Our traveller, in ascending, had supposed the Mamelen central the highest peak of the volcanic -mountain ; but he new discovered, at the distance of about 200 fathoms, a still more elevated point, which, after himself, he named Bory. It is a vast elliptic basin, the largest diameter of which is 120, -and • the smallest 100 fathoms. The sides rise perpendicularly like walls, and are 200 feet high at their greatest elevation. There were some broken -parts, however, by which the travellers could de scend into the abyss. They found it tolerably level ; but the volcanic ashes with which it was bestrewed, bid the scoria and other substances which filled it. In the centre was a crevice the depth of which they could not discover. This crater was entirely silent.
The travellers spent the night on the crater Do lomieu ; but the tremendous sounds, the blaze of light, and the singularity of their situation, scarcely allowed them to close their eyes. At about 1204 feet beneath, they perceived a stream of lava issuing from the mountain, the outlet, probably, of those substances which they saw fermenting at the bottom of the crater.
The crater is said to have been formed during w violent eruption of the volcano in 1791. In the beginning of June, a burning vapour appeared ris ing from the summit ; then the side of the mountain opened, and a vast torrent of lava rushed into the sea. On the 17th of July, a subterranean noise, like the discharge of cannon, was heard throughout le Island; aftdr which, there rose from the top of the mountain an enormous column of smoke, of a deep black, with white spots interspersed. The inhabitants, who had never before witnessed such a phenomenon, were struck with consternation. Soon, however, the co lumn fell down, and formed a species of arch over the volcano. +he falling in of the interior, under , mined by the previous discharge, is supposed to have 'been the cause of the tremendous sound, and of the ultimate opening of the crater.
This is, perhaps, the most active volcano in na ture. Since the Christian era, Etna has counted only twenty-seven eruptions ; and Vesuvius twenty four. But a resident at Bourbon assured our authot., that, from 1785 to 1802, the mountain had vomited flames at least twice every year, and eight of the streams had entered the sea. The lava, however, Scarcely ever issues from the summit of a crater, but from openings fir down the mountain, and sometimes almost on a level with the sea. It h remarkable, also, that earthquakes, which so gene rally desolate volcanic countries, are here unknown, or, at least, so slight, as to occasion no serious in Convenience. The constant channel of the subter raneous fire through the of the volcano, may, probably, be the chief cause which prevents it from shaking the surrounding regions. Another usual accompaniment, that of warm springs, is also wanting ; and none of the waters are impregnated with any species of gas. No petroleum has been
found, nor any metal, except iron.
Our traveller made next an excursion to the Piton des Neiges, which forms the summit of the Gros Monte highest mountain in the Island. This undertaking proved still more arduous. The season was favourable ; yet, when they were about half-way up, a prodigious rain came on ; and the road •lay through wet and swampy grounds, which were soon entirely covered with water. The mists became so thick, that 'nothing could be distinguish ed. The negroes, accustomed to a milder air, were benumbed ; and, refusing to proceed, would have perished with cold, had not the Frenchmen driven them forcibly on, till they came to a spot where they found shelter and refreshment. They spent here two nights ; and, on the third day, were able to reach their destination. The view from the summit appeared to our traveller to equal the most majestic scenes of the Alps and the Pyrenees. In the Island beneath, every object was visible as on a map; while, on every side, the immeasurable extent of ocean mingling with the skies. made them feel as if insulated on this spot from the rest of the universe. The thermometer was so low as 8°. Here consi derable masses of rock were observed, undermined to such a degree, that a very slight effort was suf ficient to throw them down the precipices, where, displacing others, they rolled to a great depth, and caused prodigious havock. Every part of the moun tain, indeed, appears furrowed and shattered by the violent action of the rains, which have already sen sibly diminished its magnitude, and are likely more and more to produce that effect.
M. Bory does not appear to have instituted any investigation into the height of these . mountains. Professor Jameson, in his Geognosy, estimates that of the Gros Marne at 9600, and that of the vol cano at 7680 feet above the level of the sea. The French traveller gives a copious, but not very pre cise, account of its geological features. The lower part of the Gros Moms is composed of basalt, a substance which abounds in every part of the Island, and which, from the manner in which it is connect ed with and surrounded by lava, is conceived by our author to have been universally crystallized from a state of fusion. He notices, also, the frequent oc currenee of what he calls Trappean lava; though this, m well as much of the basalt, would probably, by the disciple of Werner, be referred to some of the newer formations of Trap. On some of the pre cipices at the summit of the Gros Monte, there ap peared an immense depth of horizontal strata, which might have rendered an igneous origin improbable, had it not been so clearly proved by other phenome na. Large blocks of granite are found in the rivers which flow at the foot of the Gros Morse.