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derable. The

a very confiderable height. The fire next opened itself a paffage, dividing into two branches, the first to the west of the Mount del Mazzo, which it enclofed, and the other along the wood and vineyards of Rugalira for about a league.

derable. The lava continues its courfe towards Palermo, from whence it is now diftant no more than eight miles; and this is thẹ richest and best cultivated country of Mount Etna.

Of the Effects of Volcanos, and of the hot Springs, in Iceland. Frem Dr. Von Troil's Letters.

At the end of five days the fire feemed to be diminished, and advanced but very flowly; but it was foon perceived again in a very fenfible degree; and on the 5th Beffefter, the dwelling

of this month [July] threw out fuch a prodigious quantity, that the arm of the lava, which was then only thirty feet broad, augmented to fifty, in about half an hour, and it ftill continues with the fame force. But as it finds the first lava cooled, it runs upon it, raifing it to the height of more than thirty feet, in throwing it up forward, and on the fides; fo that if the refiftance this new lava is obliged to combat retards its progrefs, it nevertheless extends it in breadth, and produces the fame deftructive effects.

On the furface of this lava, in almost its whole extent, we obferve evaporations, or globes of fire of different colours, according to the greater or lefs quantity of bitumen, fulphur, arfenic, and vitriol, of which the mafs is compofed, and which the chymifts, who have analyzed it, fay is very plentiful.

The damage already caufed by this eruption is eftimated at 40,00 Sicilian crowns; but many perfons apprehend it to be more confi

E caft anchor not far from

WE

place of the celebrated Sturlefon, where we found two tracts of lava called Gorde and Hualey-re-Hraun, (for what we and the Italians call lava is in Iceland called Hraun, from Hrinna, to flow) of which the last particularly was remarkable, fince we found there, befides a whole field covered with lava, which muft have been liquid in the highest degree, whole mountains of tuff. Chance had directed us exactly to a spot on which we could, better than on any other part of Iceland, confider the operations of a fire which had laid wafte a tract of ten or twelve miles*. We spent feveral days here in examining every thing with so much the more pleafure; for we found ourselves, as it were, in a new world.

We had now feen almoft all the effects of a volcano, except the crater, from which the fire had proceeded in order therefore to examine this likewife, we undertook a journey of twelve days to Mount Heckla itself; we travelled

*The miles mentioned by Dr. Troil are always Swedish, ten and a half of which are equal to a degree on one of the great circles of the globe; and therefore, one Swedish mile is nearly equal to fix English ftatute-miles. Ten or twelve miles are therefore fixty or feventy-two English miles.

*

fifty or fixty miles over an uninterrupted tract of lava, and gained the pleasure of being the firft who ever reached the fummit of this celebrated volcano. The caufe that no one had been there before is partly founded in fuperftition, and partly in the extreme difficulty of the afcent before the laft eruption of fire. There was not one of our company who did not wish to have his cloaths a little figned, only for the fake of feeing Heckla in a blaze; and we almost flattered ourselves with this hope, for the bishop of Skallholt had informed us by letter, in the night between the 5th and 6th of September, the day before our arrival, flames had proceeded from

it;

willingly omit it, as I hope to 'fatisfy your curiofity, as foon as the collection I made of them arrives in Sweden.

but now the mountain was more quiet than we wished. We however paffed our time very agreeably, from one o'clock in the night till two next day, in vifiting the mountain. We were even fo happy, that the clouds which covered the greatest part of it difperfed towards evening, and procured us the most extenfive profpect imaginable. The mountain is fomething above five thoufand feet high, and feparates at the top into three points, of which that in the middle is the higheft. The most inconfiderable part of the mountain confifts of lava, the reft is ashes, with hard, folid ftones thrown from the craters, together with fome pumice ftones, of which we found only a fmall piece, with a little native fulphur. A defcription of the various kinds of ftones to be found here would be too prolix, and partly unintelligible ; and I fo much the more

Amongst many other craters or openings, four were peculiarly remarkable; the firft, the lava of which had taken the form of stacks of chimneys, half broken down ; another, from which water had ftreamed; a third, all the ftones of which were red as brick; and laftly, one from which the lava had burst forth in a stream, and was divided at fome diftance into three arms. I have faid before, that we were not fo happy to fee Heckla vomit fire; but there were fufficient traces of its burning inwardly; for on the upper half of it, covered over with four or five inches deep of fnow, we frequently obferved fpots without any fnow; and on the highest point, where Fahrenheit's thermometer was at 24° in the air, it rose to 153° when it was fet down on the ground; and in fome little holes it was fo hot, that we could no longer obferve the heat with a fmall pocket thermometer. It is not known whether, fince the year 1693, Heckla has been burning till 1766, when it began to vomit flames on the first of April, burnt for a long while, and destroyed the country many miles around. Laft December fome flames likewife proceeded from it; and the people in the neighbourhood believe it will begin to burn again very foon, as they pretend to have obferved, that the rivers thereabouts are drying up. It is believed that this proceeds from the mountain's attracting the water, and is confi

* Three hundred or three hundred and fixty English miles.

dered

dered as a certain fign of an impending eruption. Befides this, the mountains of Myvatn and Kattlegia are known in this century, on account of the violent eruptions of the former, between the years 1730 and 1740, and of the latter in 1756.

But permit me, Sir, to omit a farther account of the volcano at this time*, in order to speak of another effect of the fire, which is more curious and as wonderful as the first, therefore must be the more remarkable, as there is not in any part of the known world any thing that refembles it; I mean the hot fprings of water which abound in Iceland +.

They have different degrees of warmth, and are on that account divided by the inhabitants themfelves into lauger, or warm baths, and buerer, or springs that throw up the water to a confiderable height; the first are found in feveral other parts of Europe, though I do not believe that they are employed to the fame purposes in any other place; that is to fay, the inhabitants do not bathe in them here merely for their health, but they are likewise the occafion for a fcene of gallantry. Poverty prevents here the lover from making prefents to his fair one, and nature prefents no flowers of which garlands elsewhere are made: it is therefore cuftomary, that inftead of all this the fwain perfectly cleanfes one of these baths, which is to be afterwards honoured with the vifits of his bride. The other kind of fprings mentioned above deferves

more attention. I have feen 2 great number of them; but will only fay fomething of three of the moft remarkable. Near Laugervatn, a small lake of about a mile in circumference, which is about two days journey diftant from Heckla, I faw the firft hot fpouting fprings; and I must confefs that it was one of the most beautiful fights I ever beheld. The morning was uncommonly clear, and the fun had already begun to gild the tops of the neighbouring mountains ; it was fo perfect a calm, that the lake on which fome fwans were fwimming was as fmooth as a looking-glafs, and round about it arofe, in eight different places, the fteam of the hot fprings, which loft itself high in the air.

Water was fpouting from all thefe fprings; but one in particular continually threw up in the air a column from 18 to 24 feet high, and from 6 to 8 feet diameter; the water was extremely hot. A piece of mutton, and fome falmon trouts, as likewife a ptarmigan, were almost boiled to pieces in fix minutes, and tafted excellently. I wish it was in my power, Sir, to give you a defcription of this place as it deferves; but I fear it would always remain inferior in point of expreffion. So much is certain at leaft, nature never drew from any one a more chearful homage to her great Creator than I here paid him.

At Reikum was another spout of the fame fort; the water of which, I was affured, rose to 60 or 70 feet perpendicular height fome years

* Dr. Troil treats more at large of the Icelandic volcanoes in his 18th and 19th letters; and in the 20th he speaks more particularly of mount Heckla. The 21st letter treats more fully of the hot fprings in Iceland.

ago;

ago; but a fall of earth having almost covered the whole opening, it now spouted only between 54 and 60 feet fideways. We found here a great many petrified leaves in this place, as, likewife fome native fulphur, of which alfo the water had a much stronger tafte than any where else.

I have reserved the most remarkable water spout for the end; the defcription of which will appear as incredible to you as it did to me, could I not affure you that it is all perfectly true, for I would not aver any thing but what I have feen myself. At Geyfer, not far from Skallholt, one of the epifcopal fees in Iceland, a most extraordinary large fpouting fountain is to be feen, with which the celebrated water-works at Marley and St. Cloud, and at Caffel, and Herrenhaufen near Hanover, can hardly be compared. One fees here, within the circumference of half a mile, 40 or 50 boiling fprings together, which, I believe, all proceed from one and the fame refervoir. In fome the water is perfectly clear, in others thick and clayey; in fome, where it paffes through a fine ochre, it is tinged red as fcarlet; and in others, where it flows over a paler clay, it is white as milk.

The water fpouts up from all, from fome continually, from others only at intervals. The largest fpring, which is in the middle, particularly engaged our attention the whole day that we fpent here, from fix in the morning till feven at night. The aperture through which the water arofe, and the depth of which I cannot deter

mine, was 19 feet in diameter; round the top of it is a bafon, which, together with the pipe, has the form of a cauldron; the margin of the bafon is upwards of nine feet one inch higher than the conduit, and its diameter is of fifty-fix feet. Here the water does not spout continually, but only by intervals feveral times a day; and, as I was informed by the people in the neighbourhood, in bad rainy weather, higher than at other times.

On the day that we were there, the water fpouted at ten different times, from fix in the morning till eleven A. M. each time, to the height of between five and ten fathoms; till then the water had not rifen above the margin of the pipe, but now it began by degrees to fill the upper bafon, and at last ran over. The people who were with us told us, that the water would foon fpout up much higher than it had done till then, and this appeared very credible to us. To determine its height therefore, with the utmost accuracy, Dr. Lind, who had accompanied us on this voyage in the capacity of an aftronomer, fet up his quadrant.

Soon after four o'clock we obferved that the earth began to tremble in three different places, as likewife the top of a mountain, which was about three hundred fathoms diftant from the mouth of the fpring. We also frequently heard a fubterraneous noife like the difcharge of a cannon; and immediately after a column of water fpouted from the opening, which at a great height divided

About three English miles.
3

itfelf

itself into feveral rays, and, according to the obfervations made with the quadrant, was ninety-two feet high. Our great furprize at this uncommon force of the air and fire was yet increased, when many ftones, which we had flung into the aperture, were thrown up again with the fpouting water. You can eafily conceive, Sir, with how much pleafure we fpent the day here; and indeed, I am not much furprized, that a people fo much inclined to fuperftition as the Icelanders are, imagine this to be the entrance of hell; for this reafon they feldom pafs one of thefe openings without fpitting into it; or, as they fay, uti fandens mun, into the devil's mouth.

Of the Bafaltic Pillars. From Profeffor Bergman's Letter to Dr. Troil.

OF

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F all the mountains hitherto known, there are without doubt not any more remarkable than thofe that are compofed of angular pillars. A few years ago only one or two of this kind were known; but new ones are daily discovered, which is a plain proof how much our attention requires being rouzed to prevent it from flumbering, on the most important occafions.

It cannot be much doubted that there has been fome connections between thefe pillars, and the effects of a fubterraneous fire, as they are found in places where the figns of fire are yet vifible; and as they are even found mixed with lava, tuff, and other fubftances produced by fire.

The cause of the regular form of

these pillars is a problem which we have hitherto been unable to folve fatisfactorily. This difficulty has appeared fo infurmountable to fome, that they have thought it impoffible to be the effects of nature, and have confidered them as works made by human hands: this idea betrays the utmost ignorance in regard to the true nature of thefe mountains of pillars, and does not even deferve a refutation.

As far as we know, nature makes use of three methods to produce regular forms in the mineral kingdom, namely, that of cryftallization or precipitation 2dly, the crufting or fettling of the external furface of a liquid mafs whilft it is cooling and, 3dly, the bursting of á moift fubftance whilft it is drying.

The first method is the most common, but to all appearance nature has not made ufe of this in the prefent cafe. Cryftals are feldom or never found in any confiderable quantity running in the fame direction, but either inclining from one another, or, what is still more common, placed towards one another in feveral floping directions. They are alfo generally separated a little from one another, when they are regular; the nature of the thing likewife requires this; becaufe the feveral particles, of which the cryftals are compofed, muft have the liberty of following that power which affects their regular difpofition.

The bafalt columns, on the contrary, whofe height are frequently from thirty to forty feet, are placed parallel to one another in confiderable numbers, and fo clofe together that the point of a knife can hardly be introduced between them. Befides, in most

places,

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