stay at tenerife. journey from santa cruz to orotava. excursion to the summit of the peak of teyde.

from the time of our departure from graciosa, the horizon continued so hazy, that, notwithstanding the considerable height of the mountains of canary,* we did not discover that island till the evening of the 18th of june. it is the granary of the archipelago of the fortunate islands; and, what is very remarkable in a region situated beyond the limits of the tropics, we were assured, that in some districts, there are two wheat harvests in the year; one in february, and the other in june. canary has never been visited by a learned mineralogist; yet this island is so much the more worthy of observation, as the physiognomy of its mountains, disposed in parallel chains, appeared to me to differ entirely from that of the summits of lancerota and teneriffe. nothing is more interesting to the geologist, than to observe the relations, on the same point of the globe, between volcanic countries, and those which are primitive or secondary. when the canary islands shall have been examined, in all the parts which compose the system of these mountains, we shall find that we have been too precipitate in considering the whole group as raised by the action of submarine fires.

[* isla de la gran canaria.]

on the morning of the 19th, we discovered the point of naga, but the peak of teneriffe was still invisible: the land, obscured by a thick mist, presented forms that were vague and confused. as we approached the road of santa cruz we observed that the mist, driven by the winds, drew nearer to us. the sea was strongly agitated, as it most commonly is in those latitudes. we anchored after several soundings, for the mist was so thick, that we could scarcely distinguish objects at a few cables’ distance; but at the moment we began to salute the place, the fog was instantly dispelled. the peak of teyde appeared in a break above the clouds, and the first rays of the sun, which had not yet risen on us, illumined the summit of the volcano.

we hastened to the prow of the vessel to behold the magnificent spectacle, and at the same instant we saw four english vessels lying to, and very near our stern. we had passed without being perceived, and the same mist which had concealed the peak from our view, had saved us from the risk of being carried back to europe. the pizarro stood in as close as possible to the fort, to be under its protection. it was on this shore, that, in the landing attempted by the english two years before our arrival, in july 1797, admiral nelson had his arm carried off by a cannon-ball.

the situation of the town of santa cruz is very similar to that of la guayra, the most frequented port of the province of caraccas. the heat is excessive in both places, and from the same causes; but the aspect of santa cruz is more gloomy. on a narrow and sandy beach, houses of dazzling whiteness, with flat roofs, and windows without glass, are built close against a wall of black perpendicular rock, devoid of vegetation. a fine mole, built of freestone, and the public walk planted with poplars, are the only objects which break the sameness of the landscape. the view of the peak, as it presents itself above santa cruz, is much less picturesque than that we enjoy from the port of orotava. there, a highly cultured and smiling plain presents a pleasing contrast to the wild aspect of the volcano. from the groups of palm trees and bananas which line the coast, to the region of the arbutus, the laurel, and the pine, the volcanic rock is crowned with luxuriant vegetation. we easily conceive how the inhabitants, even of the beautiful climates of greece and italy, might fancy they recognised one of the fortunate isles in the western part of teneriffe. the eastern side, that of santa cruz, on the contrary, is every where stamped with sterility. the summit of the peak is not more arid than the promontory of basaltic lava, which stretches towards the point of naga, and on which succulent plants, springing up in the clefts of the rocks, scarcely indicate a preparation of soil. at the port of orotava, the top of the piton subtends an angle in height of more than eleven degrees and a half; while at the mole of santa cruz* the angle scarcely exceeds 4° 36′.

[* the oblique distances from the top of the volcano to orotava and to santa cruz are nearly 8600 toises and 22,500 toises.]

notwithstanding this difference, and though in the latter place the volcano rises above the horizon scarcely as much as vesuvius seen from the mole of naples, the aspect of the peak is still very majestic, when those who anchor in the road discern it for the first time. the piton alone was visible to us; its cone projected itself on a sky of the purest blue, whilst dark thick clouds enveloped the rest of the mountain to the height of 1800 toises. the pumice-stone, illumined by the first rays of the sun, reflected a reddish light, like that which tinges the summits of the higher alps. this light by degrees becomes dazzlingly white; and, deceived like most travellers, we thought that the peak was still covered with snow, and that we should with difficulty reach the edge of the crater.

we have remarked, in the cordillera of the andes, that the conical mountains, such as cotopaxi and tungurahua, are oftener seen free from clouds, than those of which the tops are broken into bristly points, like antisana and pichincha; but the peak of teneriffe, notwithstanding its pyramidical form, is a great part of the year enveloped in vapours, and is sometimes, during several weeks, invisible from the road of santa cruz. its position to the west of an immense continent, and its insulated situation in the midst of the sea, are no doubt the causes of this phenomenon. navigators are well aware that even the smallest islets, and those which are without mountains, collect and harbour the clouds. the decrement of heat is also different above the plains of africa, and above the surface of the atlantic; and the strata of air, brought by the trade winds, cool in proportion as they advance towards the west. if the air has been extremely dry above the burning sands of the desert, it is very quickly saturated when it enters into contact with the surface of the sea, or with the air that lies on that surface. it is easy to conceive, therefore, why vapours become visible in the atmospherical strata, which, at a distance from the continent, have no longer the same temperature as when they began to be saturated with water. the considerable mass of a mountain, rising in the midst of the atlantic, is also an obstacle to the clouds, which are driven out to sea by the winds.

on entering the streets of santa cruz, we felt a suffocating heat, though the thermometer was not above twenty-five degrees. those who have for a long time inhaled the air of the sea suffer every time they land; not because this air contains more oxygen than the air on shore, as has been erroneously supposed, but because it is less charged with those gaseous combinations, which the animal and vegetable substances, and the mud resulting from their decomposition, pour into the atmosphere. miasms that escape chemical analysis have a powerful effect on our organs, especially when they have not for a long while been exposed to the same kind of irritation.

santa cruz, the anaza of the guanches, is a neat town, with a population of 8000 souls. i was not struck with the vast number of monks and secular ecclesiastics, which travellers have thought themselves bound to find in every country under the spanish government; nor shall i stop to enter into the description of the churches; the library of the dominicans, which contains scarcely a few hundred volumes; the mole, where the inhabitants assemble to inhale the freshness of the evening breeze; or the famed monument of carrara marble, thirty feet high, dedicated to our lady of candelaria, in memory of the miraculous appearance of the virgin, in 1392, at chimisay, near guimar. the port of santa cruz may be considered as a great caravanserai, on the road to america and the indies. every traveller who writes the narrative of his adventures, begins by a description of madeira and teneriffe; and if in the natural history of these islands there yet remains an immense field untrodden, we must admit that the topography of the little towns of funchal, santa cruz, laguna, and orotava, leaves scarcely anything untold.

the recommendation of the court of madrid procured for us, in the canaries, as in all the other spanish possessions, the most satisfactory reception. the captain-general gave us immediate permission to examine the island. colonel armiaga, who commanded a regiment of infantry, received us into his house with kind hospitality. we could not cease admiring the banana, the papaw tree, the poinciana pulcherrima, and other plants, which we had hitherto seen only in hot-houses, cultivated in his garden in the open air. the climate of the canaries however is not warm enough to ripen the real platano arton, with triangular fruit from seven to eight inches long, and which, requiring a temperature of 24 centesimal degrees, does not flourish even in the valley of caracas. the bananas of teneriffe are those named by the spanish planters camburis or guineos, and dominicos. the camburi, which suffers least from cold, is cultivated with success even at malaga, where the temperature is only 18°; but the fruit we see occasionally at cadiz comes from the canary islands by vessels which make the passage in three or four days. in general, the musa, known by every people under the torrid zone, though hitherto never found in a wild state, has as great a variety of fruit as our apple and pear trees. these varieties, which are confounded by the greater part of botanists, though they require very different climates, have become permanent by long cultivation.

we went to herborize in the evening in the direction of the fort of passo alto, along the basaltic rocks that close the promontory of naga. we were very little satisfied with our harvest, for the drought and dust had almost destroyed vegetation. the cacalia kleinia, the euphorbia canariensis, and several other succulent plants, which draw their nourishment from the air rather than the soil on which they grow, reminded us by their appearance, that this group of islands belongs to africa, and even to the most arid part of that continent.

though the captain of the pizarro had orders to stop long enough at teneriffe to give us time to scale the summit of the peak, if the snows did not prevent our ascent, we received notice, on account of the blockade of the english ships, not to expect a longer delay than four or five days. we consequently hastened our departure for the port of orotava, which is situated on the western declivity of the volcano, where we were sure of finding guides. i could find no one at santa cruz who had mounted the peak, and i was not surprised at this. the most curious objects become less interesting, in proportion as they are near to us; and i have known inhabitants of schaffhausen, in switzerland, who had never seen the fall of the rhine but at a distance.

on the 20th of june, before sunrise, we began our excursion by ascending to the villa de laguna, estimated to be at the elevation of 350 toises above the port of santa cruz. we could not verify this estimate of the height, the surf not having permitted us to return on board during the night, to take our barometers and dipping-needle. as we foresaw that our expedition to the peak would be very precipitate, we consoled ourselves with the reflection that it was well not to expose instruments which were to serve us in countries less known by europeans. the road by which we ascended to laguna is on the right of a torrent, or baranco, which in the rainy season forms fine cascades; it is narrow and tortuous. near the town we met some white camels, which seemed to be very slightly laden. the chief employment of these animals is to transport merchandise from the custom-house to the warehouses of the merchants. they are generally laden with two chests of havannah sugar, which together weigh 900 pounds; but this load may be augmented to thirteen hundred-weight, or 52 arrobas of castile. camels are not numerous at teneriffe, whilst they exist by thousands in the two islands of lancerota and forteventura; the climate and vegetation of these islands, which are situated nearer africa, are more analogous to those of that continent. it is very extraordinary, that this useful animal, which breeds in south america, should be seldom propagated at teneriffe. in the fertile district of adexe only, where the plantations of the sugar-cane are most considerable, camels have sometimes been known to breed. these beasts of burden, as well as horses, were brought into the canary islands in the fifteenth century by the norman conquerors. the guanches were previously unacquainted with them; and this fact seems to be very well accounted for by the difficulty of transporting an animal of such bulk in frail canoes, without the necessity of considering the guanches as a remnant of the people of atlantis, or a different race from that of the western africans.

the hill, on which the town of san christobal de la laguna is built, belongs to the system of basaltic mountains, which, independent of the system of less ancient volcanic rocks, form a broad girdle around the peak of teneriffe. the basalt on which we walked was darkish brown, compact, half-decomposed, and when breathed on, emitted a clayey smell. we discovered amphibole, olivine,* and translucid pyroxenes, * with a perfectly lamellar fracture, of a pale olive green, and often crystallized in prisms of six planes. the first of these substances is extremely rare at teneriffe; and i never found it in the lavas of vesuvius; but those of etna contain it in abundance. notwithstanding the great number of blocks, which we stopped to break, to the great regret of our guides, we could discover neither nepheline, leucite,* nor feldspar. this last, which is so common in the basaltic lavas of the island of ischia, does not begin to appear at teneriffe, till we approach the volcano. the rock of laguna is not columnar, but is divided into ledges, of small thickness, and inclined to the east at an angle of 30 or 40°. it has nowhere the appearance of a current of lava flowing from the sides of the peak. if the present volcano has given birth to these basalts, we must suppose, that, like the substances which compose the somma, at the back of vesuvius, they are the effect of a submarine effusion, in which the liquid mass has formed strata. a few arborescent euphorbias, the cacalia kleinia, and indian figs (cactus), which have become wild in the canary islands, as well as in the south of europe and the whole continent of africa, are the only plants we see on these arid rocks. the feet of our mules were slipping every moment on beds of stone, which were very steep. we nevertheless recognized the remains of an ancient pavement. in these colonies we discover at every step some traces of that activity which characterized the spanish nation in the 16th century.

[* peridot granuliforme. hauy.]

[* augite. — werner.]

[* amphigene. — hauy.]

as we approached laguna, we felt the temperature of the atmosphere gradually become lower. this sensation was so much the more agreeable, as we found the air of santa cruz very oppressive. as our organs are more affected by disagreeable impressions, the change of temperature becomes still more sensible when we return from laguna to the port: we seem then to be drawing near the mouth of a furnace. the same impression is felt, when, on the coast of caracas, we descend from the mountain of avila to the port of la guayra. according to the law of the decrement of heat, three hundred and fifty toises in height produce in this latitude only three or four degrees difference in temperature. the heat which overpowers the traveller on his entrance into santa cruz, or la guayra, must consequently be attributed to the reverberation from the rocks, against which these towns are built.

the perpetual coolness which prevails at laguna causes it to be considered in the canaries a delightful abode. situated in a small plain, surrounded by gardens, protected by a hill which is crowned by a wood of laurels, myrtle, and arbutus, the capital of teneriffe is very beautifully placed. we should be mistaken if, relying on the account of some travellers, we believed it seated on the border of a lake. the rain sometimes forms a sheet of water of considerable extent; and the geologist, who beholds in everything the past rather than the present state of nature, can have no doubt but that the whole plain is a great basin dried up. laguna has fallen from its opulence, since the lateral eruptions of the volcano have destroyed the port of garachico, and since santa cruz has become the central point of the commerce of the island. it contains only 9000 inhabitants, of whom nearly 400 are monks, distributed in six convents. the town is surrounded with a great number of windmills, which indicate the cultivation of wheat in these high countries. i shall observe on this occasion, that different kinds of grain were known to the guanches. they called wheat at teneriffe tano, at lancerota triffa; barley, in the grand canary, bore the name of aramotanoque, and at lancerota it was called tamosen. the flour of roasted barley (gofio) and goat’s-milk constituted the principal food of the people, on the origin of which so many systematic fables have been current. these aliments sufficiently prove that the race of the guanches belonged to the nations of the old continent, perhaps to those of caucasus, and not like the rest of the atlantides,* to the inhabitants of the new world; these, before the arrival of the europeans, were unacquainted with corn, milk, and cheese.

[* without entering here into any discussion respecting the existence of the atlantis, i may cite the opinion of diodorus siculus, according to whom the atlantides were ignorant of the use of corn, because they were separated from the rest of mankind before these gramina were cultivated.]

a great number of chapels, which the spaniards call ermitas, encircle the town of laguna. shaded by trees of perpetual verdure, and erected on small eminences, these chapels add to the picturesque effect of the landscape. the interior of the town is not equal to its external appearance. the houses are solidly built, but very antique, and the streets seem deserted. a botanist ought not to complain of the antiquity of the edifices. the roofs and walls are covered with canary house-leek and those elegant trichomanes, mentioned by every traveller. these plants are nourished by the abundant mists.

mr. anderson, the naturalist in the third voyage of captain cook, advises physicians to send their patients to teneriffe, on account of the mildness of the temperature and the equal climate of the canaries. the ground on these islands rises in an amphitheatre, and presents simultaneously, as in peru and mexico, the temperature of every climate, from the heat of africa to the cold of the higher alps. santa cruz, the port of orotava, the town of the same name, and that of laguna, are four places, the mean temperatures of which form a descending series. in the south of europe the change of the seasons is too sensibly felt to present the same advantages. teneriffe, on the contrary, situated as it were on the threshold of the tropics, though but a few days’ sail from spain, shares in the charms which nature has lavished on the equinoctial regions. vegetation here displays some of her fairest and most majestic forms in the banana and the palm-tree. he who is alive to the charms of nature finds in this delicious island remedies still more potent than the climate. no abode appeared to me more fitted to dissipate melancholy, and restore peace to the perturbed mind, than that of teneriffe or madeira. these advantages are the effect not of the beauty of the site and the purity of the air alone: the moral feeling is no longer harrowed up by the sight of slavery, the presence of which is so revolting in the west indies, and in every other place to which european colonists have conveyed what they call their civilization and their industry.

in winter the climate of laguna is extremely foggy, and the inhabitants often complain of the cold. a fall of snow, however, has never been seen; a fact which may seem to indicate that the mean temperature of this town must be above 18.7° (15° r.), that is to say, higher than that of naples. i do not lay this down as an unexceptional conclusion, for in winter the refrigeration of the clouds does not depend so much on the mean temperature of the whole year, as on the instantaneous diminution of heat to which a district is exposed by its local situation. the mean temperature of the capital of mexico, for instance, is only 16.8° (13.5° r.), nevertheless, in the space of a hundred years snow has fallen only once, while in the south of europe and in africa it snows in places where the mean temperature is above 19°.

the vicinity of the sea renders the climate of laguna more mild in winter than might be expected, arising from its elevation above the level of the ocean. i was astonished to learn that m. broussonnet had planted in the midst of this town, in the garden of the marquis de nava, the bread-fruit tree (artocarpus incisa), and cinnamon-tree (laurus cinnamomum). these valuable productions of the south sea and the east indies are naturalized there as well as at orotava. does not this fact prove that the bread-fruit might flourish in calabria, sicily, and granada? the culture of the coffee-tree has not equally succeeded at laguna, though its fruit ripens at teguesta, as well as between the port of orotava and the village of st. juan de la rambla. it is probable that some local circumstances, perhaps the nature of the soil and the winds that prevail in the flowering season, are the cause of this phenomenon. in other regions, in the neighbourhood of naples, for instance, the coffee-tree thrives abundantly, though the mean temperature scarcely rises above 18 centigrade degrees.

no person has ascertained in the island of teneriffe, the lowest height at which snow falls every year. this fact, though easy of verification by barometrical measurements, has hitherto been generally neglected under every zone. it is nevertheless highly interesting both to agriculture in the colonies and meteorology, and fully as important as the measure of the limit of the perpetual snows. my observations furnished me with the data, set down in the following table:—

north latitude. lowest height at which snow falls. inferior limit of the perpetual snows. difference of the two preceding columns. mean temperature.

toises. metres. toises. metres. toises. metres. cent. reaum.

0 2040 3976 2460 4794 420 818 27 21.6.

20 1550 3020 2360 4598 810 1578 24.5 19.6.

40 0 0 1540 3001 1540 3001 17 13.6.

this table presents only the ordinary state of nature, that is to say, the phenomena as they are annually observed. exceptions founded on particular local circumstances, exist. thus it sometimes snows, though seldom, at naples, at lisbon, and even at malaga, consequently as low as the 37th degree of latitude: and, as we have just observed, snow has been seen to fall at mexico, the elevation of which is 1173 toises above the level of the ocean. this phenomenon, which had not been seen for several centuries, took place on the day that the jesuits were expelled, and was attributed by the people to that act of severity. a more striking exception was found in the climate of valladolid, the capital of the province of mechoacan. according to my measures, the height of this town, situate in latitude 19° 42′, is only a thousand toises: and yet, a few years before our arrival in new spain, the streets were covered with snow for some hours.

snow had been seen to fall also at teneriffe, in a place lying above esperanza de la laguna, very near the town of that name, in the gardens of which the artocarpus flourishes. this extraordinary fact was confirmed to m. broussonnet by very aged persons. the erica arborea, the myrica faya, and the arbutus callicarpa,* did not suffer from the snow; but it destroyed all the vines in the open air. this observation is interesting to vegetable physiology. in hot countries, the plants are so vigorous, that cold is less injurious to them, provided it be of short duration. i have seen the banana cultivated in the island of cuba, in places where the thermometer descends to seven centesimal degrees, and sometimes very near freezing point. in italy and spain the orange and date-trees do not perish, though the cold during the night may be two degrees below freezing point. in general it is remarked by cultivators, that the trees which grow in a fertile soil are less delicate, and consequently less affected by great changes in the temperature, than those which grow in land that affords but little nutriment.*

[* this fine arbutus, imported by m. broussonnet, is very different from the arbutus laurifolia, with which it has been confounded, but which belongs to north america.]

[* the mulberries, cultivated in the thin and sandy soils of countries bordering on the baltic sea, are examples of this feebleness of organization. the late frosts do more injury to them, than to the mulberries of piedmont. in italy a cold of 5° below freezing point does not destroy robust orange trees. according to m. galesio, these trees, less tender than the lemon and bergamot orange trees, freeze only at ten centesimal degrees below freezing point.]

in order to pass from the town of laguna to the port of orotava and the western coast of teneriffe, we cross at first a hilly region covered with black and argillaceous earth, in which are found some small crystals of pyroxene. the waters most probably detach these crystals from the neighbouring rocks, as at frascati, near rome. unfortunately, strata of ferruginous earth conceal the soil from the researches of the geologist. it is only in some ravines, that we find columnar basalts, somewhat curved, and above them very recent breccia, resembling volcanic tufa. the breccia contain fragments of the same basalts which they cover; and it is asserted that marine petrifactions are observed in them. the same phenomenon occurs in the vicentin, near montechio maggiore.

the valley of tacoronte is the entrance into that charming country, of which travellers of every nation have spoken with rapturous enthusiasm. under the torrid zone i found sites where nature is more majestic, and richer in the display of organic forms; but after having traversed the banks of the orinoco, the cordilleras of peru, and the most beautiful valleys of mexico, i own that i have never beheld a prospect more varied, more attractive, more harmonious in the distribution of the masses of verdure and of rocks, than the western coast of teneriffe.

the sea-coast is lined with date and cocoa trees. groups of the musa, as the country rises, form a pleasing contrast with the dragon-tree, the trunks of which have been justly compared to the tortuous form of the serpent. the declivities are covered with vines, which throw their branches over towering poles. orange trees loaded with flowers, myrtles, and cypress trees encircle the chapels reared to devotion on the isolated hills. the divisions of landed property are marked by hedges formed of the agave and the cactus. an innumerable quantity of cryptogamous plants, among which ferns are the most predominant, cover the walls, and are moistened by small springs of limpid water. in winter, when the volcano is buried under ice and snow, this district enjoys perpetual spring. in summer, as the day declines, the breezes from the sea diffuse a delicious freshness. the population of this coast is very considerable; and it appears to be still greater than it is, because the houses and gardens are distant from each other, which adds to the picturesque beauty of the scene. unhappily the real welfare of the inhabitants does not correspond with the exertions of their industry, or with the advantages which nature has lavished on this spot. the farmers are not land-owners; the fruits of their labour belong to the nobles; and those feudal institutions, which, for so long a time, spread misery throughout europe, still press heavily on the people of the canary islands.

from tegueste and tacoronte to the village of st. juan de la rambla (which is celebrated for its excellent malmsey wine), the rising hills are cultivated like a garden. i might compare them to the environs of capua and valentia, if the western part of teneriffe was not infinitely more beautiful on account of the proximity of the peak, which presents on every side a new point of view. the aspect of this mountain is interesting not merely from its gigantic mass; it excites the mind, by carrying it back to the mysterious source of its volcanic agency. for thousands of years, no flames or light have been perceived on the summit of the piton, nevertheless enormous lateral eruptions, the last of which took place in 1798, are proofs of the activity of a fire still far from being extinguished. there is also something that leaves a melancholy impression on beholding a crater in the centre of a fertile and well cultivated country. the history of the globe informs us, that volcanoes destroy what they have been a long series of ages in creating. islands, which the action of submarine fires has raised above the waters, are by degrees clothed in rich and smiling verdure; but these new lands are often laid waste by the renewed action of the same power which caused them to emerge from the bottom of the ocean. islets, which are now but heaps of scoriae and volcanic ashes, were once perhaps as fertile as the hills of tacoronte and sauzal. happy the country, where man has no distrust of the soil on which he lives!

pursuing our course to the port of orotava, we passed the smiling hamlets of matanza and victoria. these names are mingled together in all the spanish colonies, and they form an unpleasing contrast with the peaceful and tranquil feelings which those countries inspire. matanza signifies slaughter, or carnage; and the word alone recalls the price at which victory has been purchased. in the new world it generally indicates the defeat of the natives: at teneriffe, the village of matanza was built in a place* where the spaniards were conquered by those same guanches who soon after were sold as slaves in the markets of europe.

[* the ancient acantejo.]

before we reached orotava, we visited a botanic garden at a little distance from the port. we there found m. le gros, the french vice-consul, who had often scaled the summit of the peak, and who served us as an excellent guide. he was accompanying captain baudin in a voyage to the west indies, when a dreadful tempest, of which m. le dru has given an account in the narrative of his voyage to porto rico, forced the vessel to put into teneriffe. there m. le gros was led by the beauty of the spot to settle. it was he who augmented scientific knowledge by the first accurate ideas of the great lateral eruption of the peak, which has been very improperly called the explosion of the volcano of chahorra. this eruption took place on the 8th of june, 1798.

the establishment of a botanical garden at teneriffe is a very happy idea, on account of the influence it is likely to have on the progress of botany, and on the introduction of useful plants into europe. for the first conception of it we are indebted to the marquis de nava. he undertook, at an enormous expense, to level the hill of durasno, which rises as an amphitheatre, and which was begun to be planted in 1795. the marquis thought that the canary islands, from the mildness of their climate and geographical position, were the most suitable place for naturalising the productions of the east and west indies, and for inuring the plants gradually to the colder temperature of the south of europe. the plants of asia, africa, and south america, may easily be brought to orotava; and in order to introduce the bark-tree* into sicily, portugal, or grenada, it should be first planted at durasno, or at laguna, and the shoots of this tree may afterwards be transported into europe from the canaries. in happier times, when maritime wars shall no longer interrupt communication, the garden of teneriffe may become extremely useful with respect to the great number of plants which are sent from the indies to europe; for ere they reach our coasts, they often perish, owing to the length of the passage, during which they inhale an air impregnated with salt water. these plants would meet at orotava with the care and climate necessary for their preservation. at durasno, the protea, the psidium, the jambos, the chirimoya of peru,* the sensitive plant, and the heliconia, grow in the open air. we gathered the ripened seeds of several beautiful species of glycine from new holland, which the governor of cumana, mr. emparan, had successfully cultivated, and which grow wild on the coasts of south america.

[* i speak of the species of bark-tree (cinchona), which at peru, and in the kingdom of new granada, flourish on the back of the cordilleras, at the height of between 1000 and 1500 toises, in places where the thermometer is between nine and ten degrees during the day, and from three to four during the night. the orange bark-tree (cinchona lancifolia) is much less delicate than the red bark-tree (c. oblongifolia).]

[* annona cherimolia. lamarck.]

we arrived very late at the port of orotava,* if we may give the name of port to a road in which vessels are obliged to put to sea whenever the winds blow violently from the north-west. it is impossible to speak of orotava without recalling to the remembrance of the friends of science the name of don bernardo cologan, whose house at all times was open to travellers of every nation.

[* puerto de la cruz. the only fine port of the canary islands is that of st. sebastian, in the isle of gomara.]

we could have wished to have sojourned for some time in don bernardo’s house, and to have visited with him the charming scenery of st. juan de la rambla and of rialexo de abaxo.* but on a voyage such as we had undertaken, the present is but little enjoyed. continually haunted by the fear of not executing the designs of the morrow, we live in perpetual uneasiness. persons who are passionately fond of nature and the arts feel the same sensations, when they travel through switzerland and italy. enabled to see but a small portion of the objects which allure them, they are disturbed in their enjoyments by the restraints they impose on themselves at every step.

[* this last-named village stands at the foot of the lofty mountain of tygayga.]

on the morning of the 21st of june, we were on our way to the summit of the volcano. m. le gros, whose attentions were unwearied, m. lalande, secretary to the french consulate at santa cruz, and the english gardener at durasno, joined us on this excursion. the day was not very fine, and the summit of the peak, which is generally visible at orotava from sunrise till ten o’clock, was covered with thick clouds.

we were agreeably surprised by the contrast between the vegetation of this part of teneriffe, and that of the environs of santa cruz. under the influence of a cool and humid climate, the ground was covered with beautiful verdure; while on the road from santa cruz to laguna the plants exhibited nothing but capsules emptied of their seeds. near the port of santa cruz, the strength of the vegetation is an obstacle to geological research. we passed along the base of two small hills, which rise in the form of bells. observations made at vesuvius and in auvergne lead us to think that these hills owe their origin to lateral eruptions of the great volcano. the hill called montanita de la villa seems indeed to have emitted lavas; and according to the tradition of the guanches, an eruption took place in 1430. colonel franqui assured borda, that the place is still to be seen whence the melted matter issued; and that the ashes which covered the ground adjacent, were not yet fertilized. whenever the rock appeared, we discovered basaltic amygdaloid* covered with hardened clay,* which contains rapilli, or fragments of pumice-stone. this last formation resembles the tufas of pausilippo, and the strata of puzzolana, which i found in the valley of quito, at the foot of the volcano of pichincha. the amygdaloid has very long pores, like the superior strata of the lavas of vesuvius, arising probably from the action of an elastic fluid forcing its way through the matter in fusion. notwithstanding these analogies, i must here repeat, that in all the low region of the peak of teneriffe, on the side of orotava, i have met with no flow of lava, nor any current, the limits of which are strongly marked. torrents and inundations change the surface of the globe, and when a great number of currents of lava meet and spread over a plain, as i have seen at vesuvius, in the atrio dei cavalli, they seem to be confounded together, and wear the appearance of real strata.

[* basaltartiger mandelstein. werner.]

[* bimstein–conglomerat. w.]

the villa de orotava has a pleasant aspect at a distance, from the great abundance of water which runs through the principal streets. the spring of agua mansa, collected in two large reservoirs, turns several mills, and is afterward discharged among the vineyards of the adjacent hills. the climate is still more refreshing at the villa than at the port of la cruz, from the influence of the breeze, which blows strong after ten in the morning. the water, which has been dissolved in the air at a higher temperature, frequently precipitates itself; and renders the climate very foggy. the villa is nearly 160 toises (312 metres) above the level of the sea, consequently 200 toises lower than the site on which laguna is built: it is observed also, that the same kind of plants flower a month later in this latter place.

orotava, the ancient taoro of the guanches, is situated on a very steep declivity. the streets seem deserted; the houses are solidly built, and of a gloomy appearance. we passed along a lofty aqueduct, lined with a great number of fine ferns; and visited several gardens, in which the fruit trees of the north of europe are mingled with orange trees, pomegranate, and date trees. we were assured, that these last were as little productive here as on the coast of cumana. although we had been made acquainted, from the narratives of many travellers, with the dragon-tree of the garden of m. franqui, we were not the less struck with its enormous magnitude. we were told, that the trunk of this tree, which is mentioned in several very ancient documents as marking the boundaries of a field, was as gigantic in the fifteenth century as it is at the present time. its height appeared to us to be about 50 or 60 feet; its circumference near the roots is 45 feet. we could not measure higher, but sir george staunton found that, 10 feet from the ground, the diameter of the trunk is still 12 english feet; which corresponds perfectly with the statement of borda, who found its mean circumference 33 feet 8 inches, french measure. the trunk is divided into a great number of branches, which rise in the form of a candelabrum, and are terminated by tufts of leaves, like the yucca which adorns the valley of mexico. this division gives it a very different appearance from that of the palm-tree.

among organic creations, this tree is undoubtedly, together with the adansonia or baobab of senegal, one of the oldest inhabitants of our globe. the baobabs are of still greater dimensions than the dragon-tree of orotava. there are some which near the root measure 34 feet in diameter, though their total height is only from 50 to 60 feet. but we should observe, that the adansonia, like the ochroma, and all the plants of the family of bombax, grow much more rapidly* than the dracaena, the vegetation of which is very slow. that in m. franqui’s garden still bears every year both flowers and fruit. its aspect forcibly exemplifies “that eternal youth of nature,” which is an inexhaustible source of motion and of life.

[* it is the same with the plane-tree (platanus occidentalis) which m. michaux measured at marietta, on the banks of the ohio, and which, at twenty feet from the ground, was 15.7 feet in diameter. —“voyage a l’ouest des monts alleghany” 1804 page 93. the yew, chestnut, oak, plane-tree, deciduous cypress, bombax, mimosa, caesalpina, hymenaea, and dracaena, appear to me to be the plants which, in different climates, present specimens of the most extraordinary growth. an oak, discovered together with some gallic helmets in 1809, in the turf pits of the department of the somme, near the village of yseux, seven leagues from abbeville, was about the same size as the dragon-tree of orotava. according to a memoir by m. traullee, the trunk of this oak was 14 feet in diameter.]

the dracaena, which is seen only in cultivated spots in the canary islands, at madeira, and porto santo, presents a curious phenomenon with respect to the migration of plants. it has never been found in a wild state on the continent of africa. the east indies is its real country. how has this tree been transplanted to teneriffe, where it is by no means common? does its existence prove, that, at some very distant period, the guanches had connexions with other nations originally from asia?*

[* the form of the dragon-tree is exhibited in several species of the genus dracaena, at the cape of good hope, in china, and in new zealand. but in new zealand it is superseded by the form of the yucca; for the dracaena borealis of aiton is a convallaria, of which it has all the appearance. the astringent juice, known in commerce by the name of dragon’s blood, is, according to the inquiries we made on the spot, the produce of several american plants, which do not belong to the same genus and of which some are lianas. at laguna, toothpicks steeped in the juice of the dragon-tree are made in the nunneries, and are much extolled as highly useful for keeping the gums in a healthy state.]

on leaving orotava, a narrow and stony pathway led us through a beautiful forest of chestnut trees (el monte de castanos), to a site covered with brambles, some species of laurels, and arborescent heaths. the trunks of the latter grow to an extraordinary size; and the flowers with which they are loaded form an agreeable contrast, during a great part of the year, to the hypericum canariense, which is very abundant at this height. we stopped to take in our provision of water under a solitary fir-tree. this station is known in the country by the name of pino del dornajito. its height, according to the barometrical measurement of m. de borda, is 522 toises; and it commands a magnificent prospect of the sea, and the whole of the northern part of the island. near pino del dornajito, a little on the right of the pathway, is a copious spring of water, into which we plunged the thermometer, which fell to 15.4°. at a hundred toises distance from this spring is another equally limpid. if we admit that these waters indicate nearly the mean heat of the place whence they issue, we may fix the absolute elevation of the station at 520 toises, supposing the mean temperature of the coast to be 21°, and allowing one degree for the decrement of caloric corresponding under this zone to 93 toises. we should not be surprised if this spring remained a little below the heat of the air, since it probably takes its source in some more elevated part of the peak, and possibly communicates with the small subterranean glaciers of which we shall speak hereafter. the accordance just observed between the barometrical and thermometrical measures is so much more striking, because in mountainous countries, with steep declivities, the springs generally indicate too great a decrement of caloric, for they unite small currents of water, which filtrate at different heights, and their temperature is consequently the mean between the temperature of these currents. the spring of dornajito has considerable reputation in the country; and at the time i was there, it was the only one known on the road which leads to the summit of the volcano. the formation of springs demands a certain regularity in the direction and inclination of the strata. on a volcanic soil, porous and splintered rocks absorb the rain waters, and convey them to considerable depths. hence arises that aridity observed in the greater part of the canary islands, notwithstanding the considerable height of their mountains, and the mass of clouds which navigators behold incessantly overhanging this archipelago.

from pino del dornajito to the crater of the volcano we continued to ascend without crossing a single valley; for the small ravines (barancos) do not merit this name. to the eye of the geologist the whole island of teneriffe is but one mountain, the almost elliptical base of which is prolonged to the north-east, and in which may be distinguished several systems of volcanic rocks formed at different epochs. the chahorra, or montana colorada, and the urca, considered in the country as insulated volcanoes, are only little hills abutting on the peak, and masking its pyramidal form. the great volcano, the lateral eruptions of which have given birth to vast promontories, is not however precisely in the centre of the island, and this peculiarity of structure appears the less surprising, if we recollect that, as the learned mineralogist m. cordier has observed, it is not perhaps the small crater of the piton which has been the principal agent in the changes undergone by the island of teneriffe.

above the region of arborescent heaths, called monte verde, is the region of ferns. nowhere, in the temperate zone, have i seen such an abundance of the pteris, blechnum, and asplenium; yet none of these plants have the stateliness of the arborescent ferns which, at the height of five or six hundred toises, form the principal ornament of equinoctial america. the root of the pteris aquilina serves the inhabitants of palma and gomera for food; they grind it to powder, and mix with it a quantity of barley-meal. this composition, when boiled, is called gofio; the use of so homely an aliment is a proof of the extreme poverty of the lower order of people in the canary islands.

monte verde is intersected by several small and very arid ravines (canadas), and the region of ferns is succeeded by a wood of juniper trees and firs, which has suffered greatly from the violence of hurricanes. in this place, mentioned by some travellers under the name of caravela,* mr. eden states that in the year 1705 he saw little flames, which, according to the doctrine of the naturalists of his time, he attributes to sulphurous exhalations igniting spontaneously. we continued to ascend, till we came to the rock of la gayta and to portillo: traversing this narrow pass between two basaltic hills, we entered the great plain of spartium. at the time of the voyage of laperouse, m. manneron had taken the levels of the peak, from the port of orotava to this elevated plain, near 1400 toises above the level of the sea; but the want of water, and the misconduct of the guides, prevented him from taking the levels to the top of the volcano. the results of the operation, (which was two-thirds completed,) unfortunately were not sent to europe, and the work is still to be recommenced from the sea-coast.

[* “philosophical transactions” volume 29 page 317. carabela is the name of a vessel with lateen sails. the pines of the peak formerly were used as masts of vessels.]

we spent two hours and a half in crossing the llano del retama, which appears like an immense sea of sand. notwithstanding the elevation of this site, the centigrade thermometer rose in the shade toward sunset, to 13.8°, or 3.7° higher than toward noon at monte verde. this augmentation of heat could be attributed only to the reverberation from the ground, and the extent of the plain. we suffered much from the suffocating dust of the pumice-stone, in which we were continually enveloped. in the midst of this plain are tufts of the retama, which is the spartium nubigenum of aiton. m. de martiniere, one of the botanists who perished in the expedition of laperouse, wished to introduce this beautiful shrub into languedoc, where firewood is very scarce. it grows to the height of nine feet, and is loaded with odoriferous flowers, with which the goat hunters, that we met in our road, had decorated their hats. the goats of the peak, which are of a deep brown colour, are reckoned delicious food; they browse on the spartium, and have run wild in the deserts from time immemorial. they have been transported to madeira, where they are preferred to the goats of europe.

as far as the rock of gayta, or the entrance of the extensive llano del retama, the peak of teneriffe is covered with beautiful vegetation. there are no traces of recent devastation. we might have imagined ourselves scaling the side of some volcano, the fire of which had been extinguished as remotely as that of monte cavo, near rome; but scarcely had we reached the plain covered with pumice-stone, when the landscape changed its aspect, and at every step we met with large blocks of obsidian thrown out by the volcano. everything here speaks perfect solitude. a few goats and rabbits only bound across the plain. the barren region of the peak is nine square leagues; and as the lower regions viewed from this point retrograde in the distance, the island appears an immense heap of torrefied matter, hemmed round by a scanty border of vegetation.

from the region of the spartium nubigenum we passed through narrow defiles, and small ravines hollowed at a very remote time by the torrents, first arriving at a more elevated plain (el monton de trigo), then at the place where we intended to pass the night. this station, which is more than 1530 toises above the coast, bears the name of the english halt (estancia de los ingleses*), no doubt because most of the travellers, who formerly visited the peak, were englishmen. two inclined rocks form a kind of cavern, which affords a shelter from the winds. this point, which is higher than the summit of the canigou, can be reached on the backs of mules; and here has ended the expedition of numbers of travellers, who on leaving orotava hoped to have ascended to the brink of the crater. though in the midst of summer, and under an african sky, we suffered from cold during the night. the thermometer descended as low as to five degrees. our guides made a large fire with the dry branches of retama. having neither tents nor cloaks, we lay down on some masses of rock, and were singularly incommoded by the flame and smoke, which the wind drove towards us. we had attempted to form a kind of screen with cloths tied together, but our enclosure took fire, which we did not perceive till the greater part had been consumed by the flames. we had never passed a night on a point so elevated, and we then little imagined that we should, one day, on the ridge of the cordilleras, inhabit towns higher than the summit of the volcano we were to scale on the morrow. as the temperature diminished, the peak became covered with thick clouds. the approach of night interrupts the play of the ascending current, which, during the day, rises from the plains towards the high regions of the atmosphere; and the air, in cooling, loses its capacity of suspending water. a strong northerly wind chased the clouds; the moon at intervals, shooting through the vapours, exposed its disk on a firmament of the darkest blue; and the view of the volcano threw a majestic character over the nocturnal scenery. sometimes the peak was entirely hidden from our eyes by the fog, at other times it broke upon us in terrific proximity; and, like an enormous pyramid, threw its shadow over the clouds rolling beneath our feet.

[* this denomination was in use as early as the beginning of the last century. mr. eden, who corrupts all spanish words, as do most travellers in our own times, calls it the stancha: it is the station des rochers of m. borda, as is proved by the barometrical heights there observed. these heights were in 1803, according to m. cordier, 19 inches 9.5 lines; and in 1776, according to messrs. borda and varela, 19 inches 9.8 lines; the barometer at orotava keeping within nearly a line at the same height.]

about three in the morning, by the sombrous light of a few fir torches, we started on our journey to the summit of the piton. we scaled the volcano on the north-east side, where the declivities are extremely steep; and after two hours’ toil, we reached a small plain, which, on account of its elevated position, bears the name of alta vista. this is the station of the neveros, those natives, whose occupation it is to collect ice and snow, which they sell in the neighbouring towns. their mules, better practised in climbing mountains than those hired by travellers, reach alta vista, and the neveros are obliged to transport the snow to that place on their backs. above this point commences the malpays, a term by which is designated here, as well as in mexico, peru, and every other country subject to volcanoes, a ground destitute of vegetable mould, and covered with fragments of lava.

we turned to the right to examine the cavern of ice, which is at the elevation of 1728 toises, consequently below the limit of the perpetual snows in this zone. probably the cold which prevails in this cavern, is owing to the same causes which perpetuate the ice in the crevices of mount jura and the apennines, and on which the opinions of naturalists are still much divided. this natural ice-house of the peak has, nevertheless, none of those perpendicular openings, which give emission to the warm air, while the cold air remains undisturbed at the bottom. it would seem that the ice is preserved in it on account of its mass, and because its melting is retarded by the cold, which is the consequence of quick evaporation. this small subterraneous glacier is situated in a region, the mean temperature of which is probably not under three degrees; and it is not, like the true glaciers of the alps, fed by the snow waters that flow from the summits of the mountains. during winter the cavern is filled with ice and snow; and as the rays of the sun do not penetrate beyond the mouth, the heats of summer are not sufficient to empty the reservoir. the existence of a natural ice-house depends, consequently, rather on the quantity of snow which enters it in winter, and the small influence of the warm winds in summer, than on the absolute elevation of the cavity, and the mean temperature of the layer of air in which it is situated. the air contained in the interior of a mountain is not easily displaced, as is exemplified by monte testaccio at rome, the temperature of which is so different from that of the surrounding atmosphere. on chimborazo enormous heaps of ice are found covered with sand, and, in the same manner as at the peak, far below the inferior limit of the perpetual snows.

it was near the ice–cavern (cueva del hielo), that, in the voyage of laperouse, messrs. lamanon and monges made their experiments on the temperature of boiling water. these naturalists found it 88.7°, the barometer at nineteen inches one line. in the kingdom of new grenada, at the chapel of guadaloupe, near santa–fe de bogota, i have seen water boil at 89.9°, under a pressure of 19 inches 1.9 lines, at tambores, in the province of popayan, senor caldas found the heat of boiling water 89.5°, the barometer being at 18 inches 11.6 lines. these results might lead us to suspect, that, in the experiment of m. lamanon, the water had not reached the maximum of its temperature.

day was beginning to dawn when we left the ice-cavern. we observed, during the twilight, a phenomenon which is not unusual on high mountains, but which the position of the volcano we were scaling rendered very striking. a layer of white and fleecy clouds concealed from us the sight of the ocean, and the lower region of the island. this layer did not appear above 800 toises high; the clouds were so uniformly spread, and kept so perfect a level, that they wore the appearance of a vast plain covered with snow. the colossal pyramid of the peak, the volcanic summits of lancerota, of forteventura, and the isle of palma, were like rocks amidst this vast sea of vapours, and their black tints were in fine contrast with the whiteness of the clouds.

while we were climbing over the broken lavas of the malpays, we perceived a very curious optical phenomenon, which lasted eight minutes. we thought we saw on the east side small rockets thrown into the air. luminous points, about seven or eight degrees above the horizon, appeared first to move in a vertical direction; but their motion was gradually changed into a horizontal oscillation. our fellow-travellers, our guides even, were astonished at this phenomenon, without our having made any remark on it to them. we thought, at first sight, that these luminous points, which floated in the air, indicated some new eruption of the great volcano of lancerota; for we recollected that bouguer and la condamine, in scaling the volcano of pichincha, were witnesses of the eruption of cotopaxi. but the illusion soon ceased, and we found that the luminous points were the images of several stars magnified by the vapours. these images remained motionless at intervals, they then seemed to rise perpendicularly, descended sideways, and returned to the point whence they had departed. this motion lasted one or two seconds. though we had no exact means of measuring the extent of the lateral shifting, we did not the less distinctly observe the path of the luminous point. it did not appear double from an effect of mirage, and left no trace of light behind. bringing, with the telescope of a small sextant by troughton, the stars into contact with the lofty summit of a mountain in lancerota, i observed that the oscillation was constantly directed towards the same point, that is to say, towards that part of the horizon where the disk of the sun was to appear; and that, making allowance for the motion of the star in its declination, the image returned always to the same place. these appearances of lateral refraction ceased long before daylight rendered the stars quite invisible. i have faithfully related what we saw during the twilight, without undertaking to explain this extraordinary phenomenon, of which i published an account in baron zach’s astronomical journal, twelve years ago. the motion of the vesicular vapours, caused by the rising of the sun; the mingling of several layers of air, the temperature and density of which were very different, no doubt contributed to produce an apparent movement of the stars in the horizontal direction. we see something similar in the strong undulations of the solar disk, when it cuts the horizon; but these undulations seldom exceed twenty seconds, while the lateral motion of the stars, observed at the peak, at more than 1800 toises, was easily distinguished by the naked eye, and seemed to exceed all that we have thought it possible to consider hitherto as the effect of the refraction of the light of the stars. on the top of the andes, at antisana, i observed the sun-rise, and passed the whole night at the height of 2100 toises, without noting any appearance resembling this phenomenon.

i was anxious to make an exact observation of the instant of sun-rising at an elevation so considerable as that we had reached on the peak of teneriffe. no traveller, furnished with instruments, had as yet taken such an observation. i had a telescope and a chronometer, which i knew to be exceedingly correct. in the part where the sun was to appear the horizon was free from vapour. we perceived the upper limb at 4 hours 48 minutes 55 seconds apparent time, and what is very remarkable, the first luminous point of the disk appeared immediately in contact with the limit of the horizon, consequently we saw the true horizon; that is to say, a part of the sea farther distant than 43 leagues. it is proved by calculation that, under the same parallel in the plain, the rising would have begun at 5 hours 1 minute 50.4 seconds, or 11 minutes 51.3 seconds later than at the height of the peak. the difference observed was 12 minutes 55 seconds, which arose no doubt from the uncertainty of the refraction for a zenith distance, of which observations are wanting.

we were surprised at the extreme slowness with which the lower limb of the sun seemed to detach itself from the horizon. this limb was not visible till 4 hours 56 minutes 56 seconds. the disc of the sun, much flattened, was well defined; during the ascent there was neither double image nor lengthening of the lower limb. the duration of the sun’s rising being triple that which we might have expected in this latitude, we must suppose that a fog-bank, very uniformly extended, concealed the true horizon, and followed the sun in its ascent. notwithstanding the libration of the stars,* which we had observed towards the east, we could not attribute the slowness of the rising to an extraordinary refraction of the rays occasioned by the horizon of the sea; for it is precisely at the rising of the sun, as le gentil daily observed at pondicherry, and as i have several times remarked at cumana, that the horizon sinks, on account of the elevation of temperature in the stratum of the air which lies immediately over the surface of the ocean.

[* a celebrated astronomer, baron zach, has compared this phenomenon of an apparent libration of the stars to that described in the georgics (lib. 50 v. 365). but this passage relates only to the falling stars, which the ancients, (like the mariners of modern times) considered as a prognostic of wind.]

the road, which we were obliged to clear for ourselves across the malpays, was extremely fatiguing. the ascent is steep, and the blocks of lava rolled from beneath our feet. i can compare this part of the road only to the moraine of the alps or that mass of pebbly stones which we find at the lower extremity of the glaciers. at the peak the lava, broken into sharp pieces, leaves hollows, in which we risked falling up to our waists. unfortunately the listlessness of our guides contributed to increase the difficulty of this ascent. unlike the guides of the valley of chamouni, or the nimble-footed guanches, who could, it is asserted, seize the rabbit or wild goat in its course, our canarian guides were models of the phlegmatic. they had wished to persuade us on the preceding evening not to go beyond the station of the rocks. every ten minutes they sat down to rest themselves, and when unobserved they threw away the specimens of obsidian and pumice-stone, which we had carefully collected. we discovered at length that none of them had ever visited the summit of the volcano.

after three hours’ walking, we reached, at the extremity of the malpays, a small plain, called la rambleta, from the centre of which the piton, or sugar-loaf, takes its rise. on the side toward orotava the mountain resembles those pyramids with steps that are seen at fayoum and in mexico; for the elevated plains of retama and rambleta form two tiers, the first of which is four times higher than the second. if we suppose the total height of the peak to be 1904 toises, the rambleta is 1820 toises above the level of the sea. here are found those spiracles, which are called by the natives the nostrils of the peak (narices del pico). watery and heated vapours issue at intervals from several crevices in the ground, and the thermometer rose to 43.2°. m. labillardiere had found the temperature of these vapours, eight years before us, 53.7°; a difference which does not perhaps prove so much a diminution of activity in the volcano, as a local change in the heating of its internal surface. the vapours have no smell, and seem to be pure water. a short time before the great eruption of mount vesuvius, in 1805, m. gay–lussac and myself had observed that water, under the form of vapour, in the interior of the crater, did not redden paper which had been dipped in syrup of violets. i cannot, however, admit the bold hypothesis, according to which the nostrils of the peak are to be considered as the vents of an immense apparatus of distillation, the lower part of which is situated below the level of the sea. since the time when volcanoes have been carefully studied, and the love of the marvellous has been less apparent in works on geology, well founded doubts have been raised respecting these direct and constant communications between the waters of the sea and the focus of the volcanic fire.* we may find a very simple explanation of a phenomenon, that has in it nothing very surprising. the peak is covered with snow during part of the year; we ourselves found it still so in the plain of rambleta. messrs. o’donnel and armstrong discovered in 1806 a very abundant spring in the malpays, a hundred toises above the cavern of ice, which is perhaps fed partly by this snow. everything consequently leads us to presume that the peak of teneriffe, like the volcanoes of the andes, and those of the island of manilla, contains within itself great cavities, which are filled with atmospherical water, owing merely to filtration. the aqueous vapours exhaled by the narices and crevices of the crater, are only those same waters heated by the interior surfaces down which they flow.

[* this question has been examined with much sagacity by m. brieslak, in his “introduzzione alla geologia,” tome 2 pages 302, 323, 347. cotopaxi and popocatepetl, which i saw ejecting smoke and ashes, in 1804, are farther from both the pacific and the gulf of the antilles, than grenoble is from the mediterranean, and orleans from the atlantic. we must not consider the fact as merely accidental, that we have not yet discovered an active volcano more than 40 leagues distant from the ocean; but i consider the hypothesis, that the waters of the sea are absorbed, distilled, and decomposed by volcanoes, as very doubtful.]

we had yet to scale the steepest part of the mountain, the piton, which forms the summit. the slope of this small cone, covered with volcanic ashes, and fragments of pumice-stone, is so steep, that it would have been almost impossible to reach the top, had we not ascended by an old current of lava, the debris of which have resisted the ravages of time. these debris form a wall of scorious rock, which stretches into the midst of the loose ashes. we ascended the piton by grasping these half-decomposed scoriae, which often broke in our hands. we employed nearly half an hour to scale a hill, the perpendicular height of which is scarcely ninety toises. vesuvius, three times lower than the peak of teneriffe, is terminated by a cone of ashes almost three times higher, but with a more accessible and easy slope. of all the volcanoes which i have visited, that of jorullo, in mexico, is the only one that is more difficult to climb than the peak, because the whole mountain is covered with loose ashes.

when the sugar-loaf (el piton) is covered with snow, as it is in the beginning of winter, the steepness of its declivity may be very dangerous to the traveller. m. le gros showed us the place where captain baudin was nearly killed when he visited the peak of teneriffe. that officer had the courage to undertake, in company with the naturalists advenier, mauger, and riedle, an excursion to the top of the volcano about the end of december, 1797. having reached half the height of the cone, he fell, and rolled down as far as the small plain of rambleta; happily a heap of lava, covered with snow, hindered him from rolling farther with accelerated velocity. i have been told, that in switzerland a traveller was suffocated by rolling down the declivity of the col de balme, over the compact turf of the alps.

when we gained the summit of the piton, we were surprised to find scarcely room enough to seat ourselves conveniently. we were stopped by a small circular wall of porphyritic lava, with a base of pitchstone, which concealed from us the view of the crater.* the west wind blew with such violence that we could scarcely stand. it was eight in the morning, and we suffered severely from the cold, though the thermometer kept a little above freezing point. for a long time we had been accustomed to a very high temperature, and the dry wind increased the feeling of cold, because it carried off every moment the small atmosphere of warm and humid air, which was formed around us from the effect of cutaneous perspiration.

[* called la caldera, or the caldron of the peak, a denomination which recalls to mind the oules of the pyrenees.]

the brink of the crater of the peak bears no resemblance to those of most of the other volcanoes which i have visited: for instance, the craters of vesuvius, jorullo, and pichincha. in these the piton preserves its conic figure to the very summit: the whole of their declivity is inclined the same number of degrees, and uniformly covered with a layer of pumice-stone very minutely divided; when we reach the top of these volcanoes, nothing obstructs the view of the bottom of the crater. the peaks of teneriffe and cotopaxi, on the contrary, are of very different construction. at their summit a circular wall surrounds the crater; which wall, at a distance, has the appearance of a small cylinder placed on a truncated cone. on cotopaxi this peculiar construction is visible to the naked eye at more than 2000 toises distance; and no person has ever reached the crater of that volcano. on the peak of teneriffe, the wall, which surrounds the crater like a parapet, is so high, that it would be impossible to reach the caldera, if, on the eastern side, there was not a breach, which seems to have been the effect of a flowing of very old lava. we descended through this breach toward the bottom of the funnel, the figure of which is elliptic. its greater axis has a direction from north-west to south-east, nearly north 35° west. the greatest breadth of the mouth appeared to us to be 300 feet, the smallest 200 feet, which numbers agree very nearly with the measurement of mm. verguin, varela, and borda.

it is easy to conceive, that the size of a crater does not depend solely on the height and mass of the mountain, of which it forms the principal air-vent. this opening is indeed seldom in direct ratio with the intensity of the volcanic fire, or with the activity of the volcano. at vesuvius, which is but a hill compared with the peak of teneriffe, the diameter of the crater is five times greater. when we reflect, that very lofty volcanoes throw out less matter from their summits than from lateral openings, we should be led to think, that the lower the volcanoes, their force and activity being the same, the more considerable ought to be their craters. in fact, there are immense volcanoes in the andes, which have but very small openings; and we might establish as a geological principle, that the most colossal mountains have craters of little extent at the summits, if the cordilleras did not present many instances to the contrary.* i shall have occasion, in the progress of this work, to cite a number of facts, which will throw some light on what may be called the external structure of volcanoes. this structure is as varied as the volcanic phenomena themselves; and in order to raise ourselves to geological conceptions worthy of the greatness of nature, we must set aside the idea that all volcanoes are formed after the model of vesuvius, stromboli, and etna.

[* the great volcanoes of cotopaxi and rucupichincha have craters, the diameters of which, according to my measurements, exceed 400 and 700 toises.]

the external edges of the caldera are almost perpendicular. their appearance is somewhat like the somma, seen from the atrio dei cavalli. we descended to the bottom of the crater on a train of broken lava, from the eastern breach of the enclosure. the heat was perceptible only in a few crevices, which gave vent to aqueous vapours with a peculiar buzzing noise. some of these funnels or crevices are on the outside of the enclosure, on the external brink of the parapet that surrounds the crater. we plunged the thermometer into them, and saw it rise rapidly to 68 and 75°. it no doubt indicated a higher temperature, but we could not observe the instrument till we had drawn it up, lest we should burn our hands. m. cordier found several crevices, the heat of which was that of boiling water. it might be thought that these vapours, which are emitted in gusts, contain muriatic or sulphurous acid; but when condensed, they have no particular taste; and experiments, which have been made with re-agents, prove that the chimneys of the peak exhale only pure water. this phenomenon, analogous to that which i observed in the crater of jorullo, deserves the more attention, as muriatic acid abounds in the greater part of volcanoes, and as m. vauquelin has discovered it even in the porphyritic lavas of sarcouy in auvergne.

i sketched on the spot a view of the interior edge of the crater, as it presented itself in the descent by the eastern break. nothing is more striking than the manner in which these strata of lava are piled on one another, exhibiting the sinuosities of the calcareous rock of the higher alps. these enormous ledges, sometimes horizontal, sometimes inclined and undulating, are indicative of the ancient fluidity of the whole mass, and of the combination of several deranging causes, which have determined the direction of each flow. the top of the circular wall exhibits those curious ramifications which we find in coke. the northern edge is most elevated. towards the south-west the enclosure is considerably sunk and an enormous mass of scorious lava seems glued to the extremity of the brink. on the west the rock is perforated; and a large opening gives a view of the horizon of the sea. the force of the elastic vapours perhaps formed this natural aperture, at the time of some inundation of lava thrown out from the crater.

the inside of this funnel indicates a volcano, which for thousands of years has vomited no fire but from its sides. this conclusion is not founded on the absence of great openings, which might be expected in the bottom of the caldera. those whose experience is founded on personal observation, know that several volcanoes, in the intervals of an eruption, appear filled up, and almost extinguished; but that in these same mountains, the crater of the volcano exhibits layers of scoriae, rough, sonorous, and shining. we observe hillocks and intumescences caused by the action of the elastic vapours, cones of broken scoriae and ashes which cover the funnels. none of these phenomena characterise the crater of the peak of teneriffe; its bottom is not in the state which ensues at the close of an eruption. from the lapse of time, and the action of the vapours, the inside walls are detached, and have covered the basin with great blocks of lithoid lavas.

the bottom of the caldera is reached without danger. in a volcano, the activity of which is principally directed towards the summit, such as vesuvius, the depth of the crater varies before and after each eruption; but at the peak of teneriffe the depth appears to have remained unchanged for a long time. eden, in 1715, estimated it at 115 feet; cordier, in 1803, at 110 feet. judging by mere inspection, i should have thought the funnel of still less depth. its present state is that of a solfatara; and it is rather an object of curious investigation, than of imposing aspect. the majesty of the site consists in its elevation above the level of the sea, in the profound solitude of these lofty regions, and in the immense space over which the eye ranges from the summit of the mountain.

the wall of compact lava, forming the enclosure of the caldera, is snow-white at its surface. the same colour prevails in the inside of the solfatara of puzzuoli. when we break these lavas, which might be taken at some distance for calcareous stone, we find in them a blackish brown nucleus. porphyry, with basis of pitch-stone, is whitened externally by the slow action of the vapours of sulphurous acid gas. these vapours rise in abundance; and what is rather remarkable, through crevices which seem to have no communication with the apertures that emit aqueous vapours. we may be convinced of the presence of the sulphurous acid, by examining the fine crystals of sulphur, which are everywhere found in the crevices of the lava. this acid, combined with the water with which the soil is impregnated, is transformed into sulphuric acid by contact with the oxygen of the atmosphere. in general, the humidity in the crater of the peak is more to be feared than the heat; and they who seat themselves for a while on the ground find their clothes corroded. the porphyritic lavas are affected by the action of the sulphuric acid: the alumine, magnesia, soda, and metallic oxides gradually disappear; and often nothing remains but the silex, which unites in mammillary plates, like opal. these siliceous concretions,* which m. cordier first made known, are similar to those found in the isle of ischia, in the extinguished volcanoes of santa fiora, and in the solfatara of puzzuoli. it is not easy to form an idea of the origin of these incrustations. the aqueous vapours, discharged through great spiracles, do not contain alkali in solution, like the waters of the geyser, in iceland. perhaps the soda contained in the lavas of the peak acts an important part in the formation of these deposits of silex. there may exist in the crater small crevices, the vapours of which are not of the same nature as those on which travellers, whose attention has been directed simultaneously to a great number of objects, have made experiments.

[* opalartiger kieselsinter. the siliceous gurh of the volcanoes of the isle of france contains, according to klaproth, 0.72 silex, and 0.21 water; and thus comes near to opal, which karsten considers as a hydrated silex.]

seated on the northern brink of the crater, i dug a hole of some inches in depth; and the thermometer placed in this hole rose rapidly to 42°. hence we may conclude what must be the heat in this solfatara at the depth of thirty or forty fathoms. the sulphur reduced into vapour is condensed into fine crystals, which however are not equal in size to those m. dolomieu brought from sicily. they are semi-diaphanous octahedrons, very brilliant on the surface, and of a conchoidal fracture. these masses, which will one day perhaps be objects of commerce, are constantly bedewed with sulphurous acid. i had the imprudence to wrap up a few, in order to preserve them, but i soon discovered that the acid had consumed not only the paper which contained them, but a part also of my mineralogical journal. the heat of the vapours, which issue from the crevices of the caldera, is not sufficiently great to combine the sulphur while in a state of minute division, with the oxygen of the atmospheric air; and after the experiment i have just cited on the temperature of the soil, we may presume that the sulphurous acid is formed at a certain depth,* in cavities to which the external air has free access.

[* an observer, in general very accurate, m. breislack, asserts that the muriatic acid always predominates in the vapours of vesuvius. this assertion is contrary to what m. gay–lussac and myself observed, before the great eruption of 1805, and while the lava was issuing from the crater. the smell of the sulphurous acid, so easy to distinguish, was perceptible at a great distance; and when the volcano threw out scoriae, the smell was mingled with that of petroleum.]

the vapours of heated water, which act on the fragments of lava scattered about on the caldera, reduce certain parts of it to a state of paste. on examining, after i had reached america, those earthy and friable masses, i found crystals of sulphate of alumine. mm. davy and gay–lussac have already made the ingenious remark, that two bodies highly inflammable, the metals of soda and potash, have probably an important part in the action of a volcano; now the potash necessary to the formation of alum is found not only in feldspar, mica, pumice-stone, and augite, but also in obsidian. this last substance is very common at teneriffe, where it forms the basis of the tephrinic lava. these analogies between the peak of teneriffe and the solfatara of puzzuoli, might no doubt be shown to be more numerous, if the former were more accessible, and had been frequently visited by naturalists.

an expedition to the summit of the volcano of teneriffe is interesting, not solely on account of the great number of phenomena which are the objects of scientific research; it has still greater attractions from the picturesque beauties which it lays open to those who are feelingly alive to the majesty of nature. it is a difficult task to describe the sensations, which are the more forcible, inasmuch as they have something undefined, produced by the immensity of the space as well as by the vastness, the novelty, and the multitude of the objects, amidst which we find ourselves transported. when a traveller attempts to describe the loftiest summits of the globe, the cataracts of the great rivers, the tortuous valleys of the andes, he incurs the danger of fatiguing his readers by the monotonous expression of his admiration. it appears to me more conformable to the plan i have proposed to myself in this narrative, to indicate the peculiar character that distinguishes each zone: we exhibit with more clearness the physiognomy of the landscape, in proportion as we endeavour to sketch its individual features, to compare them with each other, and to discover by this kind of analysis the sources of the enjoyments, furnished by the great picture of nature.

travellers have learned by experience, that views from the summits of very lofty mountains are neither so beautiful, picturesque, nor so varied, as those from heights which do not exceed that of vesuvius, righi, and the puy-dedome. colossal mountains, such as chimborazo, antisana, or mount rosa, compose so large a mass, that the plains covered with rich vegetation are seen only in the immensity of distance, and a blue and vapoury tint is uniformly spread over the landscape. the peak of teneriffe, from its slender form and local position, unites the advantages of less lofty summits with those peculiar to very great heights. we not only discern from its top a vast expanse of sea, but we perceive also the forests of teneriffe, and the inhabited parts of the coasts, in a proximity calculated to produce the most beautiful contrasts of form and colour. we might say, that the volcano overwhelms with its mass the little island which serves as its base, and it shoots up from the bosom of the waters to a height three times loftier than the region where the clouds float in summer. if its crater, half extinguished for ages past, shot forth flakes of fire like that of stromboli in the aeolian islands, the peak of teneriffe, like a lighthouse, would serve to guide the mariner in a circuit of more than 260 leagues.

when we were seated on the external edge of the crater, we turned our eyes towards the north-west, where the coasts are studded with villages and hamlets. at our feet, masses of vapour, constantly drifted by the winds, afforded us the most variable spectacle. a uniform stratum of clouds, similar to that already described, and which separated us from the lower regions of the island, had been pierced in several places by the effect of the small currents of air, which the earth, heated by the sun, began to send towards us. the port of orotava, its vessels at anchor, the gardens and the vineyards encircling the town, shewed themselves through an opening which seemed to enlarge every instant. from the summit of these solitary regions our eyes wandered over an inhabited world; we enjoyed the striking contrast between the bare sides of the peak, its steep declivities covered with scoriae, its elevated plains destitute of vegetation, and the smiling aspect of the cultured country beneath. we beheld the plants divided by zones, as the temperature of the atmosphere diminished with the elevation of the site. below the piton, lichens begin to cover the scorious and lustrous lava: a violet,* akin to the viola decumbens, rises on the slope of the volcano at 1740 toises of height; it takes the lead not only of the other herbaceous plants, but even of the gramina, which, in the alps and on the ridge of the cordilleras, form close neighbourhood with the plants of the family of the cryptogamia. tufts of retama, loaded with flowers, adorn the valleys hollowed out by the torrents, and encumbered with the effects of the lateral eruptions. below the retama, lies the region of ferns, bordered by the tract of the arborescent heaths. forests of laurel, rhamnus, and arbutus, divide the ericas from the rising grounds planted with vines and fruit trees. a rich carpet of verdure extends from the plain of spartium, and the zone of the alpine plants even to the groups of the date tree and the musa, at the feet of which the ocean appears to roll. i here pass slightly over the principal features of this botanical chart, as i shall enter hereafter into some farther details respecting the geography of the plants of the island of teneriffe.*

[* viola cheiranthifolia.]

[* see below.]

the seeming proximity, in which, from the summit of the peak, we behold the hamlets, the vineyards, and the gardens on the coast, is increased by the prodigious transparency of the atmosphere. notwithstanding the great distance, we could distinguish not only the houses, the sails of the vessels, and the trunks of the trees, but we could discern the vivid colouring of the vegetation of the plains. these phenomena are owing not only to the height of the site, but to the peculiar modifications of the air in warm climates. in every zone, an object placed on a level with the sea, and viewed in a horizontal direction, appears less luminous, than when seen from the top of a mountain, where vapours arrive after passing through strata of air of decreasing density. differences equally striking are produced by the influence of climate. the surface of a lake or large river is less resplendent, when we see it at an equal distance, from the top of the higher alps of switzerland, than when we view it from the summit of the cordilleras of peru or of mexico. in proportion as the air is pure and serene, the solution of the vapours becomes more complete, and the light loses less in its passage. when from the shores of the pacific we ascend the elevated plain of quito, or that of antisana, we are struck for some days by the nearness at which we imagine we see objects which are actually seven or eight leagues distant. the peak of teyde has not the advantage of being situated in the equinoctial region; but the dryness of the columns of air which rise perpetually above the neighbouring plains of africa, and which the eastern winds convey with rapidity, gives to the atmosphere of the canary islands a transparency which not only surpasses that of the air of naples and sicily, but perhaps exceeds the purity of the sky of quito and peru. this transparency may be regarded as one of the chief causes of the beauty of landscape scenery in the torrid zone; it heightens the splendour of the vegetable colouring, and contributes to the magical effect of its harmonies and contrasts. if the mass of light, which circulates about objects, fatigues the external senses during a part of the day, the inhabitant of the southern climates has his compensation in moral enjoyment. a lucid clearness in the conceptions, and a serenity of mind, correspond with the transparency of the surrounding atmosphere. we feel these impressions without going beyond the boundaries of europe. i appeal to travellers who have visited countries rendered famous by the great creations of the imagination and of art — the favoured climes of italy and greece.

we prolonged in vain our stay on the summit of the peak, awaiting the moment when we might enjoy the view of the whole of the archipelago of the fortunate islands:* we, however, descried palma, gomera, and the great canary, at our feet. the mountains of lancerota, free from vapours at sunrise, were soon enveloped in thick clouds. supposing only an ordinary refraction, the eye takes in, in calm weather, from the summit of the volcano, a surface of the globe of 5700 square leagues, equal to a fourth of the superficies of spain. the question has often been agitated, whether it be possible to perceive the coast of africa from the top of this colossal pyramid; but the nearest parts of that coast are still farther from teneriffe than 2° 49′, or 56 leagues. the visual ray of the horizon from the peak being 1 degree 57 minutes, cape bojador can be seen only on the supposition of its height being 200 toises above the level of the ocean. we are ignorant of the height of the black mountains near cape bojador, as well as of that peak, called by navigators the penon grande, farther to the south of this promontory. if the summit of the volcano of teneriffe were more accessible, we should observe without doubt, in certain states of the wind, the effects of an extraordinary refraction. on perusing what spanish and portuguese authors relate respecting the existence of the fabulous isle of san borondon, or antilia, we find that it is particularly the humid wind from west-south-west, which produces in these latitudes the phenomena of the mirage. we shall not however admit with m. vieyra, “that the play of the terrestrial refractions may render visible to the inhabitants of the canaries the islands of cape verd, and even the apalachian mountains of america.”*

[* of all the small islands of the canaries, the rock of the east is the only one which cannot be seen, even in fine weather, from the top of the peak. its distance is 3° 5′, while that of the salvage is only 2° 1 minute. the island of madeira, distant 4° 29′, would be visible, if its mountains were more than 3000 toises high.]

[* the american fruits, frequently thrown by the sea on the coasts of the islands of ferro and gomera, were formerly supposed to emanate from the plants of the island of san borondon. this island, said to be governed by an archbishop and six bishops, and which father feijoa believed to be the image of the island of ferro, reflected on a fog-bank, was ceded in the 16th century, by the king of portugal, to lewis perdigon, at the time the latter was preparing to take possession of it by conquest.]

the cold we felt on the top of the peak, was very considerable for the season. the centigrade thermometer, at a distance from the ground, and from the apertures that emitted the hot vapours, fell in the shade to 2.7°. the wind was west, and consequently opposite to that which brings to teneriffe, during a great part of the year, the warm air that floats above the burning desert of africa. as the temperature of the atmosphere, observed at the port of orotava by m. savagi, was 22.8°, the decrement of caloric was one degree every 94 toises. this result perfectly corresponds with those obtained by lamanon and saussure on the summits of the peak and etna, though in very different seasons. the tall slender form of these mountains facilitates the means of comparing the temperature of two strata of the atmosphere, which are nearly in the same perpendicular plane; and in this point of view the observations made in an excursion to the volcano of teneriffe resemble those of an ascent in a balloon. we must nevertheless remark, that the ocean, on account of its transparency and evaporation, reflects less caloric than the plains, into the upper regions of the air; and also that summits which are surrounded by the sea are colder in summer, than mountains which rise from a continent; but this circumstance has very little influence on the decrement of atmospherical heat; the temperature of the low regions being equally diminished by the proximity of the ocean.

it is not the same with respect to the influence exercised by the direction of the wind, and the rapidity of the ascending current; the latter sometimes increases in an astonishing manner the temperature of the loftiest mountains. i have seen the thermometer rise, on the slope of the volcano of antisana, in the kingdom of quito, to 19°, when we were 2837 toises high. m. labillardiere has seen it, on the edge of the crater of the peak of teneriffe, at 18.7°, though he had used every possible precaution to avoid the effect of accidental causes.

on the summit of the peak, we beheld with admiration the azure colour of the sky. its intensity at the zenith appeared to correspond to 41° of the cyanometer. we know, by saussure’s experiment, that this intensity increases with the rarity of the air, and that the same instrument marked at the same period 39° at the priory of chamouni, and 40° at the top of mont blanc. this last mountain is 540 toises higher than the volcano of teneriffe; and if, notwithstanding this difference, the sky is observed there to be of a less deep blue, we must attribute this phenomenon to the dryness of the african air, and the proximity of the torrid zone.

we collected on the brink of the crater, some air which we meant to analyse on our voyage to america. the phial remained so well corked, that on opening it ten days after, the water rushed in with impetuosity. several experiments, made by means of nitrous gas in the narrow tube of fontana’s eudiometer, seemed to prove that the air of the crater contained 0.09° less oxygen than the air of the sea; but i have little confidence in this result obtained by means which we now consider as very inexact. the crater of the peak has so little depth, and the air is renewed with so much facility, that it is scarcely probable the quantity of azote is greater there than on the coasts. we know also, from the experiments of mm. gay–lussac and theodore de saussure, that in the highest as well as in the lowest regions of the atmosphere, the air equally contains 0.21 of oxygen.*

[* during the stay of m. gay–lussac and myself at the hospice of mont cenis, in march 1805, we collected air in the midst of a cloud loaded with electricity. this air, analysed in volta’s eudiometer, contained no hydrogen, and its purity did not differ 0.002 of oxygen from the air of paris, which we had carried with us in phials hermetically sealed.]

we saw on the summit of the peak no trace of psora, lecidea, or other cryptogamous plants; no insect fluttered in the air. we found however a few hymenoptera adhering to masses of sulphur moistened with sulphurous acid, and lining the mouths of the funnels. these are bees, which appear to have been attracted by the flowers of the spartium nubigenum, and which oblique currents of air had carried up to these high regions, like the butterflies found by m. ramond at the top of mont perdu. the butterflies perished from cold, while the bees on the peak were scorched on imprudently approaching the crevices where they came in search of warmth.

notwithstanding the heat we felt in our feet on the edge of the crater, the cone of ashes remains covered with snow during several months in winter. it is probable, that under the cap of snow considerable hollows are found, like those existing under the glaciers of switzerland, the temperature of which is constantly less elevated than that of the soil on which they repose. the cold and violent wind, which blew from the time of sunrise, induced us to seek shelter at the foot of the piton. our hands and faces were nearly frozen, while our boots were burnt by the soil on which we walked. we descended in the space of a few minutes the sugar-loaf which we had scaled with so much toil; and this rapidity was in part involuntary, for we often rolled down on the ashes. it was with regret that we quitted this solitude, this domain where nature reigns in all her majesty. we consoled ourselves with the hope of once again visiting the canary islands, but this, like many other plans we then formed, has never been executed.

we traversed the malpays but slowly; for the foot finds no sure foundation on the loose blocks of lava. nearer the station of the rocks, the descent becomes extremely difficult; the compact short-swarded turf is so slippery, that we were obliged to incline our bodies continually backward, in order to avoid falling. in the sandy plain of retama, the thermometer rose to 22.5°; and this heat seemed to us suffocating in comparison with the cold, which we had suffered from the air on the summit of the volcano. we were absolutely without water; our guides, not satisfied with drinking clandestinely the little supply of malmsey wine, for which we were indebted to don cologan’s kindness, had broken our water jars. happily the bottle which contained the air of the crater escaped unhurt.

we at length enjoyed the refreshing breeze in the beautiful region of the arborescent erica and fern; and we were enveloped in a thick bed of clouds stationary at six hundred toises above the plain. the clouds having dispersed, we remarked a phenomenon which afterwards became familiar to us on the declivities of the cordilleras. small currents of air chased trains of cloud with unequal velocity, and in opposite directions: they bore the appearance of streamlets of water in rapid motion and flowing in all directions, amidst a great mass of stagnant water. the causes of this partial motion of the clouds are probably very various; we may suppose them to arise from some impulsion at a great distance; from the slight inequalities of the soil, which reflects in a greater or less degree the radiant heat; from a difference of temperature kept up by some chemical action; or perhaps from a strong electric charge of the vesicular vapours.

as we approached the town of orotava, we met great flocks of canaries.* these birds, well known in europe, were in general uniformly green. some, however, had a yellow tinge on their backs; their note was the same as that of the tame canary. it is nevertheless remarked, that those which have been taken in the island of the great canary, and in the islet of monte clara, near lancerota, have a louder and at the same time a more harmonious song. in every zone, among birds of the same species, each flock has its peculiar note. the yellow canaries are a variety, which has taken birth in europe; and those we saw in cages at orotava and santa cruz had been bought at cadiz, and in other ports of spain. but of all the birds of the canary islands, that which has the most heart-soothing song is unknown in europe. it is the capirote, which no effort has succeeded in taming, so sacred to his soul is liberty. i have stood listening in admiration of his soft and melodious warbling, in a garden at orotava; but i have never seen him sufficiently near to ascertain to what family he belongs. as to the parrots, which were supposed to have been seen at the period of captain cook’s abode at teneriffe, they never existed but in the narratives of a few travellers, who have copied from each other. neither parrots nor monkeys inhabit the canary islands; and though in the new continent the former migrate as far as north carolina, i doubt whether in the old they have ever been met with beyond the 28th degree of north latitude.

[* fringilla canaria. la caille relates, in the narrative of his voyage to the cape, that on salvage island these canaries are so abundant, that you cannot walk there in a certain season without breaking their eggs.]

toward the close of day we reached the port of orotava, where we received the unexpected intelligence that the pizarro would not set sail till the 24th or 25th. if we could have calculated on this delay, we should either have lengthened our stay on the peak,* or have made an excursion to the volcano of chahorra. we passed the following day in visiting the environs of orotava, and enjoying the agreeable company we found at don cologan’s. we perceived that teneriffe had attractions not only to those who devote themselves to the study of nature: we found at orotava several persons possessing a taste for literature and music, and who have transplanted into these distant climes the amenity of european society. in these respects the canary islands have no great resemblance to the other spanish colonies, excepting the havannah.

[* as a great number of travellers who land at santa cruz, do not undertake the excursion to the peak, because they are ignorant of the time it occupies, it may be useful to lay down the following data: in making use of mules as far as the estancia de los ingleses, it takes twenty-one hours from orotava to arrive at the summit of the peak, and return to the port; namely, from orotava to the pino del dornajito three hours; from the pino to the station of the rocks six hours; and from this station to the caldera three hours and a half. i reckon nine hours for the descent. in this calculation i count only the time employed in walking, without reckoning that which is necessary for examining the productions of the peak, or for taking rest. half a day is sufficient for going from santa cruz to orotava.]

we were present on the eve of st. john at a pastoral fete in the garden of mr. little. this gentleman, who rendered great service to the canarians during the last famine, has cultivated a hill covered with volcanic substances. he has formed in this delicious site an english garden, whence there is a magnificent view of the peak, of the villages along the coast, and the isle of palma, which is bounded by the vast expanse of the atlantic. i cannot compare this prospect with any, except the views of the bays of genoa and naples; but orotava is greatly superior to both in the magnitude of the masses and in the richness of vegetation. in the beginning of the evening the slope of the volcano exhibited on a sudden a most extraordinary spectacle. the shepherds, in conformity to a custom, no doubt introduced by the spaniards, though it dates from the highest antiquity, had lighted the fires of st. john. the scattered masses of fire and the columns of smoke driven by the wind, formed a fine contrast with the deep verdure of the forests which covered the sides of the peak. shouts of joy resounding from afar were the only sounds that broke the silence of nature in these solitary regions.

don cologan’s family has a country-house nearer the coast than that i have just mentioned. this house, called la paz, is connected with a circumstance that rendered it peculiarly interesting to us. m. de borda, whose death we deplored, was its inmate during his last visit to the canary islands. it was in a neighbouring plain that he measured the base, by which he determined the height of the peak. in this geometrical operation the great dracaena of orotava served as a mark. should any well-informed traveller at some future day undertake a new measurement of the volcano with more exactness, and by the help of astronomical repeating circles, he ought to measure the base, not near orotava, but near los silos, at a place called bante. according to m. broussonnet there is no plain near the peak of greater extent. in herborizing near la paz we found a great quantity of lichen roccella on the basaltic rocks bathed by the waters of the sea. the archil of the canaries is a very ancient branch of commerce; this lichen is however found in less abundance in the island of teneriffe than in the desert islands of salvage, la graciosa, and alegranza, or even in canary and hierro. we left the port of orotava on the 24th of june.

to avoid disconnecting the narrative of the excursion to the top of the peak, i have said nothing of the geological observations i made on the structure of this colossal mountain, and on the nature of the volcanic rocks of which it is composed. before we quit the archipelago of the canaries, i shall linger for a moment, and bring into one point of view some facts relating to the physical aspect of those countries.

mineralogists who think that the end of the geology of volcanoes is the classification of lavas, the examination of the crystals they contain, and their description according to their external characters, are generally very well satisfied when they come back from the mouth of a burning volcano. they return loaded with those numerous collections, which are the principal objects of their research. this is not the feeling of those who, without confounding descriptive mineralogy (oryctognosy) with geognosy, endeavour to raise themselves to ideas generally interesting, and seek, in the study of nature, for answers to the following questions:—

is the conical mountain of a volcano entirely formed of liquified matter heaped together by successive eruptions, or does it contain in its centre a nucleus of primitive rocks covered with lava, which are these same rocks altered by fire? what are the affinities which unite the productions of modern volcanoes with the basalts, the phonolites, and those porphyries with bases of feldspar, which are without quartz, and which cover the cordilleras of peru and mexico, as well as the small groups of the monts dores, of cantal, and of mezen in france? has the central nucleus of volcanoes been heated in its primitive position, and raised up, in a softened state, by the force of the elastic vapours, before these fluids communicated, by means of a crater, with the external air? what is the substance, which, for thousands of years, keeps up this combustion, sometimes so slow, and at other times so active? does this unknown cause act at an immense depth; or does this chemical action take place in secondary rocks lying on granite?

the farther we are from finding a solution of these problems in the numerous works hitherto published on etna and vesuvius, the greater is the desire of the traveller to see with his own eyes. he hopes to be more fortunate than those who have preceded him; he wishes to form a precise idea of the geological relations which the volcano and the neighbouring mountains bear to each other: but how often is he disappointed, when, on the limits of the primitive soil, enormous banks of tufa and puzzolana render every observation on the position and stratification impossible! we reach the inside of the crater with less difficulty than we at first expect; we examine the cone from its summit to its base; we are struck with the difference in the produce of each eruption, and with the analogy which still exists between the lavas of the same volcano; but, notwithstanding the care with which we interrogate nature, and the number of partial observations which present themselves at every step, we return from the summit of a burning volcano less satisfied than when we were preparing to visit it. it is after we have studied them on the spot, that the volcanic phenomena appear still more isolated, more variable, more obscure, than we imagine them when consulting the narratives of travellers.

these reflections occurred to me on descending from the summit of the peak of teneriffe, the first unextinct volcano i had yet visited. they returned anew whenever, in south america, or in mexico, i had occasion to examine volcanic mountains. when we reflect how little the labours of mineralogists, and the discoveries in chemistry, have promoted the knowledge of the physical geology of mountains, we cannot help being affected with a painful sentiment; and this is felt still more strongly by those, who, studying nature in different climates, are more occupied by the problems they have not been able to solve, than with the few results they have obtained.

the peak of ayadyrma, or of echeyde,* is a conic and isolated mountain, which rises in an islet of very small circumference. those who do not take into consideration the whole surface of the globe, believe, that these three circumstances are common to the greater part of volcanoes. they cite, in support of their opinion, etna, the peak of the azores, the solfatara of guadaloupe, the trois–salazes of the isle of bourbon, and the clusters of volcanoes in the indian sea and in the atlantic. in europe and in asia, as far as the interior of the latter continent is known, no burning volcano is situated in the chains of mountains; all being at a greater or less distance from those chains. in the new world, on the contrary, (and this fact deserves the greatest attention,) the volcanoes the most stupendous for their masses form a part of the cordilleras themselves. the mountains of mica-slate and gneiss in peru and new grenada immediately touch the volcanic porphyries of the provinces of quito and pasto. to the south and north of these countries, in chile and in the kingdom of guatimala, the active volcanoes are grouped in rows. they are the continuation, as we may say, of the chains of primitive rocks, and if the volcanic fire has broken forth in some plain remote from the cordilleras, as in mount sangay and jorullo,* we must consider this phenomenon as an exception to the law, which nature seems to have imposed on these regions. i may here repeat these geological facts, because this presumed isolated situation of every volcano has been cited in opposition to the idea that the peak of teneriffe, and the other volcanic summits of the canary islands, are the remains of a submerged chain of mountains. the observations which have been made on the grouping of volcanoes in america, prove that the ancient state of things represented in the conjectural map of the atlantic by m. bory de st. vincent* is by no means contradictory to the acknowledged laws of nature; and that nothing opposes the supposition that the summits of porto santo, madeira, and the fortunate islands, may heretofore have formed, either a distinct range of primitive mountains, or the western extremity of the chain of the atlas.

[* the word echeyde, which signifies hell in the language of the guanches, has been corrupted by the europeans into teyde.]

[* two volcanoes of the provinces of quixos and mechoacan, the one in the southern, and the other in the northern hemisphere.]

[* whether the traditions of the ancients respecting the atlantis are founded on historical facts, is a matter totally distinct from the question whether the archipelago of the canaries and the adjacent islands are the vestiges of a chain of mountains, rent and sunk in the sea during one of the great convulsions of our globe. i do not pretend to form any opinion in favour of the existence of the atlantis; but i endeavour to prove, that the canaries have no more been created by volcanoes, than the whole body of the smaller antilles has been formed by madrepores.]

the peak of teyde forms a pyramidal mass like etna, tungurahua, and popocatepetl. this physiognomic character is very far from being common to all volcanoes. we have seen some in the southern hemisphere, which, instead of having the form of a cone or a bell, are lengthened in one direction, having the ridge sometimes smooth, and at others bristled with small pointed rocks. this structure is peculiar to antisana and pichincha, two burning mountains of the province of quito; and the absence of the conic form ought never to be considered as a reason excluding the idea of a volcanic origin. i shall develop, in the progress of this work, some of the analogies, which i think i have perceived between the physiognomy of volcanoes and the antiquity of their rocks. it is sufficient to state, generally speaking, that the summits, which are still subject to eruptions of the greatest violence, and at the nearest periods to each other, are slender peaks of a conic form; that the mountains with lengthened summits, and rugged with small stony masses, are very old volcanoes, and near being extinguished; and that rounded tops, in the form of domes, or bells, indicate those problematic porphyries, which are supposed to have been heated in their primitive position, penetrated by vapours, and forced up in a mollified state, without having ever flowed as real lithoidal lavas. to the first class belong cotopaxi, the peak of teneriffe, and the peak of orizava in mexico. in the second may be placed cargueirazo and pichincha, in the province of quito; the volcano of puracey, near popayan; and perhaps also hecla, in iceland. in the third and last we may rank the majestic figure of chimborazo, and, (if it be allowable to place by the side of that colossus a hill of europe,) the great sarcouy in auvergne.

in order to form a more exact idea of the external structure of volcanoes, it is important to compare their perpendicular height with their circumference. this, however, cannot be done with any exactness, unless the mountains are isolated, and rising on a plain nearly on a level with the sea. in calculating the circumference of the peak of teneriffe in a curve passing through the port of orotava, garachico, adexe, and guimar, and setting aside the prolongations of its base towards the forest of laguna, and the north-east cape of the island, we find that this extent is more than 54,000 toises. the height of the peak is consequently one twenty-eighth of the circumference of its basis. m. von buch found a thirty-third for vesuvius; and, which perhaps is less certain, a thirty-fourth for etna.* if the slope of these three volcanoes were uniform from the summit to the base, the peak of teyde would have an inclination of 12° 29′, vesuvius 12° 41′, and etna 10° 13′, a result which must astonish those who do not reflect on what constitutes an average slope. in a very long ascent, slopes of three or four degrees alternate with others which are inclined from 25 to 30°; and the latter only strike our imagination, because we think all the slopes of mountains more steep than they really are. i may cite in support of this consideration the example of the ascent from the port of vera cruz to the elevated plain of mexico. on the eastern slope of the cordillera a road has been traced, which for ages has not been frequented except on foot, or on the backs of mules. from encero to the small indian village of las vigas, there are 7500 toises of horizontal distance; and encero being, according to my barometric measurement, 746 toises lower than las vigas, the result, for the mean slope, is only an angle of 5° 40′.

[* gilbert, annalen der physik b. 5 page 455. vesuvius is 133,000 palmas, or eighteen nautical miles in circumference. the horizontal distance from resina to the crater is 3700 toises. italian mineralogists have estimated the circumference of etna at 840,000 palmas, or 119 miles. with these data, the ratio of the height to the circumference would be only a seventy-second; but i find on tracing a curve through catania, palermo, bronte, and piemonte, only 62 miles in circumference, according to the best maps. this increases the ratio to a fifty-fourth. does the basis fall on the outside of the curve that i assume?]

in the following note will be seen the results of some experiments i have made on the difficulties arising from the declivities in mountainous countries.*

[* in places where there were at the same time slopes covered with tufted grass and loose sands, i took the following measures:—

5°, slope of a very marked inclination. in france the high

roads must not exceed 4° 46′ by law;

15°, slope extremely steep, and which we cannot descend in a

carriage;

37°, slope almost inaccessible on foot, if the ground be

naked rock, or turf too thick to form steps. the body falls

backwards when the tibia makes a smaller angle than 53° with

the sole of the foot;

42°, the steepest slope that can be climbed on foot in a

ground that is sandy, or covered with volcanic ashes.

when the slope is 44°, it is almost impossible to scale it, though the ground permits the forming of steps by thrusting in the foot. the cones of volcanoes have a medium slope from 33 to 40°. the steepest parts of these cones, either of vesuvius, the peak of teneriffe, the volcano of pichincha, or jorullo, are from 40 to 42°. a slope of 55° is quite inaccessible. if seen from above it would be estimated at 75°.]

isolated volcanoes, in the most distant regions, are very analogous in their structure. at great elevations all have considerable plains, in the middle of which arises a cone perfectly circular. thus at cotopaxi the plains of suniguaicu extend beyond the farm of pansache. the stony summit of antisana, covered with eternal snow, forms an islet in the midst of an immense plain, the surface of which is twelve leagues square, while its height exceeds that of the peak of teneriffe by two hundred toises. at vesuvius, at three hundred and seventy toises high, the cone detaches itself from the plain of atrio dei cavalli. the peak of teneriffe presents two of these elevated plains, the uppermost of which, at the foot of the piton, is as high as etna, and of very little extent; while the lowermost, covered with tufts of retama, reaches as far as the estancia de los ingleses. this rises above the level of the sea almost as high as the city of quito, and the summit of mount lebanon.

the greater the quantity of matter that has issued from the crater of a mountain, the more elevated is its cone of ashes in proportion to the perpendicular height of the volcano itself. nothing is more striking, under this point of view, than the difference of structure between vesuvius, the peak of teneriffe, and pichincha. i have chosen this last volcano in preference, because its summit* enters scarcely within the limit of the perpetual snows. the cone of cotopaxi, the form of which is the most elegant and most regular known, is 540 toises in height; but it is impossible to decide whether the whole of this mass is covered with ashes.

[* i have measured the summit of pichincha, that is the small mountain covered with ashes above the llano del vulcan, to the north of alto de chuquira. this mountain has not, however, the regular form of a cone. as to vesuvius, i have indicated the mean height of the sugar-loaf, on account of the great difference between the two edges of the crater.]

name of the volcano. total height in toises. height of the cone covered with ashes. proportion of the cone to the total height.

vesuvius 606 200 1/3.

peak of teneriffe 1904 84 1/22.

pichincha 2490 240 1/10.

this table seems to indicate, what we shall have an opportunity of proving more amply hereafter, that the peak of teneriffe belongs to that group of great volcanoes, which, like etna and antisana, have had more copious eruptions from their sides than from their summits. thus the crater at the extremity of the piton, which is called the caldera, is extremely small. its diminutive size struck m. de borda, and other travellers, who took little interest in geological investigations.

as to the nature of the rocks which compose the soil of teneriffe, we must first distinguish between productions of the present volcano, and the range of basaltic mountains which surround the peak, and which do not rise more than five or six hundred toises above the level of the ocean. here, as well as in italy, mexico, and the cordilleras of quito, the rocks of trap-formation* are at a distance from the recent currents of lava; everything shows that these two classes of substances, though they owe their origin to similar phenomena, date from very different periods. it is important to geology not to confound the modern currents of lava, the heaps of basalt, green-stone, and phonolite, dispersed over the primitive and secondary formations, with those porphyroid masses having bases of compact feldspar,* which perhaps have never been perfectly liquified, but which do not less belong to the domain of volcanoes.

[* the trap-formation includes the basalts, green-stone (grunstein), the trappean porphyries, the phonolites or porphyrschiefer, etc.]

[* these petrosiliceous masses contain vitreous and often calcined crystals of feldspar, of amphibole, of pyroxene, a little of olivine, but scarcely any quartz. to this very ambiguous formation belong the trappean porphyries of chimborazo and of riobamba in america, of the euganean mountains in italy, and of the siebengebirge in germany; as well as the domites of the great–sarcouy, of puy-dedome, of the little cleirsou, and of one part of the puy–chopine in auvergne.]

in the island of teneriffe, strata of tufa, puzzolana, and clay, separate the range of basaltic hills from the currents of recent lithoid lava, and from the eruptions of the present volcano. in the same manner as the eruptions of epomeo in the island of ischia, and those of jorullo in mexico, have taken place in countries covered with trappean porphyry, ancient basalt, and volcanic ashes, so the peak of teyde has raised itself amidst the wrecks of submarine volcanoes. notwithstanding the difference of composition in the recent lavas of the peak, there is a certain regularity of position, which must strike the naturalist least skilled in geognosy. the great elevated plain of retama separates the black, basaltic, and earthlike lava, from the vitreous and feldsparry lava, the basis of which is obsidian, pitch-stone, and phonolite. this phenomenon is the more remarkable, inasmuch as in bohemia and in other parts of europe, the porphyrschiefer with base of phonolite* covers also the convex summits of basaltic mountains.

[* klingstein. werner.]

it has already been observed, that from the level of the sea to portillo, and as far as the entrance on the elevated plain of the retama, that is, two-thirds of the total height of the volcano, the ground is so covered with plants, that it is difficult to make geological observations. the currents of lava, which we discover on the slope of monte verde, between the beautiful spring of dornajito and caravela, are black masses, altered by decomposition, sometimes porous, and with very oblong pores. the basis of these lower lavas is rather wacke than basalt; when it is spongy, it resembles the amygdaloids* of frankfort-on-the-main. its fracture is generally irregular; wherever it is conchoidal, we may presume that the cooling has been more rapid, and the mass has been exposed to a less powerful pressure. these currents of lava are not divided into regular prisms, but into very thin layers, not very regular in their inclination; they contain much olivine, small grains of magnetic iron, and augite, the colour of which often varies from deep leek-green to olive green, and which might be mistaken for crystallized olivine, though no transition from one to the other of these substances exists.* amphibole is in general very rare at teneriffe, not only in the modern lithoid lavas, but also in the ancient basalts, as has been observed by m. cordier, who resided longer at the canaries than any other mineralogist. nepheline, leucite, idocrase, and meionite have not yet been seen at the peak of teneriffe; for a reddish-grey lava, which we found on the slope of monte verde, and which contains small microscopic crystals, appears to me to be a close mixture of basalt and analcime.* in like manner the lava of scala, with which the city of naples is paved, contains a close mixture of basalt, nepheline, and leucite. with respect to this last substance, which has hitherto been observed only at vesuvius and in the environs of rome, it exists perhaps at the peak of teneriffe, in the old currents of lava now covered by more recent ejections. vesuvius, during a long series of years, has also thrown out lavas without leucites: and if it be true, as m. von buch has rendered very probable, that these crystals are formed only in the currents which flow either from the crater itself, or very near its brink, we must not be surprised at not finding them in the lavas of the peak. the latter almost all proceed from lateral eruptions, and consequently have been exposed to an enormous pressure in the interior of the volcano.

[* wakkenartiger mandelstein. steinkaute.]

[* steffens, handbuch der oryktognosie tome 1 s. 364. the crystals which mr. friesleben and myself have made known under the denomination of foliated olivine (blattriger olivin) belong, according to mr. karsten, to the pyroxene augite. journal des mines de freiberg 1791 page 215.]

[* this substance, which m. dolomieu discovered in the amygdaloids of catania in sicily, and which accompanies the stilbites of fassa in tyrol, forms, with the chabasie of hauy, the genus cubicit of werner. m. cordier found at teneriffe xeolite in an amygdaloid which covers the basalts of la punta di naga.]

in the plain of retama, the basaltic lavas disappear under heaps of ashes, and pumice-stone reduced to powder. thence to the summit, from 1500 to 1900 toises in height, the volcano exhibits only vitreous lava with bases of pitch-stone* and obsidian. these lavas, destitute of amphibole and mica, are of a blackish brown, often varying to the deepest olive green. they contain large crystals of feldspar, which are not fissured, and seldom vitreous. the analogy of those decidedly volcanic masses with the resinite porphyries* of the valley of tribisch in saxony is very remarkable; but the latter, which belong to an extended and metalliferous formation of porphyry, often contain quartz, which is wanting in the modern lavas. when the basis of the lavas of the malpays changes from pitchstone to obsidian, its colour is paler, and is mixed with grey; in this case, the feldspar passes by imperceptible gradations from the common to the vitreous. sometimes both varieties meet in the same fragment, as we observed also in the trappean porphyries of the valley of mexico. the feldsparry lavas of the peak, of a much less black tinge than those of arso in the island of ischia, whiten at the edge of the crater from the effect of the acid vapours; but internally they are not found to be colourless like that of the feldsparry lavas of the solfatara at naples, which perfectly resemble the trappean porphyries at the foot of chimborazo. in the middle of the malpays, at the height of the cavern of ice, we found among the vitreous lavas with pitch-stone and obsidian bases, blocks of real greenish-grey, or mountain-green phonolite, with a smooth fracture, and divided into thin laminae, sonorous and keen edged. these masses were the same as the porphyrschiefer of the mountain of bilin in bohemia; we recognised in them small long crystals of vitreous feldspar.

[* petrosilex resinite. hauy.]

[* pechstein-porphyr. werner.]

this regular disposition of lithoid basaltic lava and feldsparry vitreous lava is analogous to the phenomena of all trappean mountains; it reminds us of those phonolites lying in very ancient basalts, those close mixtures of augite and feldspar which cover the hills of wacke or porous amygdaloids: but why are the porphyritic or feldsparry lavas of the peak found only on the summit of the volcano? should we conclude from this position that they are of more recent formation than the lithoid basaltic lava, which contains olivine and augite? i cannot admit this last hypothesis; for lateral eruptions may have covered the feldsparry nucleus, at a period when the crater had ceased its activity. at vesuvius also, we perceive small crystals of vitreous feldspar only in the very ancient lavas of the somma. these lavas, setting aside the leucite, very nearly resemble the phonolitic ejections of the peak of teneriffe. in general, the farther we go back from the period of modern eruptions, the more the currents increase both in size and extent, acquiring the character of rocks, by the regularity of their position, by their division into parallel strata, or by their independence of the present form of the ground.

the peak of teneriffe is, next to lipari, the volcano that has produced most obsidian. this abundance is the more striking, as in other regions of the earth, in iceland, in hungary, in mexico, and in the kingdom of quito, we meet with obsidians only at great distances from burning volcanoes. sometimes they are scattered over the fields in angular pieces; for instance, near popayan, in south america; at other times they form isolated rocks, as at quinche, near quito. in other places (and this circumstance is very remarkable), they are disseminated in pearl-stone, as at cinapecuaro, in the province of mechoacan,* and at the cabo de gates, in spain. at the peak of teneriffe the obsidian is not found towards the base of the volcano, which is covered with modern lava: it is frequent only towards the summit, especially from the plain of retama, where very fine specimens may be collected. this peculiar position, and the circumstance that the obsidian of the peak has been ejected by a crater which for ages past has thrown out no flames, favour the opinion, that volcanic vitrifications, wherever they are found, are to be considered as of very ancient formation.

[* to the west of the city of mexico.]

obsidian, jade, and lydian-stone,* are three minerals, which nations ignorant of the use of copper or iron, have in all ages employed for making keen-edged weapons. we see that wandering hordes have dragged with them, in their distant journeys, stones, the natural position of which the mineralogist has not yet been able to determine. hatchets of jade, covered with aztec hieroglyphics, which i brought from mexico, resemble both in their form and nature those made use of by the gauls, and those we find among the south sea islanders. the mexicans dug obsidian from mines, which were of vast extent; and they employed it for making knives, sword-blades, and razors. in like manner the guanches, (in whose language obsidian was called tabona,) fixed splinters of that mineral to the ends of their lances. they carried on a considerable trade in it with the neighbouring islands; and from the consumption thus occasioned, and the quantity of obsidian which must have been broken in the course of manufacture, we may presume that this mineral has become scarce from the lapse of ages. we are surprised to see an atlantic nation substituting, like the natives of america, vitrified lava for iron. in both countries this variety of lava was employed as an object of ornament: and the inhabitants of quito made beautiful looking-glasses with an obsidian divided into parallel laminae.

[* lydischerstein.]

there are three varieties of obsidian at the peak. some form enormous blocks, several toises long, and often of a spheroidal shape. we might suppose that they had been thrown out in a softened state, and had afterwards been subject to a rotary motion. they contain a quantity of vitreous feldspar, of a snow-white colour, and the most brilliant pearly lustre. these obsidians are, nevertheless, but little transparent on the edges; they are almost opaque, of a brownish black, and of an imperfect conchoidal fracture. they pass into pitch-stone; and we may consider them as porphyries with a basis of obsidian. the second variety is found in fragments much less considerable. it is in general of a greenish black, sometimes of murky grey, very seldom of a perfect black, like the obsidian of hecla and mexico. its fracture is perfectly conchoidal, and it is extremely transparent on the edges. i have found in it neither amphibole nor pyroxene, but some small white points, which seem to be feldspar. none of the obsidians of the peak appear in those grey masses of pearl or lavender-blue, striped, and in separate wedge-formed pieces, like the obsidian of quito, mexico, and lipari, and which resemble the fibrous plates of the crystalites of our glass-houses, on which sir james hall, dr. thompson, and m. de bellevue, have published some curious observations.*

[* the name crystalites has been given to the crystalized thin plates observed in glass cooling slowly. the term glastenized glass is employed by dr. thompson and others to indicate glass which by slow cooling is wholly unvitrified, and has assumed the appearance of a fossil substance, or real glass-stone.]

the third variety of obsidian of the peak is the most remarkable of the whole, from its connexion with pumice-stone. it is, like that above described, of a greenish black, sometimes of a murky grey, but its very thin plates alternate with layers of pumice-stone. dr. thomson’s fine collection at naples contained similar examples of lithoid lava of vesuvius, divided into very distinct plates, only a line thick. the fibres of the pumice-stone of the peak are very seldom parallel to each other, and perpendicular to the strata of obsidian; they are most commonly irregular, asbestoidal, like fibrous glass-gall; and instead of being disseminated in the obsidian, like crystalites, they are found simply adhering to one of the external surfaces of this substance. during my stay at madrid, m. hergen showed me several specimens in the mineralogical collection of don jose clavijo; and for a long time the spanish mineralogists considered them as furnishing undoubted proofs, that pumice-stone owes its origin to obsidian, in some degree deprived of colour, and swelled by volcanic fire. i was formerly of this opinion, which, however, must be understood to refer to one variety only of pumice. i even thought, with many other geologists, that obsidian, so far from being vitrified lava, belonged to rocks that were not volcanic; and that the fire, forcing its way through the basalts, the green-stone rocks, the phonolites, and the porphyries with bases of pitchstone and obsidian, the lavas and pumice-stone were no other than these same rocks altered by the action of the volcanoes. the deprivation of colour and extraordinary swelling which the greater part of the obsidians undergo in a forge-fire, their transition into pitch-stone, and their position in regions very distant from burning volcanoes, appear to be phenomena very difficult to reconcile, when we consider the obsidians as volcanic glass. a more profound study of nature, new journeys, and observations made on the productions of burning volcanoes, have led me to renounce those ideas.

it appears to me at present extremely probable, that obsidians, and porphyries with bases of obsidian, are vitrified masses, the cooling of which has been too rapid to change them into lithoid lava. i consider even the pearlstone as an unvitrified obsidian: for among the minerals in the king’s cabinet at berlin there are volcanic glasses from lipari, in which we see striated crystalites, of a pearl-grey colour, and of an earthy appearance, forming gradual approaches to a granular lithoid lava, like the pearlstone of cinapecuaro, in mexico. the oblong bubbles observed in the obsidians of every continent are incontestible proofs of their ancient state of igneous fluidity; and dr. thompson possesses specimens from lipari, which are very instructive in this point of view, because fragments of red porphyry, or porphyry lavas, which do not entirely fill up the cavities of the obsidian, are found enveloped in them. we might say, that these fragments had not time to enter into complete solution in the liquified mass. they contain vitreous feldspar, and augite, and are the same as the celebrated columnar porphyries of the island of panaria, which, without having been part of a current of lava, seem raised up in the form of hillocks, like many of the porphyries in auvergne, in the euganean mountains, and in the cordilleras of the andes.

the objections against the volcanic origin of obsidians, founded on their speedy loss of colour, and their swelling by a slow fire, have been shaken by the ingenious experiments of sir james hall. these experiments prove, that a stone which is fusible only at thirty-eight degrees of wedgwood’s pyrometer, yields a glass that softens at fourteen degrees; and that this glass, melted again and unvitrified (glastenized), is fusible again only at thirty-five degrees of the same pyrometer. i applied the blowpipe to some black pumice-stone from the volcano of the isle of bourbon, which, on the slightest contact with the flame, whitened and melted into an enamel.

but whether obsidians be primitive rocks which have undergone the action of volcanic fire, or lavas repeatedly melted within the crater, the origin of the pumice-stones contained in the obsidian of the peak of teneriffe is not less problematic. this subject is the more worthy of being investigated, since it is generally interesting to the geology of volcanoes; and since that excellent mineralogist, m. fleuriau de bellevue, after having examined italy and the adjacent islands with great attention, affirms, that it is highly improbable that pumice-stone owes its origin to the swelling of obsidian.

the experiments of m. da camara, and those i made in 1802, tend to support the opinion, that the pumice-stones adherent to the obsidians of the peak of teneriffe do not unite to them accidentally, but are produced by the expansion of an elastic fluid, which is disengaged from the compact vitreous matter. this idea had for a long time occupied the mind of a person highly distinguished for his talents and reputation at quito, who, unacquainted with the labours of the mineralogists of europe, had devoted himself to researches on the volcanoes of his country. don juan de larea, one of those men lately sacrificed to the fury of faction, had been struck with the phenomena exhibited by obsidians exposed to a white heat. he had thought, that, wherever volcanoes act in the centre of a country covered with porphyry with base of obsidian, the elastic fluids must cause a swelling of the liquified mass, and perform an important part in the earthquakes preceding eruptions. without adopting an opinion, which seems somewhat bold, i made, in concert with m. larea, a series of experiments on the tumefaction of the volcanic vitreous substances at teneriffe, and on those which are found at quinche, in the kingdom of quito. to judge of the augmentation of their bulk, we measured pieces exposed to a forge-fire of moderate heat, by the water they displaced from a cylindric glass, enveloping the spongy mass with a thin coating of wax. according to our experiments, the obsidians swelled very unequally: those of the peak and the black varieties of cotopaxi and of quinche increased nearly five times their bulk.

the colour of the pumice-stones of the peak leads to another important observation. the sea of white ashes which encircles the piton, and covers the vast plain of retama, is a certain proof of the former activity of the crater: for in all volcanoes, even when there are lateral eruptions, the ashes and the rapilli issue conjointly with the vapours only from the opening at the summit of the mountain. now, at teneriffe, the black rapilli extend from the foot of the peak to the sea-shore; while the white ashes, which are only pumice ground to powder, and among which i have discovered, with a lens, fragments of vitreous feldspar and pyroxene, exclusively occupy the region next to the peak. this peculiar distribution seems to confirm the observations made long ago at vesuvius, that the white ashes are thrown out last, and indicate the end of the eruption. in proportion as the elasticity of the vapours diminishes, the matter is thrown to a less distance; and the black rapilli, which issue first, when the lava has ceased running, must necessarily reach farther than the white rapilli. the latter appear to have been exposed to the action of a more intense fire.

i have now examined the exterior structure of the peak, and the composition of its volcanic productions, from the region of the coast to the top of the piton:— i have endeavoured to render these researches interesting, by comparing the phenomena of the volcano of teneriffe with those that are observed in other regions, the soil of which is equally undermined by subterranean fires. this mode of viewing nature in the universality of her relations is no doubt adverse to the rapidity desirable in an itinerary; but it appears to me that, in a narrative, the principal end of which is the progress of physical knowledge, every other consideration ought to be subservient to those of instruction and utility. by isolating facts, travellers, whose labours are in every other respect valuable, have given currency to many false ideas of the pretended contrasts which nature offers in africa, in new holland, and on the ridge of the cordilleras. the great geological phenomena are subject to regular laws, as well as the forms of plants and animals. the ties which unite these phenomena, the relations which exist between the varied forms of organized beings, are discovered only when we have acquired the habit of viewing the globe as a great whole; and when we consider in the same point of view the composition of rocks, the causes which alter them, and the productions of the soil, in the most distant regions.

having treated of the volcanic substances of the isle of teneriffe, there now remains to be solved a question intimately connected with the preceding investigation. does the archipelago of the canary islands contain any rocks of primitive or secondary formation; or is there any production observed, that has not been modified by fire? this interesting problem has been considered by the naturalists of lord macartney’s expedition, and by those who accompanied captain baudin in his voyage to the austral regions. their opinions are in direct opposition to each other; and the contradiction is the more striking, as the question does not refer to one of those geological reveries which we are accustomed to call systems, but to a positive fact.

doctor gillan imagined that he observed, between laguna and the port of orotava, in very deep ravines, beds of primitive rocks. this, however, is a mistake. what dr. gillan calls somewhat vaguely, mountains of hard ferruginous clay, are nothing but an alluvium which we find at the foot of every volcano. strata of clay accompany basalts, as tufas accompany modern lavas. neither m. cordier nor myself observed in any part of teneriffe a primitive rock, either in its natural place, or thrown out by the mouth of the peak; and the absence of these rocks characterizes almost every island of small extent that has an unextinguishied volcano. we know nothing positive of the mountains of the azores; but it is certain, that the island of bourbon as well as teneriffe, exhibits only a heap of lavas and basalts. no volcanic rock rears its head, either on the gros morne, or on the volcano of bourbon, or on the colossal pyramid of cimandef, which is perhaps more elevated than the peak of the canary islands.

bory st. vincent nevertheless asserted, that lavas including fragments of granite have been found on the elevated plain of retama; and m. broussonnet informed me, that on a hill above guimar, fragments of mica-slate, containing beautiful plates of specular iron, had been found. i can affirm nothing respecting the accuracy of this latter statement, which it would be so much the more important to verify, as m. poli, of naples, is in possession of a fragment of rock thrown out by vesuvius,* which i found to be a real mica-slate. every thing that tends to enlighten us with respect to the site of the volcanic fire, and the position of rocks subject to its action, is highly interesting to geology.

[* in the valuable collection of dr. thomson, who resided at naples till 1805, is a fragment of lava enclosing a real granite, which is composed of reddish feldspar with a pearly lustre like adularia, quartz, mica, hornblende, and, what is very remarkable, lazulite. but in general the masses of known primitive rocks, (i mean those which perfectly resemble our granites, our gneiss, and our mica-slates) are very rare in lavas; the substances we commonly denote by the name of granite, thrown out by vesuvius, are mixtures of nepheline, mica, and pyroxene. we are ignorant whether these mixtures constitute rocks sui generis placed under granite, and consequently of more ancient date; or simply form either intermediate strata on veins, in the interior of the primitive mountains, the tops of which appear at the surface of the globe.]

it is possible, that at the peak of teneriffe, the fragments of primitive rocks thrown out by the mouth of the volcano may be less rare than they at present appear to be, and may be heaped together in some ravine, not yet visited by travellers. in fact, at vesuvius, these same fragments are met with only in one single place, at the fossa grande, where they are hidden under a thick layer of ashes. if this ravine had not long ago attracted the attention of naturalists, when masses of granular limestone, and other primitive rocks, were laid bare by the rains, we might have thought them as rare at vesuvius, as they are, at least in appearance, at the peak of teneriffe.

with respect to the fragments of granite, gneiss, and mica-slate, found on the shores of santa cruz and orotava, they were probably brought in ships as ballast. they no more belong to the soil where they lie, than the feldsparry lavas of etna, seen in the pavements of hamburg and other towns of the north. the naturalist is exposed to a thousand errors, if he lose sight of the changes, produced on the surface of the globe by the intercourse between nations. we might be led to say, that man, when expatriating himself; is desirous that everything should change country with him. not only plants, insects, and different species of small quadrupeds, follow him across the ocean; his active industry covers the shores with rocks, which he has torn from the soil in distant climes.

though it be certain, that no scientific observer has hitherto found at teneriffe primitive strata, or even those trappean and ambiguous porphyries, which constitute the bases of etna, and of several volcanoes of the andes, we must not conclude from this isolated fact, that the whole archipelago of the canaries is the production of submarine fires. the island of gomera contains mountains of granite and mica-slate; and it is, undoubtedly, in these very ancient rocks, that we must seek there, as well as on all other parts of the globe, the centre of the volcanic action. amphibole, sometimes pure and forming intermediate strata, at other times mixed with granite, as in the basanites or basalts of the ancients, may, of itself, furnish all the iron contained in the black and stony lavas. this quantity amounts in the basalt of the modern mineralogists only to 0.20, while in amphibole it exceeds 0. 30.

from several well-informed persons, to whom i addressed myself, i learned that there are calcareous formations in the great canary, forteventura, and lancerota.* i was not able to determine the nature of this secondary rock; but it appears certain, that the island of teneriffe is altogether destitute of it; and that in its alluvial lands it exhibits only clayey calcareous tufa, alternating with volcanic breccia, said to contain, (near the village of la rambla, at calderas, and near candelaria,) plants, imprints of fishes, buccinites, and other fossil marine productions. m. cordier brought away some of this tufa, which resembles that in the environs of naples and rome, and contains fragments of reeds. at the salvages, which islands la perouse took at a distance for masses of scoriae, even fibrous gypsum is found.

[* at lancerota calcareous stone is burned to lime with a fire made of the alhulaga, a new species of thorny and arborescent sonchus.]

i had seen, while herborizing between the port of orotava and the garden of la paz, heaps of greyish calcareous stones, of an imperfect conchoidal fracture, and analogous to that of mount jura and the apennines. i was informed that these stones were extracted from a quarry near rambla; and that there were similar quarries near realejo, and the mountain of roxas, above adexa. this information led me into an error. as the coasts of portugal consist of basalts covering calcareous rocks containing shells, i imagined that a trappean formation, like that of the vicentin in lombardy, and of harutsh in africa, might have extended from the banks of the tagus and cape st. vincent as far as the canary islands; and that the basalts of the peak might perhaps conceal a secondary calcareous stone. these conjectures exposed me to severe animadversions from m. g.a. de luc, who is of opinion that every volcanic island is only an accumulation of lavas and scoriae. m. de luc declares it is impossible that real lava should contain fragments of vegetable substances. our collections, however, contain pieces of trunks of palm-trees, enclosed and penetrated by the very liquid lava of the isle of bourbon.

though teneriffe belongs to a group of islands of considerable extent, the peak exhibits nevertheless all the characteristics of a mountain rising on a solitary islet. the lead finds no bottom at a little distance from the ports of santa cruz, orotava, and garachico: in this respect it is like st. helena. the ocean, as well as the continents, has its mountains and its plains; and, if we except the andes, volcanic cones are formed everywhere in the lower regions of the globe.

as the peak rises amid a system of basalts and old lava, and as the whole part which is visible above the surface of the waters exhibits burnt substances, it has been supposed that this immense pyramid is the effect of a progressive accumulation of lavas; or that it contains in its centre a nucleus of primitive rocks. both of these suppositions appear to me ill-founded. i think there is as little probability that mountains of granite, gneiss, or primitive calcareous stone have existed where we now see the tops of the peak, of vesuvius, and of etna, as in the plains where almost in our own time has been formed the volcano of jorullo, which is more than a third of the height of vesuvius. on examining the circumstances which accompanied the formation of the new island, called sabrina, in the archipelago of the azores;* on carefully reading the minute and simple narrative, given by the jesuit bourguignon of the slow appearance of the islet of the little kameni, near santorino; we find that these extraordinary eruptions are generally preceded by a swelling of the softened crust of the globe. rocks appear above the waters before the flames force their way, or lavas issue from the crater: we must distinguish between the nucleus raised up, and the mass of lavas and scoriae, which successively increases its dimensions.

[* at sabrina island, near st. michael’s, the crater opened at the foot of a solid rock, of almost a cubical form. this rock, surmounted by a small elevated plain perfectly level, is more than two hundred toises in breadth. its formation was anterior to that of the crater, into which, a few days after its opening, the sea made an irruption. at kameni, the smoke was not even visible till twenty-six days after the appearance of the upheaved rocks. philosophical transactions volume 26 pages 69 and 200, volume 27 page 353. all these phenomena, on which mr. hawkins collected very valuable observations during his abode at santorino, are unfavourable to the idea commonly entertained of the origin of volcanic mountains. they are usually ascribed to a progressive accumulation of liquified matter, and the diffusion of lavas issuing from a central mouth.]

it is true that from all existing records of revolutions of this kind, the perpendicular height of the stony nucleus appears never to have exceeded one hundred and fifty or two hundred toises; even taking into the account the depth of the sea, the bottom of which had been lifted up: but when considering the great effects of nature, and the intensity of its forces, the bulk of the masses must not deter the geologist in his speculations. every thing indicates that the physical changes of which tradition has preserved the remembrance, exhibit but a feeble image of those gigantic catastrophes which have given mountains their present form, changed the positions of the rocky strata, and buried sea-shells on the summits of the higher alps. doubtless, in those remote times which preceded the existence of the human race, the raised crust of the globe produced those domes of trappean porphyry, those hills of isolated basalt on vast elevated plains, those solid nuclei which are clothed in the modern lavas of the peak, of etna, and of cotopaxi. the volcanic revolutions have succeeded each other after long intervals, and at very different periods: of this we see the vestiges in the transition mountains, in the secondary strata, and in those of alluvium. volcanoes of earlier date than the sandstone and calcareous rocks have been for ages extinguished; those which are yet in activity are in general surrounded only with breccias and modern tufas; but nothing hinders us from admitting, that the archipelago of the canaries may exhibit some real rocks of secondary formation, if we recollect that subterranean fires have been there rekindled in the midst of a system of basalts and very ancient lavas.

we seek in vain in the periplus of hanno or of scylax for the first written notions on the eruptions of the peak of teneriffe. those navigators sailed timidly along the coast, anchoring every evening in some bay, and had no knowledge of a volcano distant fifty-six leagues from the coast of africa. hanno nevertheless relates, that he saw torrents of light, which seemed to fall on the sea; that every night the coast was covered with fire; and that the great mountain, called the car of the gods, appeared to throw up sheets of flame, which rose even to the clouds. but this mountain, situated northward of the island of the gorilli, formed the western extremity of the atlas chain; and it is also very uncertain whether the flames seen by hanno were the effect of some volcanic eruption, or whether they must be attributed to the custom, common to many nations, of setting fire to the forests and dry grass of the savannahs. in our own days similar doubts were entertained by the naturalists, who, in the voyage of d’entrecasteaux, saw the island of amsterdam covered with a thick smoke. on the coast of the caracas, trains of reddish fire, fed by the burning grass, appeared to me, for several nights, under the delusive semblance of a current of lava, descending from the mountains, and dividing itself into several branches.

though the narratives of hanno and scylax, in the state in which they have reached us, contain no passage which we can reasonably apply to the canary islands, it is very probable that the carthaginians, and even the phoenicians, had some knowledge of the peak of teneriffe. in the time of plato and aristotle, vague notions of it had reached the greeks, who considered the whole of the coast of africa, beyond the pillars of hercules, as thrown into disorder by the fire of volcanoes. the abode of the blessed, which was sought first in the north, beyond the riphaean mountains, among the hyperboreans, and next to the south of cyrenaica, was supposed to be situated in regions that were considered to be westward, being the direction in which the world known to the ancients terminated. the name of fortunate islands was long in as vague signification, as that of el dorado among the conquerors of america. happiness was thought to reside at the end of the earth, as we seek for the most exquisite enjoyments of the mind in an ideal world beyond the limits of reality.*

[* the idea of the happiness, the great civilization, and the riches of the inhabitants of the north, was common to the greeks, to the people of india, and to the mexicans.]

we must not be surprised that, previous to the time of aristotle, we find no accurate notion respecting the canary islands and the volcanoes they contain, among the greek geographers. the only nation whose navigations extended toward the west and the north, the carthaginians, were interested in throwing a veil of mystery over those distant regions. while the senate of carthage was averse to any partial emigration, it pointed out those islands as a place of refuge in times of trouble and public misfortune; they were to the carthaginians what the free soil of america has become to europeans amidst their religious and civil dissensions.

the canaries were not better known to the romans till eighty-four years before the reign of augustus. a private individual was desirous of executing the project, which wise foresight had dictated to the senate of carthage. sertorius, conquered by sylla, and weary of the din of war, looked out for a safe and peaceable retreat. he chose the fortunate islands, of which a delightful picture had been drawn for him on the shores of baetica. he carefully combined the notions he acquired from travellers; but in the little that has been transmitted to us of those notions, and in the more minute descriptions of sebosus and juba, there is no mention of volcanoes or volcanic eruptions. scarcely can we recognise the isle of teneriffe, and the snows with which the summit of the peak is covered in winter, in the name of nivaria, given to one of the fortunate islands. hence we might conclude, that the volcano at that time threw out no flames, if it were allowable so to interpret the silence of a few authors, whom we know only by short fragments or dry nomenclatures. the naturalist vainly seeks in history for documents of the first eruptions of the peak; he nowhere finds any but in the language of the guanches, in which the word echeyde denotes, at the same time, hell and the volcano of teneriffe.

of all the written testimonies, the oldest i have found in relation to the activity of this volcano dates from the beginning of the sixteenth century. it is contained in the narrative of the voyage of aloysio cadamusto, who landed at the canaries in 1505. this traveller was witness of no eruptions, but he positively affirms that, like etna, this mountain burns without interruption, and that the fire has been seen by christians held in slavery by the guanches of teneriffe. the peak, therefore, was not at that time in the state of repose in which we find it at present; for it is certain that no navigator or inhabitant of teneriffe has seen issue from the mouth of the peak, i will not say flames, but even any smoke visible at a distance. it would be well, perhaps, were the funnel of the caldera to open anew; the lateral eruptions would thereby be rendered less violent, and the whole group of islands would be less endangered by earthquakes.

the eruptions of the peak have been very rare for two centuries past, and these long intervals appear to characterize volcanoes highly elevated. the smallest one of all, stromboli, is almost always burning. at vesuvius, the eruptions are rarer than formerly, though still more frequent than those of etna and the peak of teneriffe. the colossal summits of the andes, cotopaxi and tungurahua, scarcely have an eruption once in a century. we may say, that in active volcanoes the frequency of the eruptions is in the inverse ratio of the height and the mass. the peak also had seemed extinguished during ninety-two years, when, in 1798, it made its last eruption by a lateral opening formed in the mountain of chahorra. in this interval vesuvius had sixteen eruptions.

the whole of the mountainous part of the kingdom of quito may be considered as an immense volcano, occupying more than seven hundred square leagues of surface, and throwing out flames by different cones, known under the particular denominations of cotopaxi, tungurahua, and pichincha. the group of the canary islands is situated on the same sort of submarine volcano. the fire makes its way sometimes by one and sometimes by another of these islands. teneriffe alone contains in its centre an immense pyramid terminating in a crater, and throwing out, from one century to another, lava by its flanks. in the other islands, the different eruptions have taken place in various parts; and we nowhere find those isolated mountains to which the volcanic effects are confined. the basaltic crust, formed by ancient volcanoes, seems everywhere undermined; and the currents of lava, seen at lancerota and palma, remind us, by every geological affinity, of the eruption which took place in 1301 at the island of ischia, amid the tufas of epomeo.

the exclusively lateral action of the peak of teneriffe is a geological phenomenon, the more remarkable as it contributes to make the mountains which are backed by the principal volcano appear isolated. it is true, that in etna and vesuvius the great flowings of lava do not proceed from the crater itself, and that the abundance of melted matter is generally in the inverse ratio of the height of the opening whence the lava is ejected. but at vesuvius and etna a lateral eruption constantly terminates by flashes of flame and by ashes issuing from the crater, that is, from the summit of the mountain. at the peak this phenomenon has not been witnessed for ages: and yet recently, in the eruption of 1798, the crater remained quite inactive. its bottom did not sink in; while at vesuvius, as m. von buch has observed, the greater or less depth of the crater is an infallible indication of the proximity of a new eruption.

i might terminate these geological sketches by enquiring into the nature of the combustible which has fed for so many thousands of years the fire of the peak of teneriffe; — i might examine whether it be sodium or potassium, the metallic basis of some earth, carburet of hydrogen, or pure sulphur combined with iron, that burns in the volcano; — but wishing to limit myself to what may be the object of direct observation, i shall not take upon me to solve a problem for which we have not yet sufficient data. we know not whether we may conclude, from the enormous quantity of sulphur contained in the crater of the peak, that it is this substance which keeps up the heat of the volcano; or whether the fire, fed by some combustible of an unknown nature, effects merely the sublimation of the sulphur. what we learn from observation is, that in craters which are still burning, sulphur is very rare; while all the ancient volcanoes end in becoming sulphur-pits. we might presume that, in the former, the sulphur is combined with oxygen, while, in the latter, it is merely sublimated; for nothing hitherto authorises us to admit that it is formed in the interior of volcanoes, like ammonia and the neutral salts. when we were yet unacquainted with sulphur, except as disseminated in the muriatiferous gypsum and in the alpine limestone, we were almost forced to the belief, that in every part of the globe the volcanic fire acted on rocks of secondary formation; but recent observations have proved that sulphur exists in great abundance in those primitive rocks which so many phenomena indicate as the centre of the volcanic action. near alausi, at the back of the andes of quito, i found an immense quantity in a bed of quartz, which formed a layer of mica-slate. this fact is the more important, as it is in strict conformity with the conclusions deduced from the observation of those fragments of ancient rocks which are thrown out intact by volcanoes.

we have just considered the island of teneriffe merely in a geological point of view; we have seen the peak towering amid fractured strata of basalt and mandelstein; let us examine how these fused masses have been gradually adorned with vegetable clothing, what is the distribution of plants on the steep declivity of the volcano, and what is the aspect or physiognomy of vegetation in the canary islands.

in the northern part of the temperate zone, the cryptogamous plants are the first that cover the stony crust of the globe. the lichens and mosses, that develop their foliage beneath the snows, are succeeded by grumina and other phanerogamous plants. this order of vegetation differs on the borders of the torrid zone, and in the countries between the tropics. we there find, it is true, whatever some travellers may have asserted, not only on the mountains, but also in humid and shady places, almost on a level with the sea, funaria, dicranum, and bryum; and these genera, among their numerous species, exhibit several which are common to lapland, to the peak of teneriffe, and to the blue mountains of jamaica. (this extraordinary fact was first observed by m. swarz. it was confirmed by m. willdenouw when he carefully examined our herbals, especially the collection of cryptogamous plants, which we gathered on the tops of the andes, in a region of the world where organic life is totally different from that of the old world.) nevertheless, in general, it is not by mosses and lichens that vegetation in the countries near the tropics begins. in the canary islands, as well as in guinea, and on the rocky coasts of peru, the first vegetation which prepares the soil are the succulent plants; the leaves of which, provided with an infinite number of orifices* and cutaneous vessels, deprive the ambient air of the water it holds in solution. fixed in the crevices of volcanic rocks, they form, as it were, that first layer of vegetable earth with which the currents of lithoid lava are clothed. wherever these lavas are scorified, and where they have a shining surface, as in the basaltic mounds to the north of lancerota, the development of vegetation is extremely slow, and many ages may pass away before shrubs can take root. it is only when lavas are covered with tufa and ashes, that the volcanic islands, losing that appearance of nudity which marks their origin, bedeck themselves in rich and brilliant vegetation.

[* the pores corticaux of m. decandolle, discovered by gleichen, and figured by hedwig.]

in its present state, the island of teneriffe, the chinerfe* of the guanches, exhibits five zones of plants, which we may distinguish by the names — region of vines, region of laurels, region of pines, region of the retama, and region of grasses. these zones are ranged in stages, one above another, and occupy, on the steep declivity of the peak, a perpendicular height of 1750 toises; while fifteen degrees farther north, on the pyrenees, snow descends to thirteen or fourteen hundred toises of absolute elevation. if the plants of teneriffe do not reach the summit of the volcano, it is not because the perpetual snow and the cold of the surrounding atmosphere mark limits which they cannot pass; it is the scorified lava of the malpays, the powdered and barren pumice-stone of the piton, which impede the migration of plants towards the brink of the crater.

[* of chinerfe the europeans have formed, by corruption, tchineriffe and teneriffe.]

the first zone, that of the vines, extends from the sea-shore to two or three hundred toises of height; it is that which is most inhabited, and the only part carefully cultivated. in the low regions, at the port of orotava, and wherever the winds have free access, the centigrade thermometer stands in winter, in the months of january and february, at noon, between fifteen and seventeen degrees; and the greatest heats of summer do not exceed twenty-five or twenty-six degrees. the mean temperature of the coasts of teneriffe appears at least to rise to twenty-one degrees (16.8° reaumur); and the climate in those parts keeps at the medium between the climate of naples and that of the torrid zone.

the region of the vines exhibits, among its vegetable productions, eight kinds of arborescent euphorbia; mesembrianthema, which are multiplied from the cape of good hope to the peloponnesus; the cacalia kleinia, the dracaena, and other plants, which in their naked and tortuous trunks, in their succulent leaves, and their tint of bluish green, exhibit distinctive marks of the vegetation of africa. it is in this zone that the date-tree, the plantain, the sugar-cane, the indian fig, the arum colocasia, the root of which furnishes a nutritive fecula, the olive-tree, the fruit trees of europe, the vine, and corn are cultivated. corn is reaped from the end of march to the beginning of may: and the culture of the bread-fruit tree of otaheite, that of the cinnamon tree of the moluccas, the coffee-tree of arabia, and the cacao-tree of america, have been tried with success. on several points of the coast the country assumes the character of a tropical landscape; and we perceive that the region of the palms extends beyond the limits of the torrid zone. the chamaerops and the date-tree flourish in the fertile plains of murviedro, on the coasts of genoa, and in provence, near antibes, between the thirty-ninth and forty-fourth degrees of latitude; a few trees of the latter species, planted within the walls of the city of rome, resist even the cold of 2.5° below freezing point. but if the south of europe as yet only partially shares the gifts lavished by nature on the zone of palms, the island of teneriffe, situated on the parallel of egypt, southern persia, and florida, is adorned with the greater part of the vegetable forms which add to the majesty of the landscape in the regions near the equator.

on reviewing the different tribes of indigenous plants, we regret not finding trees with small pinnated leaves, and arborescent gramina. no species of the numerous family of the sensitive-plants has migrated as far as the archipelago of the canary islands, while on both continents they have been seen in the thirty-eighth and fortieth degrees of latitude. on a more careful examination of the plants of the islands of lancerota and forteventura, which are nearest the coast of morocco, we may perhaps find a few mimosas among many other plants of the african flora.

the second zone, that of the laurels, comprises the woody part of teneriffe: this is the region of the springs, which gush forth amidst turf always verdant, and never parched with drought. lofty forests crown the hills leading to the volcano, and in them are found four species of laurel,* an oak nearly resembling the quercus turneri* of the mountains of tibet, the visnea mocanera, the myrica faya of the azores, a native olive (olea excelsa), which is the largest tree of this zone, two species of sideroxylon, the leaves of which are extremely beautiful, the arbutus callicarpa, and other evergreen trees of the family of myrtles. bindweeds, and an ivy very different from that of europe (hedera canariensis) entwine the trunks of the laurels; at their feet vegetate a numberless quantity of ferns,* of which three species* alone descend as low as the region of the vines. the soil, covered with mosses and tender grass, is enriched with the flowers of the campanula aurea, the chrysanthemum pinnatifidum, the mentha canariensis, and several bushy species of hypericum.* plantations of wild and grafted chestnut-trees form a broad border round the region of the springs, which is the greenest and most agreeable of the whole.

[* laurus indica, l. foetens, l. nobilis, and l. til. with these trees are mingled the ardisia excelsa, rhamnus glandulosus, erica arborea and e. texo.]

[* quercus canariensis, broussonnet.]

[* woodwardia radicans, asplenium palmatum, a. canariensis, a. latifolium, nothalaena subcordata, trichomanes canariensis, t. speciosum, and davallia canariensis.]

[* two acrostichums and the ophyoglossum lusitanicum.]

[* hypericum canariense, h. floribundum, and h. glandulosum.]

in the third zone (beginning at nine hundred toises of absolute height), the last groups of arbutus, of myrica faya, and of that beautiful heath known to the natives by the name of texo, appear. this zone, four hundred toises in breadth, is entirely filled by a vast forest of pines, among which mingles the juniperus cedro of broussonnet. the leaves of these pines are very long and stiff, and they sprout sometimes by pairs, but oftener by threes in one sheath. having had no opportunity of examining the fructification, we cannot say whether this species, which has the appearance of the scotch fir, is really different from the eighteen species of pines with which we are already acquainted in europe. m. decandolle is of opinion that the pine of teneriffe is equally distinct from the pinus atlantica of the neighbouring mountains of mogador, and from the pine of aleppo,* which belongs to the basin of the mediterranean, and does not appear to have passed the pillars of hercules. we met with these last pines on the slope of the peak, near twelve hundred toises above the level of the sea. in the cordilleras of new spain, under the torrid zone, the mexican pines extend to the height of two thousand toises. notwithstanding the similarity of structure existing between the different species of the same genus of plants, each of them requires a certain degree of temperature and rarity in the ambient air to attain its due growth. if in temperate climates, and wherever snow falls, the uniform heat of the soil be somewhat above the mean heat of the atmosphere, it is probable that at the height of portillo the roots of the pines draw their nourishment from a soil, in which, at a certain depth, the thermometer rises at most to nine or ten degrees.

[* pinus halepensis. m. decandolle observes, that this species, which is not found in portugal, but grows on the mediterranean shores of france, spain, and italy, in asia minor, and in barbary, would be better named pinus mediterranea. it composes the principal part of the pine-forests of the south-east of france, where gouan and gerard have confounded it with the pinus sylvestris. it comprehends the pinus halepensis, mill., lamb., and desfont., and the pinus maritima, lamb.]

the fourth and fifth zones, the regions of the retama and the gramina, occupy heights equal to the most inaccessible summits of the pyrenees. it is the sterile part of the island where heaps of pumice-stone, obsidian, and broken lava, form impediments to vegetation. we have already spoken of those flowery tufts of alpine broom (spartium nubigenum), which form oases amidst a vast desert of ashes. two herbaceous plants, the scrophularia glabrata and the viola cheiranthifolia, advance even to the malpays. above a turf scorched by the heat of an african sun, an arid soil is overspread by the cladonia paschalis. towards the summit of the peak the urceolarea and other plants of the family of the lichens, help to work the decomposition of the scorified matter. by this unceasing action of organic force the empire of flora is extended over islands ravaged by volcanoes.

on surveying the different zones of the vegetation of teneriffe, we perceive that the whole island may be considered as a forest of laurels, arbutus, and pines, containing in its centre a naked and rocky soil, unfit either for pasturage or cultivation. m. broussonnet observes, that the archipelago of the canaries may be divided into two groups of islands; the first comprising lancerota and forteventura, the second teneriffe, canary, gomera, ferro, and palma. the appearance of the vegetation essentially differs in these two groups. the eastern islands, lancerota and forteventura, consist of extensive plains and mountains of little elevation; they have very few springs, and bear the appearance, still more than the other islands, of having been separated from the continent. the winds blow in the same direction, and at the same periods: the euphorbia mauritanica, the atropa frutescens, and the arborescent sonchus, vegetate there in the loose sands, and afford, as in africa, food for camels. the western group of the canaries presents a more elevated soil, is more woody, and is watered by a greater number of springs.

though the whole archipelago contains several plants found also in portugal,* in spain, at the azores, and in the north-west of africa, yet a great number of species, and even some genera, are peculiar to teneriffe, to porto santo, and to madeira. such are the mocanera, the plocama, the bosea, the canarina, the drusa, and the pittosporum. a form which may be called northern, that of the cruciform plant (among the small number of cruciform species contained in the flora of teneriffe, we shall here mention cheiranthus longifolius, l’herit.; ch. fructescens, vent.; ch. scoparius, brouss.; erysimum bicorne, aiton; crambe strigosa, and c. laevigata, brouss.), is much rarer in the canaries than in spain and in greece. still farther to the south, in the equinoctial regions of both continents, where the mean temperature of the air rises above twenty-two degrees, the cruciform plants are scarcely ever to be seen.

[* m. willdenouw and myself found, among the plants of the peak of teneriffe, the beautiful satyrium diphyllum (orchis cordata, willd.) which mr. link discovered in portugal. the canaries have, in common with the flora of the azores, not the dicksonia culcita, the only arborescent heath found at the thirty-ninth degree of latitude, but the asplenium palmatum, and the myrica faya. this last tree is met with in portugal, in a wild state. count hoffmansegg has seen very old trunks of it; but it was doubtful whether it was indigenous, or imported into that part of our continent. in reflecting on the migrations of plants, and on the geological possibility, that lands sunk in the ocean may have heretofore united portugal, the azores, the canaries, and the chain of atlas, we conceive, that the existence of the myrica faya in western europe is a phenomenon at least as striking as that of the pine of aleppo would be at the azores.]

a question highly interesting to the history of the progressive marks of organization on the globe has been very warmly discussed in our own times, that of ascertaining whether the polymorphous plants are more common in the volcanic islands. the vegetation of teneriffe is unfavourable to the hypothesis that nature in new countries is but little subject to permanent forms. m. broussonnet, who resided so long at the canaries, asserts that the variable plants are not more common there than in the south of europe. may it not to be presumed, that the polymorphous species, which are so abundant in the isle of bourbon, are assignable to the nature of the soil and climate rather than to the newness of the vegetation?

before we take leave of the old world to pass into the new, i must advert to a subject which is of general interest, because it belongs to the history of man, and to those fatal revolutions which have swept off whole tribes from the face of the earth. we inquire at the isle of cuba, at st. domingo, and in jamaica, where is the abode of the primitive inhabitants of those countries? we ask at teneriffe what is become of the guanches, whose mummies alone, buried in caverns, have escaped destruction? in the fifteenth century almost all mercantile nations, especially the spaniards and the portuguese, sought for slaves at the canary islands, as in later times they have been sought on the coast of guinea.* the christian religion, which in its origin was so highly favourable to the liberty of mankind, served afterwards as a pretext to the cupidity of europeans. every individual, made prisoner before he received the rite of baptism, became a slave. at that period no attempt had yet been made to prove that the blacks were an intermediate race between man and animals. the swarthy guanche and the african negro were simultaneously sold in the market of seville, without a question whether slavery should be the doom only of men with black skins and woolly hair.

[* the spanish historians speak of expeditions made by the huguenots of rochelle to carry off guanche slaves. i have some doubt respecting these expeditions, which are said to have taken place subsequently to the year 1530.]

the archipelago of the canaries was divided into several small states hostile to each other, and in many instances the same island was subject to two independent princes. the trading nations, influenced by the hideous policy still exercised on the coast of africa, kept up intestine warfare. one guanche then became the property of another, who sold him to the europeans; several, who preferred death to slavery, killed themselves and their children. the population of the canaries had considerably suffered by the slave trade, by the depredations of pirates, and especially by a long period of carnage, when alonzo de lugo completed the conquest of the guanches. the surviving remnants of the race perished mostly in 1494, in the terrible pestilence called the modorra, which was attributed to the quantity of dead bodies left exposed in the open air by the spaniards after the battle of la laguna. the nation of the guanches was extinct at the beginning of the seventeenth century; a few old men only were found at candelaria and guimar.

it is, however, consoling to find that the whites have not always disdained to intermarry with the natives; but the canarians of the present day, whom the spaniards familiarly call islenos (islanders), have very powerful motives for denying this mixture. in a long series of generations time effaces the characteristic marks of a race; and as the descendants of the andalusians settled at teneriffe are themselves of dark complexion, we may conceive that intermarriages cannot have produced a perceptible change in the colour of the whites. it is very certain that no native of pure race exists in the whole island. it is true that a few canarian families boast of their relationship to the last shepherd-king of guimar, but these pretensions do not rest on very solid foundations, and are only renewed from time to time when some canarian of more dusky hue than his countrymen is prompted to solicit a commission in the service of the king of spain.

a short time after the discovery of america, when spain was at the highest pinnacle of her glory, the gentle character of the guanches was the fashionable topic, as we in our times laud the arcadian innocence of the inhabitants of otaheite. in both these pictures the colouring is more vivid than true. when nations, wearied with mental enjoyments, behold nothing in the refinement of manners but the germ of depravity, they are pleased with the idea, that in some distant region, in the first dawn of civilization, infant society enjoys pure and perpetual felicity. to this sentiment tacitus owed a part of his success, when he sketched for the romans, subjects of the caesars, a picture of the manners of the inhabitants of germany. the same sentiment gives an ineffable charm to the narrative of those travellers who, at the close of the last century, visited the south sea islands.

the inhabitants of those islands, too much vaunted (and previously anthropophagi), resemble, under more than one point of view, the guanches of teneriffe. both nations were under the yoke of feudal government. among the guanches, this institution, which facilitates and renders a state of warfare perpetual, was sanctioned by religion. the priests declared to the people: “the great spirit, achaman, created first the nobles, the achimenceys, to whom he distributed all the goats that exist on the face of the earth. after the nobles, achaman created the plebeians, achicaxnas. this younger race had the boldness to petition also for goats; but the supreme spirit answered, that this race was destined to serve the nobles, and that they had need of no property.” this tradition was made, no doubt, to please the rich vassals of the shepherd-kings. the faycan, or high priest, also exercised the right of conferring nobility; and the law of the guanches expressed that every achimencey who degraded himself by milking a goat with his own hands, lost his claim to nobility. this law does not remind us of the simplicity of the homeric age. we are astonished to see the useful labours of agriculture, and of pastoral life, exposed to contempt at the very dawn of civilization.

the guanches, famed for their tall stature, were the patagonians of the old world. historians exaggerated the muscular strength of the guanches, as, previous to the voyage of bougainville and cordoba, colossal proportions were attributed to the tribe that inhabited the southern extremity of america. i never saw guanche mummies but in the cabinets of europe. at the time i visited the canaries they were very scarce; a considerable number, however, might be found if miners were employed to open the sepulchral caverns which are cut in the rock on the eastern slope of the peak, between arico and guimar. these mummies are in a state of desiccation so singular, that whole bodies, with their integuments, frequently do not weigh above six or seven pounds; or a third less than the skeleton of an individual of the same size, recently stripped of the muscular flesh. the conformation of the skull has some slight resemblance to that of the white race of the ancient egyptians; and the incisive teeth of the guanches are blunted, like those of the mummies found on the banks of the nile. but this form of teeth is the result of art; and on examining more carefully the physiognomy of the ancient canarians, blumenbach and other able anatomists have recognized in the cheek bones and the lower jaw perceptible differences from the egyptian mummies. on opening those of the guanches, remains of aromatic plants are discovered, among which the chenopodium ambrosioides is constantly perceived: the bodies are often decorated with small laces, to which are hung little discs of baked earth, which appear to have served as numerical signs, and resemble the quippoes of the peruvians, the mexicans, and the chinese.

the population of islands being in general less exposed than that of continents to the effect of migrations, we may presume that, in the time of the carthaginians and the greeks, the archipelago of the canaries was inhabited by the same race of men as were found by the norman and spanish conquerors. the only monument that can throw any light on the origin of the guanches is their language; but unhappily there are not above a hundred and fifty words extant, and several express the same object, according to the dialect of the different islanders. independently of these words, which have been carefully noted, there are still some valuable fragments existing in the names of a great number of hamlets, hills, and valleys. the guanches, like the biscayans, the hindoos, the peruvians, and all primitive nations, named places after the quality of the soil, the shape of the rocks, the caverns that gave them shelter, and the nature of the tree that overshadowed the springs.*

[* it has been long imagined, that the language of the guanches had no analogy with the living tongues; but since the travels of hornemann, and the ingenious researches of marsden and venturi, have drawn the attention of the learned to the berbers, who, like the sarmatic tribes, occupy an immense extent of country in the north of africa, we find that several guanche words have common roots with words of the chilha and gebali dialects. we shall cite, for instance, the words:

word. in guanche. in berberic.

heaven tigo tigot.

milk aho acho.

barley temasen tomzeen.

basket carianas carian.

water aenum anan.

i doubt whether this analogy is a proof of a common origin; but it is an indication of the ancient connexion between the guanches and berbers, a tribe of mountaineers, in which the ancient numidians, getuli, and garamanti are confounded, and who extend themselves from the eastern extremity of atlas by harutsh and fezzan, as far as the oasis of siwah and augela. the natives of the canary islands called themselves guanches, from guan, man; as the tonguese call themselves bye, and tongui, which have the same signification as guan. besides the nations who speak the berberic language are not all of the same race; and the description which scylax gives, in his periplus, of the inhabitants of cerne, a shepherd people of tall stature and long hair, reminds us of the features which characterize the canarian guanches.]

the greater attention we direct to the study of languages in a philosophical point of view, the more we must observe that no one of them is entirely distinct. the language of the guanches would appear still less so, had we any data respecting its mechanism and grammatical construction; two elements more important than the form of words, and the identity of sounds. it is the same with certain idioms, as with those organized beings that seem to shrink from all classification in the series of natural families. their isolated state is merely apparent; for it ceases when, on embracing a greater number of objects, we come to discover the intermediate links. those learned enquirers who trace egyptians wherever there are mummies, hieroglyphics, or pyramids, will imagine perhaps that the race of typhon was united to the guanches by the berbers, real atlantes, to whom belong the tibboes and the tuarycks of the desert: but this hypothesis is supported by no analogy between the berberic and coptic languages, which are justly considered as remnants of the ancient egyptian.

the people who have succeeded the guanches are descended from the spaniards, and in a more remote degree from the normans. though these two races have been exposed during three centuries past to the same climate, the latter is distinguished by the fairer complexion. the descendants of the normans inhabit the valley of teganana, between punta de naga and punta de hidalgo. the names of grandville and dampierre are still pretty common in this district. the canarians are a moral, sober, and religious people, of a less industrious character at home than in foreign countries. a roving and enterprising disposition leads these islanders, like the biscayans and catalonians, to the philippines, to the ladrone islands, to america, and wherever there are spanish settlements, from chile and la plata to new mexico. to them we are in a great measure indebted for the progress of agriculture in those colonies. the whole archipelago does not contain 160,030 inhabitants, and the islenos are perhaps more numerous in the new continent than in their own country.