valleys, sometimes filling them up with its volume, and burying man, beast, and village beneath its load. The avalanches composed simply of drifts, are not so dangerous and destructive as those of snow rendered clammy by a thaw. The former may frequently be removed without much damage being sustained, but the latter are precipitated in compact masses, and carry away or crush the objects that lie in their path. In the canton of the Grisons, an avalanche descended in the year 1749, upon the valley of Tawich, and entirely covered the whole village of Rueras. The snow torrent fell in the night without disturbing some of the inhabitants, who, on awaking in the morning, were surprised that the day did not break; — sixty out of a hundred persons were rescued from their perilous situation alive, a sufficient quantity of air to support life being obtained through interstices in their snowy canopy. In the same canton, an avalanche descended upon Val Calanca in 1806, which removed a forest from its site to an opposite side of the valley, and fixed a fir-tree upon the roof of the parsonage house. Avalanches occur in the Pyrenees and in Norway, but are most frequent in the high Alps owing to their abrupt and precipitous declivities. They are often set in motion by vibrations of the air, such as the discharge of a musket, or a peal of thunder, or the mere passage of a traveller will produce it; and hence in districts subject to them a cautious silence and wary footsteps are enjoined upon the inexperienced visitor. Professor Forbes gives a striking instance of encountering a highly electrical condition of the atmosphere, when at a considerable elevation in the Alps: "We were still above 9000 feet above the sea, when I noticed a curious sound which seemed to proceed from the Alpine pole with which I was walking. I asked the guide next me whether he heard it, and what he thought it was. The members of that fraternity are very hard pushed indeed, when they have not an answer ready for any emergency. He therefore replied with great coolness, that the rustling of the stick proceeded from a worm eating the wood in the interior. This answer did not appear to me satisfactory, and I therefore applied the experimentum crucis of reversing the stick, so that the point was now uppermost. The worm was already at the upper end. I next held my hand above my head, and my fingers yielded a fizzing sound. There could be but one explanationwe were so near a thunder cloud as to be highly electrified by induction. I soon perceived that all the angular stones were hissing round us like points near a powerful electrical machine. I told my companions of our situation, and begged Damatter to lower his umbrella, which he had hoisted against a hail shower, and whose gay brass point was likely to become the paratonnerre of the party. The words were scarcely out of my mouth when a clap of thunder, unaccompanied by lightning, justified my precaution." The thunder clap, the hunter's horn, or even the human voice, has frequently shook the nicely poised avalanche from its site, and hurled it into lower regions, crushing trees, sweeping away rocks, and damming up the streams that have lain in its course. Besides accumulations of snow, we meet with glaciers in high regions, or extensive fields of ice. These are formed from the snow-fields, partially thawed and subsequently frozen. The water yielded by the melting of the surface, in connection with rain, percolates through the mass, which acquires consistency, and is converted into compact ice by a depressed temperature. Iceland is appropriately named from the number and extent of its glaciers, which are there known by the name of Yokuls, signifying large masses of ice. The most extensive, the Klofa Yokul, in the eastern quarter of the island, is a vast chain of ice and snow mountains, supposed to fill a space of not less than three thousand square miles. Some of the Yokuls are remarkable for their vacillation, not remaining in a settled position, a peculiarity common to the Alpine glaciers. These ice formations are found among the Norwegian highlands, in the chain of the Pyrenees, upon the Sierra Nevada of Spain; but their grand European site is the Alps. "If," says Saussure, "a spectator could be placed at a sufficient height above the Alps, to embrace at one view those of Switzerland, Savoy, and Dauphiné, he would see a mass of mountains intersected by numerous valleys, and composed of several parallel chains, the highest in the middle, and the others decreasing gradually as they recede. The central and highest chain would appear to him bristled with craggy rocks, covered, even in summer, with snow and ice in all those places that are not absolutely vertical; but on both sides of the chain, he would see deep and verdant valleys, well watered and covered with villages. Examining still more in detail, he would remark that the central range is composed of lofty peaks and smaller chains, covered with snow on their tops, but having all their slopes that are not very much inclined, covered with ice, while the intervals between them form elevated valleys filled with immense masses of ice, extending down into the deep and inhabited valleys which border on the great chain. The chain nearest to the centre would present to the observer the same phenomenon, but on a smaller scale, beyond which he would see no more ice, nor even snow, save here and there on some of the more elevated summits." Saussure therefore recognised two kinds of glaciers; the first contained in the valleys, more or less deep, and which, though at great elevations, are still commanded on all sides by mountains higher still; the second not contained in valleys, but spread out on the slopes of the higher peaks. The glacier system of the Alps embraces an extensive area. M. Ebel estimates, that there may be at least four hundred of the larger sized glaciers, or varying from three to thirty miles in length. The aggregate superficial extent of all those of the Tyrol, Switzerland, Piedmont, and Savoy, is calculated by some authorities to amount to not less than fourteen hundred square miles. The greatest breadth of an individual specimen is seldom more than two miles. The thickness varies from a hundred to six hundred feet. The glaciers are moving masses, urged down the inclined planes upon which they are situate by the mutual pressure of their parts, a movement which the seasons accelerate or retard according to their character. This motion gives rise to the extraordinary spectacle, of summer productions and winter formations being sometimes in immediate contact with each other, the ice-fields obtruding into flowery meadows, and gradually forcing their way into the regions of cultivation. According to Professor Forbes, the very huts of the peasantry are sometimes invaded by this moving ice, and many persons now living have seen the full ears of corn touching the glacier, or gathered ripe cherries from the trees with one foot standing on the ice! The rate of advance of different glaciers varies considerably. M. Ebel states, that in the valley of Chamouni, they travel at about fourteen feet a year, while in that of Grindelwald, the glaciers move rather faster, at the rate of twenty-five feet in a year, a difference probably attributable to the ground being variously inclined. The same glacier will also make more progress in one year than in another, according as a summer of lesser or greater warmth renders its liberation more or less complete. Captain Hall remarks upon the ploughing up of the ground lying before a glacier by its snout as an obvious proof of its progression, and instances the remarkable case of the glacier of Brenva falling into the lower part of the Allée Blanche, fairly crossing from one side of the valley to the other, and being so irresistibly pressed forward by the weight of snow on its shoulders, high up the sides of Mont Blanc, that on reaching the opposite side of the valley, it actually travels for a considerable distance up the bank. "The guides," he remarks, "pointed out the corners of green fields, peeping out from the sides of the glacier in the middle of the valley, and showed us traces of walls and fences which had belonged to large villages, now entirely obliterated by the moving mass. I took notice of one circumstance, which told the fatal story very well. We had walked along a well-worn footpath till our course was abruptly stopped by the edge of the glacier; but on crossing over it, we re-discovered our footpath, which had been quite hidden by the intervening mass." There is a limit, however, put to the encroachments of the glaciers. The lower extremities are gradually thawed away in the warm atmosphere of the valleys, so that though pushed forward by the weight of ice and snow accumulated at the upper extremities during the winter, there is a "bound fixed by a perpetual decree," beyond which they cannot pass. Coleridge strikingly alludes to these formations in his Hymn before Sunrise in the Vale of Chamouni; and science will not quarrel with him for the line which expresses the optical appearance, rather than the philosophical truth. "Ye ice-falls! ye that from the mountain's brow Who made you glorious as the gates of heaven And in their perilous fall shall thunder, God!" The glaciers exhibit a singularly diversified aspect, hues varying from the purest white to a blue and green tinge, surfaces resembling in some parts a smooth and polished mirror, and in others a sea frozen when angry and tempest-tost. But of all the phenomena exhibited by the highlands of the globe, those of the active volcanoes are the most peculiar and sublime. The term is derived from Vulcanus, the imaginary god of fire among the Romans, and is applied to those mountains which are the vents of igneous action, ejecting from their sides or summits flame, smoke, ashes, and lava streams. They are in general elevations of a conical form, terminating at the summit with a hollow, called a crater or cup from its shape. Smoke is constantly issuing from the tops of some of these mountains, but the violent paroxysms during which stones are discharged, and torrents of red-hot lava, occur only at distant and irregular intervals. The eruptions frequently issue from several openings or smaller craters, within the superior one, the number and size of which are considerably varied by eras of disturbance. These eras are generally preceded, in some instances for several weeks, by the shocks of earthquakes, or by immense columns of smoke issuing from the volcano about to exhibit explosion, often involving the neighbouring country in darkness. Sounds resembling the successive discharges of a park of artillery are then heard, followed by sudden flashes of flame, and showers of stones. A stream of lava next bursts forth from the side of the mountain, or in a great eruption from the crater, flowing in a sluggish fiery current down the declivities. After the lava ceases to flow, the volcanic ashes, composed of various materials, are thrown out of the summit in immense quantities, sufficient to cover the vicinity for miles. The products of volcanoes differ to some extent, those of America casting out water, and in some instances fish, besides the ordinary materials. It is singular, also, that in the New World, the active volcanic sites are chiefly continental, while in the Old World they are mostly found in the islands. In both regions, however, they are almost invariably situated near the sea, or some inland collection of water. Upwards of three hundred are known to exist, distributed as follows, according to Girardin's table, which, however, is only approximative: N In addition to the above, Mount Erebus, on the south polar continent, is an active volcano of immense size. The mass and elevation of volcanoes seem to regulate the occurrence of eruptions, the smallest being the most active. Thus Stromboli, an inferior elevation, is almost always flaring as the great lighthouse of nature in the Mediterranean. Vesuvius, far less than Etna, is the most active of the two, while some of the enormous Andean cones repose for centuries. Of existing volcanic action, the most sublime and imposing example perhaps to be found in the world, is in the island of Hawaii, formerly called Owhyhee. The whole island seems to be an immense hollow cone, having an area of 4000 square miles, and attaining an elevation of 16,000 feet, the height of Mowna Roa. It forms a pyramidal chimney over a vast incandescent mass burning beneath it, and also under some part of the bed of the surrounding ocean, having numerous vents through which the furnace below communicates with the atmosphere above. Lord Byron and a party of officers from the Blonde frigate, with the Rev. Mr. Stewart, visited the crater of Kilauea, near the base of Mowna Roa, and witnessed a scene, says the describer, more horribly sublime than any thing he had ever imagined to exist even in the idler visions of unearthly things. Arrived at the brink of the crater, they stood looking down into a fearful gulph, fifteen hundred feet in depth, and upwards of two miles in circumference. The edge of the crater was so steep, that it seemed as if by a single leap they could plunge into the lowest abyss. Its surface had all the agitation of an ocean. Billow after billow tossed its monstrous bosom into the air, and occasionally the waves from opposite directions met with such violence as to dash the fiery spray in the concussion forty or fifty feet high. Such was the agonising struggle of the action within-the appalling sounds of the conflicting elements, muttering and sighing, groaning and blowing, that one of the party shrunk back exclaiming:- "Call it weakness, or whatever you please, but I cannot look again!" About fifty cones of various height, active chimneys of volcanic fire, were counted in the abyss. Volumes of smoke and steam were ascending from these vents, but as the evening closed, fire after fire appeared glimmering through the vapour. Some of the cones were ejecting fragments of rock; others, ashes, lava, and boiling water; streams of fire seemed to be running among the labouring craters; forming a scene which, in connexion with the roar of the elements bursting from their prison, reminded the party, as one of them expressed it, of the lake that burneth with fire and brimstone. To the bottom of the abyss it is well known that a Christian convert descended, and plunged a stick into the fiery deluge! an act of female heroism to dispel the illusion of her countrymen, who were spectators at a distance, and who fancied that Peli, the god of the Kilauea fires, would punish with instant destruction any violation of his sanctuary. One of the most tremendous volcanic eruptions ever recorded, was that which issued from the Tomboro mountain in the island of Sumbawa, for an account of which we are indebted to Sir Stamford Raffles. It began on the 5th of April, 1815, and continued with some intermissions until the June following. The sound of the explosion was heard at Ternate on the western coast of Gilolo, a distance of seven hundred and twenty geographical miles: and in Sumatra, which is nine hundred and seventy. In some parts of the island violent whirlwinds carried up men, horses, and cattle into the air; the sea was covered with the trunks of trees which had been torn up; and the ashes from the mountain, wafted to Tara and Celebes, a distance of three hundred miles, caused a darkness in the daytime more profound than had ever been known in the darkest night. To the west |