the fiat bottom 

 defcribed by Spallanzani. The dimenfions of the crater, 

 ftated by Sir WiUiam Hamilton, the Abbe accounts for by 

 fuppofing, that the partition which now feparates the great 

 crater into two parts has been produced fince the time of 

 his obfervation ; for the fum of the two circumferences 

 which the Abbe has noticed would not much differ from the 

 other meafure. Mr. Brydone, who obferved tlie crater on 

 the 29th of May 1770, fays, that it was then a circle of 

 about three miles and a Half in circumference, that it (helved 

 down on each fide, and that it formed a regular hollow, hke 

 a vaft amphitheatre, and that a great mouth opened near 

 the center. Count Borch arrived at the mountain on the 

 1 6th of Oftober 177C), and merely obferves, that the crater 

 is formed like a funnel, and that the fummit is bifurcated ; 

 a circumrtance unnoticed by Sir W. Hamilton, who affirms, 

 on the contrary, that the fummit is fingle : and the Abbe 

 therefore concludes, that one of thefe fummits has been 

 produced fince the journey of Brytfcn* in 1770. M. 



D'Orvillc, 



