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 degrees, 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 degrees, 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 degrees 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 degrees at the priory of Chamouni, and 40 degrees 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 degrees 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 degrees; 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.* (* 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.) 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.

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. (* 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 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.

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