The basalt of Pichincha, near the city of Quito, has an elevation of 15,500 feet; while the top of the Schneekoppe in Silesia, is only 4,225 feet above the sea, the highest point in Germany where that species of rock occurs. On the other hand, granite, which, in Europe, crowns the loftiest mountains, is not found in the American continent above the height of 11,500 feet. It is scarcely known at all in the provinces of Quito and Peru. The frozen summits of Chimborazo, Cayambé and Anitsana, consist entirely of porphyry, which, on the flanks of the Andes, forms a mass of 10 or 12,000 feet in depth. The sandstone near Cuença, has a thickness of 5,000 feet; and the stupendous mass of pure quartz, on the west of Caxamarca, measures perpendicularly 9,600 feet. It is likewise a remarkable fact, that the porphyry of those mountains very frequently contains hornblende, but never quartz, and seldom mica.

The central Andes are rich, beyond conception, in all the metals, lead only excepted. One of the most curious ores, in the bowels of those mountains, is the pacos, a compound of clay, oxyd of iron, and the muriate of silver with native silver. The mines of Mexico and Peru, so long the objects of envy and admiration, far from being yet exhausted, promise, under a liberal and improved system, to become more productive than ever. But nature has blended with those hidden treasures the active aliments of destruction. The whole chain of the Andes is subject to the most terrible earthquakes. From Cotopaxi to the South Sea, no fewer than forty volcanos are constantly burning; some of them, especially the lower ones, ejecting lava, and others discharging the muriate of ammonia, scorified basalt and porphyry, enormous quantities of water, and especially moya, or clay mixed with sulphur and carbonaceous matter. Eternal snow invests

their sides, and forms a barrier to the animal and vegetable kingdoms. Near that confine, the torpor of vegetation is marked by dreary wastes.

In these wide solitudes, the condor, a fierce and powerful bird of prey, fixes its gloomy abode. Its size, however, has been greatly exagge rated. According to Humboldt, it is not larger than the Lammer-Geyer, or alpine vulture of Europe; its extreme length being only three feet and a half, and its breadth across the wings nine feet. The condor pursues the small deer of the Andes, and commits very considerable havock among sheep and heifers. It tears out the eyes and the tongue, and leaves the wretched animal to languish and expire. Estimating from very probable data, this bird skims whole hours at the height of four miles; and its power of wing must be prodigious, and its pliancy of organs most astonishing, since in an instant it can dart from the chill region of mid air, to the sultry shores of the ocean.

The condor is sometimes caught alive by means of a slip cord; and this chase, termed correr buitres, is, next to a bull-fight, the most favourable diversion of the Spanish colonists. The dead carcase of a cow or horse soon attracts from a distance crowds of these birds, which have a most acute scent. They fall on with incredible voracity; devour the eyes and the tongue of the animal; and, plunging through the anus, gorge themselves with the entrails. In this drowsy plight, they are approached by the Indians, who easily throw a noose over them. The condor, thus entangled, looks shy and sullen; it is most tenacious of life, and is, therefore, made to suffer a variety of protracted tortures.

The most important feature of the American continent, is the very general and enormous elevation of its soil. In Europe, the highest tracts of cultivated land seldom rise more than 2,000 feet above the sea.

But, in the Peruvian territory, extensive plains occur at an altitude of 9,000 feet; and three fifths of the viceroyalty of Mexico, comprehending the interiour provinces, present a surface of half a million of square miles, which runs nearly level, at an elevation from 6,000 to 8,000 feet, equal to that of the celebrated passages of Mount Cenis, of St. Gothard, or of the Great St. Bernard. These remarkable facts are deduced chiefly from barometrical observations. But Humboldt has adopted a very ingenious mode, infinitely superiour to any description, of representing, at one view, the collective results of his topographical and mineralogical survey. He has given profiles, or vertical sections of the countries which he vesited; across the continent, from Acapulco to Mexico, and thence to Vera Cruzfrom Mexico to Guanaxuato, and as far as the volcano of Jorullo-and from Mexico to Valladolid. These beautiful plates are in every way highly interesting.

II. The Climate of America receives considerable elucidation from the travels of Humboldt. Near the equator, the variation of atmospherick pressure, as indicated by the barometer, is extremely small; not exceeding the tenth part of an inch towards the coast, and scarcely the half of that quantity on the verge of the Andes; but it appears to be subject to a minute horary fluctuation. According to the observations of Bonpland, the barometer stands highest at 9 o'clock in the morning, and lowest at 4 in the afternoon. From that hour, it rises very considerably until eleven at night, and again partially subsides till 4 o'clock in the morning. This curious phenomenon depends, most probably, on certain regular changes which take place in the temperature of the upper strata of the atmosphere. At 4 o'clock in the afternoon, perhaps the heat of the day has produced its full effect in rarefying the air, while

the condensation, occasioned by the chillness of the night, may not attain its maximum till three hours after sunrise. In confirmation of this idea, the barometer is at times observed to fall suddenly more than half an inch in the gulf of Mexico, from the influence of a cold wind which bursts from the north in tremendous hurricanes.

Thermometrical observations are, we think, the least satisfactory that Humboldt has made. Continually in motion, distracted by a variety of pursuits, and biassed by preconceived opinions, he has collected but few details of such nice accuracy, as to promise any great advancement to the science of meteorology. Near the equator, the temperature of the air, even on the continent, undergoes no great variation during the whole year, being very seldom below 65, or above one hundred degrees. The difference of heat, in the torrid regions, between the day and the night, was found to amount to 10 or 20 degrees.

But he assumes, it would seem, rather hastily, the average of his incidental observations at any place. as the true medium of its temperature. This standard, however, being evidently the result of the va rious influence of each successive hour through the whole course of the seasons in a long series of years, must often differ widely from a mean obtained at unequal intervals of the day, and at the times only most convenient for the observer. Since heat is conducted with extreme slowness through earth and stone, the varying impressions made on the surface of the ground, in penetrating down. wards, become mingled and confounded at a moderate depth, where a uniform temperature constantly prevails. The mean heat of any place is, therefore, best indicated, by wa ter immediately drawn up at a small distance from below the subsoil. With due precaution, springs will serve the same purpose. M. Hum

boldt, indeed, pretends, that, in the Campagna di Roma, and in the province of the Caraccas, he found the springs to be 10 degrees colder than the medium temperature. But, in his transient observations, he appears generally to have rated this mean too high.

The subject of climate, as yet so imperfectly understood, would afford room for much very interesting discussion. We shall, however, content ourselves at present with offering a few short remarks.

The mean temperature of any place depends on two distinct conditions, its distance from the equator, and its elevation above the sea. The warmth that vivifies our globe is all derived from the rays of the sun, which, being absorbed at the surface of the ground, and partly in the lower strata of the atmosphere, constitute the general mass of heat. But, in consequence of the obliquity of the earth's axis, combined with the effect of its rotundity, the proportion of light which falls in the various latitudes is most widely different. The solar action is hence shared out with such excessive inequality, that, if left to its unmitigated influence, the several climates on the surface of the globe would be divided by impassable zones. Our atmosphere, the great vehicle of impressions, performs that essential office; and, maintaining, by means of a complex system of winds, a slow yet continual intercourse between the equator and the poles, transports the heat of the south to the frozen regions of the north, and carries back the polar cold to fan the sultry face of the tropicks; thus blending the different effects, and attempering the general distribution of warmth. A fluid of greater mobility or conducting power would still further reduce the inequality of climates. Had the atmosphere consisted of hydrogen gas, the difference of temperature between the equator and the poles would have been three

times less than what obtains in the actual constitution of our globe. From these principles, the law of temperature, as dependent on latitude, may be determined, agreeing with the formula discovered by the celebrated Mayer of Gottingen, which, with a slight modification, corresponds with the most precise observations. We should expect the mean temperature of Vera Cruz to be 78 1-2 degrees. Humboldt, from a register kept there for several years, states it at 78°; but the heat of Callao, the port of Lima, which ought to be 82°, is, apparently on very slight grounds, noted so low as 60o. This difference, which exceeds, altogether, the limits of probability, he would ascribe chiefly to the effect of a remarkable cold current that flows along the western coast of America, from the strait of Magellan to cape Parinna, and had, opposite to Lima, only the temperature of 61o. This singular current seems to be an exact counterpart to the famous gulph stream, which, on the other side of the continent, after having swept the bay of Mexico, shoots towards the northeast, till it loses itself in the Atlantick.

But the mean temperature of any place is materially affected by its elevation. A rapid interchange is incessantly maintained between the higher aud lower strata of the atmosphere. The heat, principally received at the surface, becomes thus almost uniformly diffused through the vetrical columns of air. When a warm portion of the fluid rises from below, an equal portion must descend; and this perpendicular communication, being confined to a space eight thousand times smaller than the range of the horizontal currents which connect the equator with the poles, may be considered as producing its full effect, and establishing a perfect equilibrium. The same absolute quantity of heat, therefore, exists at every height of the atmosphere. If the capacity of air were

not affected by its density, a uniform temperature would, in consequence, prevail through the whole vertical column. But, since the power of containing heat increases as the density of the fluid is diminished, the temperature of the higher regions of the atmosphere suffers a corresponding reduction. The temperature which obtains at any elevation, is, therefore, inversely proportional to the capacity for heat belonging to air of such density. From this principle, guided by experiment, and further adjusted by observation, we derive a very simple formula for expressing the diminution of temperature in the vertical ascent. The gradation is not uniform, as many have supposed; but decreases faster in the upper regions of the atmosphere. This inference is confirmed, by a close inspection of the best and most extensive observations. Under the equator, the decrement of heat, in mounting upwards, may be calculated, near the surface, at 324 feet, for each degree of Fahrenheit's scale; at 297 feet, when the height is 10,000 feet; and at 218 feet, for an elevation of 20,000 feet. M. Humboldt, reckoning the mean decrement at 344 feet, considers it as uniform to the height of 8,000 feet, and afterwards reduced to three fifths of that quantity beyond the elevation of 10,000 feet. This statement is quite anomalous; but it is connected with another strange opinion which he has advanced, in supposing that, above the height of three miles in the atmosphere, the same precise degree of cold prevails, in the whole extent, from the equator to the poles. The mean temperature of the city of Quito, at the height of 9,550 feet a bove the sea, may be computed at 53°; and that of Mexico, which has an elevation of 7,475 feet at 55°. Humboldt makes the former to be 58° 1-2, and the latter 62° 1-2; both of them obviously too great. The temperature of Mexico might, indeed, be somewhat raised above the

standard, from the circumstance of its lying in the midst of such a vast tract of high country, where the sun's heat is directly absorbed, and the communication between the upper and the under strata of the atmosphere is necessarily rendered circuitous.

But, when the observations of our ingenious traveller become more precise, they cease to be discordant with theory. In the torrid zone, the limit of perpetual congelation is very distinctly marked, not varying more than 100 yards under the equator, or 500 at the tropick of Cancer. This boundary, according to Humboldt, has an elevation of 15,700 feet at the equator, and 15,000 feet in the latitude of 20°; results which perfectly agree with the formula. We may remark, by the way, that the comparatively very narrow margin of the snow within the tropicks, causes the majestick Andes to want those glaciers, or icy belts, which, in Europe, bestow so much beauty and grandeur on the alpine scenery.

The settlers in New Spain distinguished the cultivated part of the country into three zones. 1. The tierras calientes, or warm grounds, which, never rising, 1,000 feet above the sea, have a heat of about 80°, and yield abundantly, sugar, indigo, cotton, and plantains or bannanas. 2. The tierras templadas, or temperate grounds, which, lying on the declivity of the great ridge, at an altitude from 4 to 5,000 feet, enjoy a mild, vernal temperature of 68° to 70°, that seldom varies ten degrees through the whole year. tierras frias, or cold grounds, having an elevation of 8,000 feet, and comprehending the high plains, or table land, such as that of Mexico, of which the temperature is generally under 63o, and never exceeds 75°.

3. The

In the torrid zone, the blue sky takes a deeper tint; the nights are resplendent; and the vault of heaven, exhibiting in succession the whole of

the constellations, appears studded with fixed stars, which shine like planets, with a clear and steady light. In the upper regions of the atmosphere, the attenuated air reflects only a dark azure. The cyanometer, which at Paris marked 16 degrees, indicated 23 near the shores of Cumana, and 46 on the heights of the Andes. So transparent is the air of those climates, that, in the mountains of Quito, one may distinguish, with the naked eye, the poncho, or white mantle of a person on horseback, at the distance of seventeen miles.

Mr. Humboldt laments that he had not an opportunity of trying, within the tropicks, the photometer with which professor Leslie has enriched our philosophical apparatus. We heartily join him in that feeling; but we regret still more that he had not employed the hygrometer, which the same philosopher has constructed from a nice view of the nature of evaporation; and which, combining accuracy of principle with facility of application, promises, when better understood and more generally diffused, to procure incalculable advantages to science and to the prac tice of the useful arts. The hair hygrometer of Saussure, the most delicate, perhaps, of all those formed with a hygroscopick substance, can only show, in any case, the relative attraction, as it is variously modified, of air, and of the material itself, for humidity. The instrument, on the summit of the Andes, was found to mark 46°, which quantity being reduced by correction to 32°, is conceived to denote most excessive dryness; a proof sufficiently striking, of the utter futility of the contrivance; for, at those vast heights, the air seems to be constantly charged with vapour; and drifting fogs moisten and refresh the languid vegetation of the paramos, or Alpine deserts. We will admit, that the capacities of air for heat and moisture are augmented together, by rarefac

tion. If an apartment in Quito were constantly heated up to the same degree as one at Lima, it would, no doubt, be much drier; but this disposition is at first counteracted by the cold which prevails in the su periour regions. The condition of the atmosphere in regard to humidity, depends on the opposite influence of two very different laws, which appear to perform an important part in the economy of nature. Where the antagonist forces balance each other, the greatest humidity exists. This is the proper region of the clouds, beyond which the sky is perpetually clear and serene. In the vicinity of the Andes, according to Humboldt, the large clouds are not seen to rise higher than 10 or 12,000 feet above the sea; but small white or fleecy clouds, which the inhabitants calls sheep, are often observed floating at a height of 25,000 feet. These mountains are moistened with perpetual dews. Hail and snow fall, in certain seasons of the year, at the elevation of 12,000 feet; but, at that of 10,000 feet, hail appears, accompanied with thunder. The high plain of Mexico is generally dry and parched, and in many parts covered with a saline efflorescence. Among the lower valleys, terrible storms of thunder, with torrents of rain, are frequent during the night. In New Spain, there are only two distinct seasons; the astacion de las aguas; or rainy season; which begins in June or July, and ends with September or October; and the estio, or dry season, which lasts during all the rest of the year. The annual fall of rain within the tropicks, may be stated at six feet; it amounts to eight feet at Guayaquil.

Uncultivated plains of amazing extent occur in South America. The Llanos, or savannahs, which stretch on a dead level for hundreds of miles southeast from the shores of the Orenocco, resemble the placid surface of the ocean. Covered with a thin layer of vegetable mould, and