the fancy readily turns to it as a memorial of sorrow, on the grave of a city engulfed by the encroaching waters-the Novioregum of antiquity. A melancholy spectacle is presented farther north, towards Rochefort, that of flat barren wastes, and salt marshes, with here and there a spot planted with trees, and occasionally there is a village deserted and in ruins, high grass, and elder bushes mingling with its remains. It is hence with pleasure that the traveller descries the dome of the hospital and the walls of Rochefort; but, notwithstanding its fresh and smiling aspect, and the pleasant murmuring of its large elms, the town has been literally snatched, at an immense cost, from the morass, and no sooner is it passed than the dismal swamp again appears. The whole road to La Rochelle is of a melancholy character, and especially so if traversed under a cloudy sky. It crosses a dreary steppe, of which the sea is the limit on one hand, and which is apparently boundless on the other. At distant intervals are a few tamarind trees; or a lonely farm-house sends out its gloomy smoke; or some conical hay ricks are passed, standing round a neglected barn; or a meagre horse, with scanty mane, stands beside the road, and neighs at the approaching storm. The sea beats against the foundations of the road, and the sea-mews cross it, driven by the wind, their white wings contrasting strongly with the dark and louring clouds. Thus, at both extremities of the flat land of Europe, -the western, where it reaches the Atlantic, and the eastern, where it ends with the Caspian,-we find the same superficial aspect a monotonous, desolate, and treeless waste. CHAPTER IV. CAVERNS AND SUBTERRANEAN PASSAGES. HEN we reflect upon the manner in which the solid crust of the earth appears to have been formed, upon the powerful upheaving force by which its elevated sites have been raised, and the posterior agency of subterranean gases, volcanoes, and earthquakes, it is natural to expect chasms in the surface of tremendous depth, spaces also in the interior which have not been filled up with mineral masses similar to the materials of the earth itself, but by water, air, or vapour, with those cavities of grotesque and romantic appearance that are found in mountainous regions. There are few natural objects which have more awakened curiosity, or more strongly affected the imagination, than the hollow places, of various form and size, common in districts which have been subject to great physical disTheir seclusion and gloom-their fantastic architecture- the effect of torch-light upon their numerous crystallisations-the augmentation of sound and its reverberation together with their unknown extent in many cases-all these causes turbance. contribute to invest the cavities of the earth with exciting interest; nor is it strange to find them interwoven with the traditions and mythologies of unenlightened nations. On account of their sombre interior and strange outline being adapted to impose upon an ignorant populace, and give effect to religious observances, the priesthoods of antiquity localised in caverns their false divinities, and celebrated sanguinary rites upon the natural altars found in their recesses. A cave, with a priestess seated upon a tripod at its mouth, pretending to inhale a vapour from the interior which inspired a knowledge of future events, the gift of Apollo, was the original Delphian oracle, reverenced by the mind of Greece, and resorted to by the proudest monarchs of the ancient world. The cavern, along with the deep forest, commended itself to the primitive inhabitants of northern Europe by its mystery and gloom as an appropriate spot for the performance of a barbarous worship, and many local titles of such sites preserve the memory of their former uses. An instance of this we have in Thor's cave, or, as Darwin calls it, "The blood-smear'd mansion of gigantic Thor," a broad excavation on the face of a huge rock in the limestone district of Derbyshire, divided into two chambers, one beyond the other, with a detached stone at the further extremity, where the light of day is very much subdued. But in India the largest use has been made of caverns for religious purposes, and immense pains have been taken with their adornment, extension, and architecture, at Elephanta, Salsette, and Ellora, where there are elaborately wrought temples constructed, probably out of small natural crevices in the rock. We shall now refer to a few of those cavities which are entirely the workmanship of nature, with whose form man has not intermeddled, and notice the principal phenomena which they exhibit. That extensive cavities exist in the interior of the crust of the globe is evident from the phenomena of volcanoes and earthquakes. They are not accessible to observation, but the repeated tremblings of the soil in various places, and experiments made of oscillations of the pendulum, point to the conclusion, that there are large underlying hollows, at no great distance from the surface, of which the superficial land forms the Jorullo, Mexico. roof. The table-land of Quito, surrounded by the most powerful volcanoes upon the earth, and the remarkable plain of Jorullo, are supposed to be examples of this. Condamine believed that a considerable portion of the former district was to be regarded as the dome of an enormous vault; and Parrot has shown it to be highly probable, by a careful calculation, that a cavity of at least a cubic mile and a half exists beneath its surface. The rumbling noise, like that of distant thunder, which on the testimony of Humboldt usually precedes and accompanies the eruption of its volcanoes, affords evidence in favour of this sup position, and as an increase of the subterranean vacuity must be the necessary consequence of every outbreak, it is not at all an improbable event, that the blooming landscape will ultimately fall in, and this piece of table-land become an immense depression. The quantity of material scooped out of the interior of the earth by volcanic action is immense, and calculated to produce vacuities in which the largest mountains would have ample space. It has been estimated that Etna in one of its last most important eruptions, that of the year 1769, threw out a mass of lava equal in volume to a cone 5820 feet in height, and 11,640 feet in breadth, or nearly four times larger than Vesuvius. Fourteen such eruptions would produce a mass equal to Mont Blanc, reckoning from the level of the sea, and twenty-six such large eruptions have occurred since the twelfth century. In the year 1783, when the earthquake of Calabria occurred, the Skaptar volcano in Iceland poured forth a stream of lava fifty miles long, between twelve and fifteen broad, and from one to six hundred feet in thickness, which must have been equal to six times the mass of Mont Blanc, and two and a half times that of Chimboraço. From the discovery of America to the year 1759, the plain of Malpais, a volcanic district in Mexico, had remained undisturbed, and was covered with plantations of indigo and sugar-cane at the latter period. In the month of June, a succession of earthquakes commenced, and on the night of September the 28th a tract not less than from three to four miles in extent rose up in the shape of a dome; and six great masses suddenly appeared, having an elevation of from 1312 to 1640 feet above the original level of the plain. The most elevated of these is the volcano of Jorullo, which is continually burning, the projection of which, with its kindred masses, must have created a considerable subterranean vacuity, and probably the whole dome-shaped plain of Malpais is hollow. Hence, it is a common event, in countries subject to great volcanic activity, for portions of the surface to fall in, the subsidence frequently becoming the bed of a lake. A part of the forest of Aripas in the Caraccas thus subsided in the year 1790; a lake was formed nearly half a mile in diameter, and from eighty to a hundred yards in depth, and for several months after the trees of the forest remained green under the water. In the same year, in Sicily, at Santa Maria de Nisremi, a portion of the country three Italian miles in circumference sank thirty feet deep. Occurrences of the same kind appear to take place in the depth of the sea, the falling in of its bed being indicated on the surface of the waters by their sudden retreat and violent agitation on their return. A remarkable example of this phenomenon took place at Marseilles, on June 28, 1812, when the water in the harbour suddenly sank, then rushed out with great rapidity, and returned with equal violence; a movement which was repeated several times, till the equilibrium was restored, occasioning considerable damage to the shipping. Instances of similar events are innumerable, which serve to prove the existence of cavities, both in the interior of the exposed crust of the earth, and those parts of it over which the ocean rolls. To Humboldt we are indebted for a large amount of information respecting the cavities which appear upon the surface, the chief differences of their form, the beds in which they are found, and the causes which may have originated them. In the primary rocks, caverns are relatively fewer than in the later deposits, while the oldest masses of the granite and gneiss formations are particularly destitute of them. The principal are wide fissures, sometimes of unknown depth, and those hollow passages which occur in Switzerland and Dauphiné, called crystal caves, owing to their walls being richly furnished with pillars of rock crystal. Similar vacuities occur in the gneiss of the Pine mountain in the neighbourhood of Wiesenthal, but they are not important. In Sweden and Norway, the granite presents fissures and caves of extraordinary extent, and perfectly unexplored, hitherto; such as the cave of Marienstadt, the end of which is not known, and the enormous deep hole at Frederick stall, where a stone thrown in only gives the echo of its fall in a minute and a half or two minutes; an observation which, if well founded, would give, on the calculation of Perrit, a precipitous depth of 59,049 feet, the highest estimate, or 39,866 feet, the least; that is, from twice to three times the height of Chimboraço. It is the primitive limestone that supplies the most numerous examples of caves and grottos in the primary rocks; and if these yield in point of size to the later limestone formations, this arises from the inferior extent of the primitive limestone, rather than from its incapacity to form caves. In the transition mountains, and those of stratified structure, it is still the limestone in which the more extensive caves are found, of which those of the Hartz, the splendid caverns of Derbyshire, and those of the Carpathians, are well known. Caverns most frequently occur in the mountains of stratified limestone; and among these, one of the most modern formations, the Jura limestone, is particularly distinguished, and was therefore termed the cavern-limestone by the early geologists. The celebrated caves of Franconia, the grotto of Notre Dame between Grenoble and Lyons, and many others, occur in this formation. That of Kirkdale, in Yorkshire, is in oolitic strata. Next to the limestone in the stratified formations, the so-called older gypsum which contains salt is the most abundant in caverns. They are of rare occurrence in the sandstone, have generally broad openings but of no great extent. Such are the Cow-stall in Saxony, and a few caves in Bohemia. In the volcanic rocks, cavern formations are very common, and one of the most splendid examples in the world occurs in the basalt, a rock of comparatively modern igneous origin. This is the well-known cave of Fingal, in the island of Staffa, a small island on the western coast of Scotland, composed entirely of amorphous and pillared basalt. The name of the island is derived from its singular structure, Staffa signifying, in the Norwegian language, a people who were early on this coast, a staff, and, figuratively, a column. The basaltic columns have in various places yielded to the action of the waves, which have scooped out caves of the most picturesque description, the chief of which are the Boat cave, the Cormorant cave, so called from the number of these birds visiting the spot, and the great cave of Fingal. It is remarkable that this grand natural object should have remained comparatively unknown, until Sir Joseph Banks had his attention accidentally directed to it, and may be said to have discovered it to the inhabitants of South Britain. This great cavern consists of a lava-like mass at the base, and of two ranges of basaltic columns resting upon it, which present to the eye an appearance of regularity almost architectural, and supporting an irregular ceiling of rock. According to the measurements of Sir Joseph Banks, the cave from the rock without is 371 feet 6 inches; the breadth at the mouth, 53 feet 7 inches; the height of arch at the mouth, 117 feet 6 inches; depth of water at the mouth, 18 feet; and at the bottom of the cave, 9 feet. The echo of the waves which wash into the cavern has originated its Gaelic name, Llaimh-binn, the Cave of Music. Macculloch remarks: "If too much admiration has been lavished on it by some, and if, in consequence, more recent visitors have left it with disappointment, it must be recollected, that all descriptions are but pictures of the feelings of the narrator; it is, moreover, as unreasonable to expect that the same objects should produce corresponding effects on all minds, on the enlightened and on the vulgar, as that every individual should alike be sensible of the merits of Phidias and Raphael, of Sophocles and of Shakespeare. But if this cave were even destitute of that order and symmetry, that richness arising from multiplicity of parts combined with greatness of dimension and simplicity of style, which it possesses; still the prolonged length, the twilight gloom half concealing the playful and varying effects of reflected Cave of Fingal. P light, the echo of the measured surge as it rises and falls, the transparent green of the water, and the profound and fairy solitude of the whole scene, could not fail strongly to impress a mind gifted with any sense of beauty in art or in nature, and it will be compelled to own it is not without cause that celebrity has been conferred on the Cave of Fingal." Caverns occur in modern porphyry in the neighbourhood of Quito, and even in modern lavas, the ejection of which has taken place within the memory of man. Flinders has made us acquainted with caves in the lava of the Isle of France; and in the lava of Vesuvius of 1805, Gay Lussac found several upon a small scale. But caverns of an enormous extent occur in the lava of Iceland, that of Gurtshellir, situated in the torrent which has flowed from Bald Yökul, being forty feet in height, by fifty in breadth, and nearly a mile in length. Beautiful black volcanic stalactites hang from the high and spacious vault, and the sides present a succession of vitrified horizontal stripes, a thick coating of ice clear as crystal covering the floor. Henderson, in particular, describes one spot, the grandeur of which surpassed all expectation, the light of the torches rendering it peculiarly enchanting. The roof and sides of the cave were decorated with the most superb icicles, crystallized in every possible form, many of which rivalled in minuteness the finest zeolites; while from the icy floor rose pillars of the same substance, assuming all the curious and fantastic shapes imaginable, mocking the proudest specimens of art, and counterfeiting many well-known objects of animated nature. A more brilliant scene, says Henderson, perhaps never presented itself to the human eye, nor was it easy for us to divest ourselves of the idea that we actually beheld one of the fairy scenes depicted in Eastern fable. Among the forms under which caverns present themselves, Humboldt distinguishes three principal kinds, which essentially differ from each other, notwithstanding all their apparent irregularities. The first appear in the form of cracks or fissures, like empty veins of ore, of greater or less extent, but narrow and considerably prolonged, often penetrating far into the hard rock, and only reaching the day at one end. Eldon hole, in the Peak of Derbyshire, is an example of this class. This is a deep yawning chasm in the limestone strata, but no longer considered one of the wonders of the region, as its presumed unfathomable depths have been satisfactorily measured. In the reign of Queen Elizabeth, the Earl of Leicester is said to have hired a man to go down into it to ascertain its extent and form. The account of the adventure states, that he was let down about two hundred ells, and after he had remained at the length of the rope awhile, he was drawn up again, with great expectation of some discoveries; but he came up senseless, and died within eight days in a phrensied condition. Cotton alludes to this circumstance in his rude English verses, "Once a mercenary fool, 'tis said, exposed Of stranger sights than Theseus saw in hell; He lived eight days, and then the world forsook." Eldon Hole is a fissure about sixty feet long, twenty wide, and two hundred deep. In the Philosophical Transactions for the year 1781, there is an account of the descent of Mr. Lloyd, who was let down with a rope by eight men, and found the light sufficiently strong at the bottom to allow him to read print. He discovered a fissure in the rock at the bottom, through which a strong current of air proceeded, but as the aperture was nearly filled up with huge stones, he could not examine it. A former owner of the |