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fields were covered with a dust much resembling ashes; and in some spots this dust had been carried by the winds to the distance of five leagues. All said that they had seen, at intervals, a smoke which was red during the day, and accompanied with flames at night. These observations led people to believe that it was a volcano. But I examined the pretended ashes, and only found a dust composed of brayed marble: I attentively observed the smoke, and neither perceived flames, nor any smell of sulphur; nor did the rivulets, nor fountains, which I examined with care, present the least appearance of sulphuric matter. Thus persuaded, I entered into the smoke, and, though quite alone, went to the brink of the abyss, where I saw a large rock dart into that abyss, and observed that the smoke was only dust, raised by the fall of the rocks; the cause of which I soon after sought for and discovered. I saw that a great part of the mountain, situated above that which had fallen, was composed of earth and stones, not disposed in beds, but confusedly heaped together. I thus perceived that the mountain had been subject to similar falls; at the end of which the large rock, which fell this year, had remained without a support, and with a considerable projection. This rock was composed of hori

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zontal beds, of which the two lower were of slate, or rather of fragile schistose stone, and of little consistency; while the two beds beneath these were of a marble, like that of Porto Venere, but full of rifts which crossed the beds. fifth bed was wholly composed of slate, in vertical leaves, entirely disunited; and this bed formed all the upper part of the fallen mountain. Upon the same level summit there were three lakes, of which the waters penetrated constantly by the fissures of the beds, separated them, and decomposed their supports. The snow, which this year had fallen in Savoy in so great abundance as had never been seen in the memory of man, having increased the effort, all these waters reunited produced the fall of three millions of cubic fathoms of rock; a mass sufficient to form a large mountain. In the narrative which I have written of the fall of this mountain, and which I sent to his majesty, with a view of the mountain, I have given a more detailed account of the cause and effect of this ruin; and I foretold that it would cease in a short time, as has actually happened; so that thus I have extinguished a volcano."

Saussure proceeds to inform us, that the ruins of this mountain are situated to the north-east of the village of Servoz. Besides the sandstone

already described*, Saussure observed rocks of grey marble, and fragments of slate.

1906.

Such are some of the most remarkable exam- Rosenberg, ples of this phenomenon. In 1806, the mountain of Rosberg, or Rosenberg, near the town of Arth, fell down, and buried a considerable tract of country, with some inhabitants. A detailed account of this event was published at Paris, with three plates, representing, 1. the town of Arth, the neighbouring country, and the profile of the ruin; 2. the same scene in front, with the extent of the fall; 3. the lake and tower of Lawerts, with Roggiberg and Rosenbergt.

Dom. II. Mode xiv.

+ Derniere relation du triste désastre, causé par l'eboulement d'une partie du Roggiberg, et du Rosberg; de trente pages d'etendue, accompagnée de trois gravurès, proprement terminées en noir, de 10 pouces de haut, sur 15 de large. Chez Villequin, march. d'estampes, grande cour du Tribunat, No. 20. 9 fr.

La premiere represente le beau bourg d'Arth, les campagnes qui l'avoisinent, et le profil du l'eboulement: La seconde, l'immense catafalque, et triste tombeau, d'une partie des habitans, de la vallée d'Arth, et l'eboulement ou de face. La troisieme, le lac et la tour de Lawerts, le Roggiberg, et le Rosberg.

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numerous.

Volcanoes THE volcanic rocks may be said, with the German mineralogists, to be of the most modern formation, as every new eruption of about one hundred and fifty volcanoes scattered over the face of the globe, must produce new rocks of this description. That there are also volcanoes at the bottom

of the sea, we know, from the ejection of new islands in the seas of Greece; and in the Atlantic near Iceland, and the Azores. It may therefore be considered as a most rational conclusion, that, as the ocean occupies two-thirds of this globe, numerous volcanoes may exist at such depths, that their effects are wholly unperceivable. Dolomieu seems to have demonstrated that Depth of fuel. the matter, which supplies the prodigious eruptions of volcanoes, must lie at an immense depth beneath the crust of the earth. This position may be argued, 1. from the surprising extent of earthquakes, felt from Lisbon to Scotland, a space of 15 degrees, or about 1000 British miles. 2. From the prodigious quantity of matter ejected in the course of ages; from the comparatively small craters of Etna, for example, whole mountains, nay territories have issued; which, if drawn from a space near the surface, the mountain must long since have sunk into its own abysses. 3. From the nature of the lava, which, in some instances, has burst through the superincum

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