We suffered greatly from the heat in crossing the Mesa de Calabozo. The temperature of the air augmented sensibly every time that the wind began to blow. The air was loaded with dust; and during these gusts the thermometer rose to 40 or 41 degrees. We went slowly forward, for it would have been dangerous to leave the mules that carried our instruments. Our guides advised us to fill our hats with the leaves of the rhopala, to diminish the action of the solar rays on the hair and the crown of the head. We found relief from this expedient, which was particularly agreeable, when we could procure the thick leaves of the pothos or some other similar plant.

It is impossible to cross these burning plains, without inquiring whether they have always been in the same state; or whether they have been stripped of their vegetation by some revolution of nature. The stratum of mould now found on them is in fact very thin. The natives believe that the palmares and the chaparales (the little groves of palm-trees and rhopala) were more frequent and more extensive before the arrival of the Spaniards. Since the Llanos have been inhabited and peopled with cattle become wild, the savannah is often set on fire, in order to ameliorate the pasturage. Groups of scattered trees are accidentally destroyed with the grasses. The plains were no doubt less bare in the fifteenth century, than they now are; yet the first Conquistadores, who came from Coro, described them then as savannahs, where nothing could be perceived but the sky and the turf, generally destitute of trees, and difficult to traverse on account of the reverberation of heat from the soil. Why does not the great forest of the Orinoco extend to the north, on the left bank of that river? Why does it not fill that vast space that reaches as far as the Cordillera of the coast, and which is fertilized by numerous rivers? These questions are connected with all that relates to the history of our planet. If, indulging in geological reveries, we suppose that the steppes of America, and the desert of Sahara, have been stripped of their vegetation by an irruption of the ocean, or that they formed originally the bottom of an inland sea, we may conceive that thousands of years have not sufficed for the trees and shrubs to advance from the borders of the forests, from the skirts of the plains either naked or covered with turf, toward the centre, and darken so vast a space with their shade. It is more difficult to explain the origin of bare savannahs, encircled by forests, than to recognize the causes that maintain forests and savannahs within their ancient limits, like continents and seas.

We found the most cordial hospitality at Calabozo, in the house of the superintendent of the royal plantations, Don Miguel Cousin. The town, situated between the banks of the Guarico and the Uritucu, contained at this period only five thousand inhabitants; but everything denoted increasing prosperity. The wealth of most of the inhabitants consists in herds, under the management of farmers, who are called hateros, from the word hato, which signifies in Spanish a house or farm placed in the midst of pastures. The scattered population of the Llanos being accumulated on certain points, principally around towns, Calabozo reckons already five villages or missions in its environs. It is computed, that 98,000 head of cattle wander in the pastures nearest to the town. It is very difficult to form an exact idea of the herds contained in the Llanos of Caracas, Barcelona, Cumana, and Spanish Guiana. M. Depons, who lived in the town of Caracas longer than I, and whose statistical statements are generally accurate, reckons in those vast plains, from the mouths of the Orinoco to the lake of Maracaybo, 1,200,000 oxen, 180,000 horses, and 90,000 mules. He estimates the produce of these herds at 5,000,000 francs; adding to the value of the exportation the price of the hides consumed in the country. There exist, it is believed, in the Pampas of Buenos Ayres, 12,000,000 cows, and 3,000,000 horses, without comprising in this enumeration the cattle that have no acknowledged proprietor.

I shall not hazard any general estimates, which from their nature are too uncertain; but shall only observe that, in the Llanos of Caracas, the proprietors of the great hatos are entirely ignorant of the number of the cattle they possess. They only know that of the young cattle, which are branded every year with a letter or mark peculiar to each herd. The richest proprietors mark as many as 14,000 head every year; and sell to the number of five or six thousand. According to official documents, the exportation of hides from the whole capitania-general of Caracas amounted annually to 174,000 skins of oxen, and 11,500 of goats. When we reflect, that these documents are taken from the books of the custom-houses, where no mention is made of the fraudulent dealings in hides, we are tempted to believe that the estimate of 1,200,000 oxen wandering in the Llanos, from the Rio Carony and the Guarapiche to the lake of Maracaybo, is much underrated. The port of La Guayra alone exported annually from 1789 to 1792, 70,000 or 80,000 hides, entered in the custom-house books, scarcely one-fifth of which was sent to Spain. The exportation from Buenos Ayres, at the end of the eighteenth century, was, according to Don Felix de Azara, 800,000 skins. The hides of Caracas are preferred in the Peninsula to those of Buenos Ayres; because the latter, on account of a longer passage, undergo a loss of twelve per cent in the tanning. The southern part of the savannahs, commonly called the Upper Plains (Llanos de arriba), is very productive in mules and oxen; but the pasturage being in general less good, these animals are obliged to be sent to other plains to be fattened before they are sold. The Llano de Monai, and all the Lower Plains (Llanos de abaxo), abound less in herds, but the pastures are so fertile, that they furnish meat of an excellent quality for the supply of the coast. The mules, which are not fit for labour before the fifth year, are purchased on the spot at the price of fourteen or eighteen piastres. The horses of the Llanos, descending from the fine Spanish breed, are not very large; they are generally of a uniform colour, brown bay, like most of the wild animals. Suffering alternately from drought and floods, tormented by the stings of insects and the bites of the large bats, they lead a sorry life. After having enjoyed for some months the care of man, their good qualities are developed. Here there are no sheep: we saw flocks only on the table-land of Quito.

The hatos of oxen have suffered considerably of late from troops of marauders, who roam over the steppes killing the animals merely to take their hides. This robbery has increased since the trade of the Lower Orinoco has become more flourishing. For half a century, the banks of that great river, from the mouth of the Apure as far as Angostura, were known only to the missionary-monks. The exportation of cattle took place from the ports of the northern coast only, namely from Cumana, Barcelona, Burburata, and Porto Cabello. This dependence on the coast is now much diminished. The southern part of the plains has established an internal communication with the Lower Orinoco; and this trade is the more brisk, as those who devote themselves to it easily escape the trammels of the prohibitory laws.

The greatest herds of cattle in the Llanos of Caracas are those of the hatos of Merecure, La Cruz, Belen, Alta Gracia, and Pavon. The Spanish cattle came from Coro and Tocuyo into the plains. History has preserved the name of the colonist who first conceived the idea of peopling these pasturages, inhabited only by deer, and a large species of cavy.* (* The thick-nosed tapir, or river cavy (Cavia capybara), called chiguire in those countries.) Christoval Rodriguez sent the first horned cattle into the Llanos, about the year 1548. He was an inhabitant of the town of Tocuyo, and had long resided in New Grenada.

When we hear of the innumerable quantity of oxen, horses, and mules, that are spread over the plains of America, we seem generally to forget that in civilized Europe, on lands of much less extent, there exist, in agricultural countries, quantities no less prodigious. France, according to M. Peuchet, feeds 6,000,000 large horned cattle, of which 3,500,000 are oxen employed in drawing the plough. In the Austrian monarchy, the number of oxen, cows, and calves, has been estimated at 13,400,000 head. Paris alone consumes annually 155,000 horned cattle. Germany receives 150,000 oxen yearly from Hungary. Domestic animals, collected in small herds, are considered by agricultural nations as a secondary object in the riches of the state. Accordingly they strike the imagination much less than those wandering droves of oxen and horses which alone fill the uncultivated tracts of the New World. Civilization and social order favour alike the progress of population, and the multiplication of animals useful to man.

We found at Calabozo, in the midst of the Llanos, an electrical machine with large plates, electrophori, batteries, electrometers; an apparatus nearly as complete as our first scientific men in Europe possess. All these articles had not been purchased in the United States; they were the work of a man who had never seen any instrument, who had no person to consult, and who was acquainted with the phenomena of electricity only by reading the treatise of De Lafond, and Franklin's Memoirs. Senor Carlos del Pozo, the name of this enlightened and ingenious man, had begun to make cylindrical electrical machines, by employing large glass jars, after having cut off the necks. It was only within a few years he had been able to procure, by way of Philadelphia, two plates, to construct a plate machine, and to obtain more considerable effects. It is easy to judge what difficulties Senor Pozo had to encounter, since the first works upon electricity had fallen into his hands, and that he had the courage to resolve to procure himself, by his own industry, all that he had seen described in his books. Till now he had enjoyed only the astonishment and admiration produced by his experiments on persons destitute of all information, and who had never quitted the solitude of the Llanos; our abode at Calabozo gave him a satisfaction altogether new. It may be supposed that he set some value on the opinions of two travellers who could compare his apparatus with those constructed in Europe. I had brought with me electrometers mounted with straw, pith-balls, and gold-leaf; also a small Leyden jar which could be charged by friction according to the method of Ingenhousz, and which served for my physiological experiments. Senor del Pozo could not contain his joy on seeing for the first time instruments which he had not made, yet which appeared to be copied from his own. We also showed him the effect of the contact of heterogeneous metals on the nerves of frogs. The name of Galvani and Volta had not previously been heard in those vast solitudes.

Next to his electrical apparatus, the work of the industry and intelligence of an inhabitant of the Llanos, nothing at Calabozo excited in us so great an interest as the gymnoti, which are animated electrical apparatuses. I was impatient, from the time of my arrival at Cumana, to procure electrical eels. We had been promised them often, but our hopes had always been disappointed. Money loses its value as you withdraw from the coast; and how is the imperturbable apathy of the ignorant people to be vanquished, when they are not excited by the desire of gain?

The Spaniards confound all electric fishes under the name of tembladores.* (* Literally "tremblers," or "producers of trembling.") There are some of these in the Caribbean Sea, on the coast of Cumana. The Guayquerie Indians, who are the most skilful and active fishermen in those parts, brought us a fish, which, they said, benumbed their hands. This fish ascends the little river Manzanares. It is a new species of ray, the lateral spots of which are scarcely visible, and which much resembles the torpedo. The torpedos, which are furnished with an electric organ externally visible, on account of the transparency of the skin, form a genus or subgenus different from the rays properly so called.* (* Cuvier, Regne Animal volume 2. The Mediterranean contains, according to M. Risso, four species of electrical torpedos, all formerly confounded under the name of Raia torpedo; these are Torpedo narke, T. unimaculata, T. galvanii, and T. marmorata. The torpedo of the Cape of Good Hope, the subject of the recent experiments of Mr. Todd, is, no doubt, a nondescript species.) The torpedo of Cumana was very lively, very energetic in its muscular movements, and yet the electric shocks it gave us were extremely feeble. They became stronger on galvanizing the animal by the contact of zinc and gold. Other tembladores, real gymnoti or electric eels, inhabit the Rio Colorado, the Guarapiche, and several little streams which traverse the Missions of the Chayma Indians. They abound also in the large rivers of America, the Orinoco, the Amazon, and the Meta; but the force of the currents and the depth of the water, prevent them from being caught by the Indians. They see these fish less frequently than they feel shocks from them when swimming or bathing in the river. In the Llanos, particularly in the environs of Calabozo, between the farms of Morichal and the Upper and Lower Missions, the basins of stagnant water and the confluents of the Orinoco (the Rio Guarico and the canos Rastro, Berito, and Paloma) are filled with electric eels. We at first wished to make our experiments in the house we inhabited at Calabozo; but the dread of the shocks caused by the gymnoti is so great, and so exaggerated among the common people, that during three days we could not obtain one, though they are easily caught, and we had promised the Indians two piastres for every strong and vigorous fish. This fear of the Indians is the more extraordinary, as they do not attempt to adopt precautions in which they profess to have great confidence. When interrogated on the effect of the tembladores, they never fail to tell the Whites, that they may be touched with impunity while you are chewing tobacco. This supposed influence of tobacco on animal electricity is as general on the continent of South America, as the belief among mariners of the effect of garlic and tallow on the magnetic needle.

Impatient of waiting, and having obtained very uncertain results from an electric eel which had been brought to us alive, but much enfeebled, we repaired to the Cano de Bera, to make our experiments in the open air, and at the edge of the water. We set off on the 19th of March, at a very early hour, for the village of Rastro; thence we were conducted by the Indians to a stream, which, in the time of drought, forms a basin of muddy water, surrounded by fine trees,* (* Amyris lateriflora, A. coriacea, Laurus pichurin. Myroxylon secundum, Malpighia reticulata.) the clusia, the amyris, and the mimosa with fragrant flowers. To catch the gymnoti with nets is very difficult, on account of the extreme agility of the fish, which bury themselves in the mud. We would not employ the barbasco, that is to say, the roots of the Piscidea erithyrna, the Jacquinia armillaris, and some species of phyllanthus, which thrown into the pool, intoxicate or benumb the eels. These methods have the effect of enfeebling the gymnoti. The Indians therefore told us that they would "fish with horses," (embarbascar con caballos.* (* Meaning to excite the fish by horses.)) We found it difficult to form an idea of this extraordinary manner of fishing; but we soon saw our guides return from the savannah, which they had been scouring for wild horses and mules. They brought about thirty with them, which they forced to enter the pool.

The extraordinary noise caused by the horses' hoofs, makes the fish issue from the mud, and excites them to the attack. These yellowish and livid eels, resembling large aquatic serpents, swim on the surface of the water, and crowd under the bellies of the horses and mules. A contest between animals of so different an organization presents a very striking spectacle. The Indians, provided with harpoons and long slender reeds, surround the pool closely; and some climb up the trees, the branches of which extend horizontally over the surface of the water. By their wild cries, and the length of their reeds, they prevent the horses from running away and reaching the bank of the pool. The eels, stunned by the noise, defend themselves by the repeated discharge of their electric batteries. For a long interval they seem likely to prove victorious. Several horses sink beneath the violence of the invisible strokes which they receive from all sides, in organs the most essential to life; and stunned by the force and frequency of the shocks, they disappear under the water. Others, panting, with mane erect, and haggard eyes expressing anguish and dismay, raise themselves, and endeavour to flee from the storm by which they are overtaken. They are driven back by the Indians into the middle of the water; but a small number succeed in eluding the active vigilance of the fishermen. These regain the shore, stumbling at every step, and stretch themselves on the sand, exhausted with fatigue, and with limbs benumbed by the electric shocks of the gymnoti.

In less than five minutes two of our horses were drowned. The eel being five feet long, and pressing itself against the belly of the horses, makes a discharge along the whole extent of its electric organ. It attacks at once the heart, the intestines, and the caeliac fold of the abdominal nerves. It is natural that the effect felt by the horses should be more powerful than that produced upon man by the touch of the same fish at only one of his extremities. The horses are probably not killed, but only stunned. They are drowned from the impossibility of rising amid the prolonged struggle between the other horses and the eels.

We had little doubt that the fishing would terminate by killing successively all the animals engaged; but by degrees the impetuosity of this unequal combat diminished, and the wearied gymnoti dispersed. They require a long rest, and abundant nourishment, to repair the galvanic force which they have lost.* (* The Indians assured us that when the horses are made to run two days successively into the same pool, none are killed the second day. See, on the fishing for gymnoti Views of Nature Bohn's edition page 18.) The mules and horses appear less frightened; their manes are no longer bristled, and their eyes express less dread. The gymnoti approach timidly the edge of the marsh, where they are taken by means of small harpoons fastened to long cords. When the cords are very dry the Indians feel no shock in raising the fish into the air. In a few minutes we had five large eels, most of which were but slightly wounded. Some others were taken, by the same means, towards evening.

The temperature of the waters in which the gymnoti habitually live, is from 26 to 27 degrees. Their electric force diminishes it is said, in colder waters; and it is remarkable that, in general, animals endowed with electromotive organs, the effects of which are sensible to man, are not found in the air, but in a fluid that is a conductor of electricity. The gymnotus is the largest of electrical fishes. I measured some that were from five feet to five feet three inches long; and the Indians assert that they have seen them still larger. We found that a fish of three feet ten inches long weighed twelve pounds. The transverse diameter of the body, without reckoning the anal fin, which is elongated in the form of a keel, was three inches and a half. The gymnoti of the Cano de Bera are of a fine olive-green. The under part of the head is yellow mingled with red. Two rows of small yellow spots are placed symmetrically along the back, from the head to the end of the tail. Every spot contains an excretory aperture. In consequence, the skin of the animal is constantly covered with a mucous matter, which, as Volta has proved, conducts electricity twenty or thirty times better than pure water. It is in general somewhat remarkable, that no electric fish yet discovered in the different parts of the world, is covered with scales.* (* We yet know with certainty only seven electric fishes; Torpedo narke, Risso, T. unimaculata, T. marmorata, T. galvanii, Silurus electricus, Tetraodon electricus, Gymnotus electricus. It appears uncertain whether the Trichiurus indicus has electrical properties or not. See Cuvier's Regne Animal volume 2. But the genus Torpedo, very different from that of the rays properly so called, has numerous species in the equatorial seas; and it is probable that there exist several gymnoti specifically different. The Indians mentioned to us a black and very powerful species, inhabiting the marshes of the Apure, which never attains a length of more than two feet, but which we were not able to procure. The raton of the Rio de la Magdalena, which I have described under the name of Gymnotus aequilabiatus (Observations de Zoologie volume 1) forms a particular sub-genus. This is a Carapa, not scaly, and without an electric organ. This organ is also entirely wanting in the Brazilian Carapo, and in all the rays which were carefully examined by Cuvier.)

The gymnoti, like our eels, are fond of swallowing and breathing air on the surface of the water; but we must not thence conclude that the fish would perish if it could not come up to breathe the air. The European eel will creep during the night upon the grass; but I have seen a very vigorous gymnotus that had sprung out of the water, die on the ground. M. Provencal and myself have proved by our researches on the respiration of fishes, that their humid bronchiae perform the double function of decomposing the atmospheric air, and of appropriating the oxygen contained in water. They do not suspend their respiration in the air; but they absorb the oxygen like a reptile furnished with lungs. It is known that carp may be fattened by being fed, out of the water, if their gills are wet from time to time with humid moss, to prevent them from becoming dry. Fish separate their gill-covers wider in oxygen gas than in water. Their temperature however, does not rise; and they live the same length of time in pure vital air, and in a mixture of ninety parts nitrogen and ten oxygen. We found that tench placed under inverted jars filled with air, absorb half a cubic centimetre of oxygen in an hour. This action takes place in the gills only; for fishes on which a collar of cork has been fastened, and leaving their head out of the jar filled with air, do not act upon the oxygen by the rest of their body.

The swimming-bladder of the gymnotus is two feet five inches long in a fish of three feet ten inches.* (* Cuvier has shown that in the Gymnotus electricus there exists, besides the large swimming-bladder, another situated before it, and much smaller. It looks like the bifurcated swimming-bladder in the Gymnotus aequilabiatus.) It is separated by a mass of fat from the external skin; and rests upon the electric organs, which occupy more than two-thirds of the animal's body. The same vessels which penetrate between the plates or leaves of these organs, and which cover them with blood when they are cut transversely, also send out numerous branches to the exterior surface of the air-bladder. I found in a hundred parts of the air of the swimming-bladder four of oxygen and ninety-six of nitrogen. The medullary substance of the brain displays but a feeble analogy with the albuminous and gelatinous matter of the electric organs. But these two substances have in common the great quantity of arterial blood which they receive, and which is deoxidated in them. We may again remark, on this occasion, that an extreme activity in the functions of the brain causes the blood to flow more abundantly towards the head, as the energy of the movement of the muscles accelerates the deoxidation of the arterial blood. What a contrast between the multitude and the diameter of the blood-vessels of the gymnotus, and the small space occupied by its muscular system! This contrast reminds the observer, that three functions of animal life, which appear in other respects sufficiently distinct—the functions of the brain, those of the electrical organ, and those of the muscles, all require the afflux and concourse of arterial or oxygenated blood.

It would be temerity to expose ourselves to the first shocks of a very large and strongly irritated gymnotus. If by chance a stroke be received before the fish is wounded or wearied by long pursuit, the pain and numbness are so violent that it is impossible to describe the nature of the feeling they excite. I do not remember having ever received from the discharge of a large Leyden jar, a more dreadful shock than that which I experienced by imprudently placing both my feet on a gymnotus just taken out of the water. I was affected during the rest of the day with a violent pain in the knees, and in almost every joint. To be aware of the difference that exists between the sensation produced by the Voltaic battery and an electric fish, the latter should be touched when they are in a state of extreme weakness. The gymnoti and the torpedos then cause a twitching of the muscles, which is propagated from the part that rests on the electric organs, as far as the elbow. We seem to feel, at every stroke, an internal vibration, which lasts two or three seconds, and is followed by a painful numbness. Accordingly, the Tamanac Indians call the gymnotus, in their expressive language, arimna, which means something that deprives of motion.

The sensation caused by the feeble shocks of an electric eel appeared to me analogous to that painful twitching with which I have been seized at each contact of two heterogeneous metals applied to wounds which I had made on my back by means of cantharides. This difference of sensation between the effects of electric fishes and those of a Voltaic battery or a Leyden jar feebly charged has struck every observer; there is, however, nothing in this contrary to the supposition of the identity of electricity and the galvanic action of fishes. The electricity may be the same; but its effects will be variously modified by the disposition of the electrical apparatus, by the intensity of the fluid, by the rapidity of the current, and by the particular mode of action.

In Dutch Guiana, at Demerara for instance, electric eels were formerly employed to cure paralytic affections. At a time when the physicians of Europe had great confidence in the effects of electricity, a surgeon of Essequibo, named Van der Lott, published in Holland a treatise on the medical properties of the gymnotus. These electric remedies are practised among the savages of America, as they were among the Greeks. We are told by Scribonius Largus, Galen, and Dioscorides, that torpedos cure the headache and the gout. I did not hear of this mode of treatment in the Spanish colonies which I visited; and I can assert that, after having made experiments during four hours successively with gymnoti, M. Bonpland and myself felt, till the next day, a debility in the muscles, a pain in the joints, and a general uneasiness, the effect of a strong irritation of the nervous system.

The gymnotus is neither a charged conductor, nor a battery, nor an electromotive apparatus, the shock of which is received every time they are touched with one hand, or when both hands are applied to form a conducting circle between the opposite poles. The electric action of the fish depends entirely on its will; because it does not keep its electric organs always charged, or whether by the secretion of some fluid, or by any other means alike mysterious to us, it be capable of directing the action of its organs to an external object. We often tried, both insulated and otherwise, to touch the fish, without feeling the least shock. When M. Bonpland held it by the head, or by the middle of the body, while I held it by the tail, and, standing on the moist ground, did not take each other's hand, one of us received shocks, which the other did not feel. It depends upon the gymnotus to direct its action towards the point where it finds itself most strongly irritated. The discharge is then made at one point only, and not at the neighbouring points. If two persons touch the belly of the fish with their fingers, at an inch distance, and press it simultaneously, sometimes one, sometimes the other, will receive the shock. In the same manner, when one insulated person holds the tail of a vigorous gymnotus, and another pinches the gills or pectoral fin, it is often the first only by whom the shock is received. It did not appear to us that these differences could be attributed to the dryness or moisture of our hands, or to their unequal conducting power. The gymnotus seemed to direct its strokes sometimes from the whole surface of its body, sometimes from one point only. This effect indicates less a partial discharge of the organ composed of an innumerable quantity of layers, than the faculty which the animal possesses, (perhaps by the instantaneous secretion of a fluid spread through the cellular membrane,) of establishing the communication between its organs and the skin only, in a very limited space.

Nothing proves more strongly the faculty, which the gymnotus possesses, of darting and directing its stroke at will, than the observations made at Philadelphia and Stockholm,* on gymnoti rendered extremely tame. (* By MM. Williamson and Fahlberg. The following account is given by the latter gentleman. "The gymnotus sent from Surinam to M. Norderling, at Stockholm, lived more than four months in a state of perfect health. It was twenty-seven inches long; and the shocks it gave were so violent, especially in the open air, that I found scarcely any means of protecting myself by non-conductors, in transporting the fish from one place to another. Its stomach being very small, it ate little at a time, but fed often. It approached living fish, first sending them from afar a shock, the energy of which was proportionate to the size of the prey. The gymnotus seldom failed in its aim; one single stroke was almost always sufficient to overcome the resistance which the strata of water, more or less thick according to the distance, opposed to the electrical current. When very much pressed by hunger, it sometimes directed the shocks against the person who daily brought its food of boiled meat. Persons afflicted with rheumatism came to touch it in hopes of being cured. They took it at once by the neck and tail the shocks were in this case stronger than when touched with one hand only. It almost entirely lost its electrical power a short time before its death.") When they had been made to fast a long time, they killed small fishes put into the tub. They acted from a distance; that is to say, their electrical shock passed through a very thick stratum of water. We need not be surprised that what was observed in Sweden, on a single gymnotus only, we could not perceive in a great number of individuals in their native country. The electric action of animals being a vital action, and subject to their will, it does not depend solely on their state of health and vigour. A gymnotus that has been kept a long time in captivity, accustoms itself to the imprisonment to which it is reduced; it resumes by degrees the same habits in the tub, which it had in the rivers and marshes. An electrical eel was brought to me at Calabozo: it had been taken in a net, and consequently having no wound. It ate meat, and terribly frightened the little tortoises and frogs which, not aware of their danger, placed themselves on its back. The frogs did not receive the stroke till the moment when they touched the body of the gymnotus. When they recovered, they leaped out of the tub; and when replaced near the fish, they were frightened at the mere sight of it. We then observed nothing that indicated an action at a distance; but our gymnotus, recently taken, was not yet sufficiently tame to attack and devour frogs. On approaching the finger, or the metallic points, very close to the electric organs, no shock was felt. Perhaps the animal did not perceive the proximity of a foreign body; or, if it did, we must suppose that in the commencement of its captivity, timidity prevented it from darting forth its energetic strokes except when strongly irritated by an immediate contact. The gymnotus being immersed in water, I placed my hand, both armed and unarmed with metal, within a very small distance from the electric organs; yet the strata of water transmitted no shock, while M. Bonpland irritated the animal strongly by an immediate contact, and received some very violent shocks. Had we placed a very delicate electroscope in the contiguous strata of water, it might possibly have been influenced at the moment when the gymnotus seemed to direct its stroke elsewhere. Prepared frogs, placed immediately on the body of a torpedo, experience, according to Galvani, a strong contraction at every discharge of the fish.

The electrical organ of the gymnoti acts only under the immediate influence of the brain and the heart. On cutting a very vigorous fish through the middle of the body, the fore part alone gave shocks. These are equally strong in whatever part of the body the fish is touched; it is most disposed, however, to emit them when the pectoral fin, the electrical organ, the lips, the eyes, or the gills, are pinched. Sometimes the animal struggles violently with a person holding it by the tail, without communicating the least shock. Nor did I feel any when I made a slight incision near the pectoral fin of the fish, and galvanized the wound by the contact of two pieces of zinc and silver. The gymnotus bent itself convulsively, and raised its head out of the water, as if terrified by a sensation altogether new; but I felt no vibration in the hands which held the two metals. The most violent muscular movements are not always accompanied by electric discharges.

The action of the fish on the human organs is transmitted and intercepted by the same bodies that transmit and intercept the electrical current of a conductor charged by a Leyden jar, or Voltaic battery. Some anomalies, which we thought we observed, are easily explained, when we recollect that even metals (as is proved from their ignition when exposed to the action of the battery) present a slight obstacle to the passage of electricity; and that a bad conductor annihilates the effect, on our organs, of a feeble electric charge, whilst it transmits to us the effect of a very strong one. The repulsive force which zinc and silver exercise together being far superior to that of gold and silver, I have found that when a frog, prepared and armed with silver, is galvanized under water, the conducting arc of zinc produces contraction as soon as one of its extremities approaches the muscles within three lines distance; while an arc of gold does not excite the organs, when the stratum of water between the gold and the muscles is more than half a line thick. In the same manner, by employing a conducting arc composed of two pieces of zinc and silver soldered together endways; and resting, as before, one of the extremities of the metallic circuit on the femoral nerve, it is necessary, in order to produce contractions, to bring the other extremity of the conductor nearer and nearer to the muscles, in proportion as the irritability of the organs diminishes. Toward the end of the experiment the slightest stratum of water prevents the passage of the electrical current, and it is only by the immediate contact of the arc with the muscles, that the contractions take place. These effects are, however, dependent on three variable circumstances; the energy of the electromotive apparatus, the conductibility of the medium, and the irritability of the organs which receive the impressions: it is because experiments have not been sufficiently multiplied with a view to these three variable elements, that, in the action of electric eels and torpedos, accidental circumstances have been taken for absolute conditions, without which the electric shocks are not felt.

In wounded gymnoti, which give feeble but very equal shocks, these shocks appeared to us constantly stronger on touching the body of the fish with a hand armed with metal, than with the naked hand. They are stronger also, when, instead of touching the fish with one hand, naked, or armed with metal, we press it at once with both hands, either naked or armed. These differences become sensible only when one has gymnoti enough at disposal to be able to choose the weakest; and when the extreme equality of the electric discharges admits of distinguishing between the sensations felt alternately by the hand naked or armed with a metal, by one or both hands naked, and by one or both hands armed with metal. It is also in the case only of small shocks, feeble and uniform, that they are more sensible on touching the gymnotus with one hand (without forming a chain) with zinc, than with copper or iron.

Resinous substances, glass, very dry wood, horn, and even bones, which are generally believed to be good conductors, prevent the action of the gymnoti from being transmitted to man. I was surprised at not feeling the least shock on pressing wet sticks of sealing-wax against the organs of the fish, while the same animal gave me the most violent strokes, when excited by means of a metallic rod. M. Bonpland received shocks, when carrying a gymnotus on two cords of the fibres of the palm-tree, which appeared to us extremely dry. A strong discharge makes its way through very imperfect conductors. Perhaps also the obstacle which the conductor presents renders the discharge more painful. I touched the gymnotus with a wet pot of brown clay, without effect; yet I received violent shocks when I carried the gymnotus in the same pot, because the contact was greater.

When two persons, insulated or otherwise, hold each other's hands, and only one of these persons touches the fish with the hand, either naked or armed with metal, the shock is most commonly felt by both at once. However, it sometimes happens that, in the most severe shocks, the person who comes into immediate contact with the fish alone feels them. When the gymnotus is exhausted, or in a very reduced state of excitability, and will no longer emit strokes on being irritated with one hand, the shocks are felt in a very vivid manner, on forming the chain, and employing both hands. Even then, however, the electric shock takes place only at the will of the animal. Two persons, one of whom holds the tail, and the other the head, cannot, by joining hands and forming a chain, force the gymnotus to dart his stroke.

Though employing the most delicate electrometers in various ways, insulating them on a plate of glass, and receiving very strong shocks which passed through the electrometer, I could never discover any phenomenon of attraction or repulsion. The same observation was made by M. Fahlberg at Stockholm. That philosopher, however, has seen an electric spark, as Walsh and Ingenhousz had before him, in London, by placing the gymnotus in the air, and interrupting the conducting chain by two gold leaves pasted upon glass, and a line distant from each other. No person, on the contrary, has ever perceived a spark issue from the body of the fish itself. We irritated it for a long time during the night, at Calabozo, in perfect darkness, without observing any luminous appearance. Having placed four gymnoti, of unequal strength, in such a manner as to receive the shocks of the most vigorous fish by contact, that is to say, by touching only one of the other fishes, I did not observe that these last were agitated at the moment when the current passed their bodies. Perhaps the current did not penetrate below the humid surface of the skin. We will not, however, conclude from this, that the gymnoti are insensible to electricity; and that they cannot fight with each other at the bottom of the pools. Their nervous system must be subject to the same agents as the nerves of other animals. I have indeed seen, that, on laying open their nerves, they undergo muscular contractions at the mere contact of two opposite metals; and M. Fahlberg, of Stockholm, found that his gymnotus was convulsively agitated when placed in a copper vessel, and feeble discharges from a Leyden jar passed through its skin.

After the experiments I had made on gymnoti, it became highly interesting to me, on my return to Europe, to ascertain with precision the various circumstances in which another electric fish, the torpedo of our seas, gives or does not give shocks. Though this fish had been examined by numerous men of science, I found all that had been published on its electrical effects extremely vague. It has been very arbitrarily supposed, that this fish acts like a Leyden jar, which may be discharged at will, by touching it with both hands; and this supposition appears to have led into error observers who have devoted themselves to researches of this kind. M. Gay-Lussac and myself, during our journey to Italy, made a great number of experiments on torpedos taken in the gulf of Naples. These experiments furnish many results somewhat different from those I collected on the gymnoti. It is probable that the cause of these anomalies is owing rather to the inequality of electric power in the two fishes, than to the different disposition of their organs.

Though the power of the torpedo cannot be compared with that of the gymnotus, it is sufficient to cause very painful sensations. A person accustomed to electric shocks can with difficulty hold in his hands a torpedo of twelve or fourteen inches, and in possession of all its vigour. When the torpedo gives only very feeble strokes under water, they become more sensible if the animal be raised above the surface. I have often observed the same phenomenon in experimenting on frogs.

The torpedo moves the pectoral fins convulsively every time it emits a stroke; and this stroke is more or less painful, according as the immediate contact takes place by a greater or less surface. We observed that the gymnotus gives the strongest shocks without making any movement with the eyes, head, or fins.* (* The anal fin of the gymnoti only has a sensible motion when these fishes are excited under the belly, where the electric organ is placed.) Is this difference caused by the position of the electric organ, which is not double in the gymnoti? or does the movement of the pectoral fins of the torpedo directly prove that the fish restores the electrical equilibrium by its own skin, discharges itself by its own body, and that we generally feel only the effect of a lateral shock?

We cannot discharge at will either a torpedo or a gymnotus, as we discharge at will a Leyden jar or a Voltaic battery. A shock is not always felt, even on touching the electric fish with both hands. We must irritate it to make it give the shock. This action in the torpedos, as well as in the gymnoti, is a vital action; it depends on the will only of the animal, which perhaps does not always keep its electric organs charged, or does not always employ the action of its nerves to establish the chain between the positive and negative poles. It is certain that the torpedo gives a long series of shocks with astonishing celerity; whether it is that the plates or laminae of its organs are not wholly exhausted, or that the fish recharges them instantaneously.

The electric stroke is felt, when the animal is disposed to give it, whether we touch with a single finger only one of the surfaces of the organs, or apply both hands to the two surfaces, the superior and inferior, at once. In either case it is altogether indifferent whether the person who touches the fish with one finger or both hands be insulated or not. All that has been said on the necessity of a communication with the damp ground to establish a circuit, is founded on inaccurate observations.

M. Gay-Lussac made the important observation that when an insulated person touches the torpedo with one finger, it is indispensible that the contact be direct. The fish may with impunity be touched with a key, or any other metallic instrument; no shock is felt when a conducting or non-conducting body is interposed between the finger and the electrical organ of the torpedo. This circumstance proves a great difference between the torpedo and the gymnotus, the latter giving his strokes through an iron rod several feet long.

When the torpedo is placed on a metallic plate of very little thickness, so that the plate touches the inferior surface of the organs, the hand that supports the plate never feels any shock, though another insulated person may excite the animal, and the convulsive movement of the pectoral fins may denote the strongest and most reiterated discharges.

If, on the contrary, a person support the torpedo placed upon a metallic plate, with the left hand, as in the foregoing experiment, and the same person touch the superior surface of the electrical organ with the right hand, a strong shock is then felt in both arms. The sensation is the same when the fish is placed between two metallic plates, the edges of which do not touch, and the person applies both hands at once to these plates. The interposition of one metallic plate prevents the communication if that plate be touched with one hand only, while the interposition of two metallic plates does not prevent the shock when both hands are applied. In the latter case it cannot be doubted that the circulation of the fluid is established by the two arms.

If, in this situation of the fish between two plates, there exist any immediate communication between the edges of these two plates, no shock takes place. The chain between the two surfaces of the electric organ is then formed by the plates, and the new communication, established by the contact of the two hands with the two plates, remains without effect. We carried the torpedo with impunity between two plates of metal, and felt the strokes it gave only at the instant when they ceased to touch each other at the edges.

Nothing in the torpedo or in the gymnotus indicates that the animal modifies the electrical state of the bodies by which it is surrounded. The most delicate electrometer is no way affected in whatever manner it is employed, whether bringing it near the organs or insulating the fish, covering it with a metallic plate, and causing the plate to communicate by a conducting wire with the condenser of Volta. We were at great pains to vary the experiments by which we sought to render the electrical tension of the torpedo sensible; but they were constantly without effect, and perfectly confirmed what M. Bonpland and myself had observed respecting the gymnoti, during our abode in South America.

Electrical fishes, when very vigorous, act with equal energy under water and in the air. This observation led us to examine the conducting property of water; and we found that, when several persons form the chain between the superior and inferior surface of the organs of the torpedo, the shock is felt only when these persons join hands. The action is not intercepted if two persons, who support the torpedo with their right hands, instead of taking one another by the left hand, plunge each a metallic point into a drop of water placed on an insulating substance. On substituting flame for the drop of water, the communication is interrupted, and is only re-established, as in the gymnotus, when the two points immediately touch each other in the interior of the flame.

We are, doubtless, very far from having discovered all the secrets of the electrical action of fishes which is modified by the influence of the brain and the nerves; but the experiments we have just described are sufficient to prove that these fishes act by a concealed electricity, and by electromotive organs of a peculiar construction, which are recharged with extreme rapidity. Volta admits that the discharges of the opposite electricities in the torpedos and the gymnoti are made by their own skin, and that when we touch them with one hand only, or by means of a metallic point, we feel the effect of a lateral shock, the electrical current not being directed solely the shortest way. When a Leyden jar is placed on a wet woollen cloth (which is a bad conductor), and the jar is discharged in such a manner that the cloth makes part of the chain, prepared frogs, placed at different distances, indicate by their contractions that the current spreads itself over the whole cloth in a thousand different ways. According to this analogy, the most violent shock given by the gymnotus at a distance would be but a feeble part of the stroke which re-establishes the equilibrium in the interior of the fish.* (* The heterogeneous poles of the double electrical organs must exist in each organ. Mr. Todd has recently proved, by experiments made on torpedos at the Cape of Good Hope, that the animal continues to give violent shocks when one of these organs is extirpated. On the contrary, all electrical action is stopped (and this point, as elucidated by Galvani, is of the greatest importance) if injury be inflicted on the brain, or if the nerves which supply the plates of the electrical organs be divided. In the latter case, the nerves being cut, and the brain left untouched, the torpedo continues to live, and perform every muscular movement. A fish, exhausted by too numerous electrical discharges, suffered much more than another fish deprived, by dividing the nerves, of any communication between the brain and the electromotive apparatus. Philosophical Transactions 1816.) As the gymnotus directs its stroke wherever it pleases, it must also be admitted that the discharge is not made by the whole skin at once, but that the animal, excited perhaps by the motion of a fluid poured into one part of the cellular membrane, establishes at will the communication between its organs and some particular part of the skin. It may be conceived that a lateral stroke, out of the direct current, must become imperceptible under the two conditions of a very weak discharge, or a very great obstacle presented by the nature and length of the conductor. Notwithstanding these considerations, it appears to me very surprising that shocks of the torpedo, strong in appearance, are not propagated to the hand when a very thin plate of metal is interposed between it and the fish.

Schilling declared that the gymnotus approached the magnet involuntarily. We tried in a thousand ways this supposed influence of the magnet on the electrical organs, without having ever observed any sensible effect. The fish no more approached the magnet, than a bar of iron not magnetic. Iron-filings, thrown on its back, remained motionless.

The gymnoti, which are objects of curiosity and of the deepest interest to the philosophers of Europe, are at once dreaded and detested by the natives. They furnish, indeed, in their muscular flesh, pretty good aliment; but the electric organ fills the greater part of their body, and this organ is slimy, and disagreeable to the taste; it is accordingly separated with care from the rest of the eel. The presence of gymnoti is also considered as the principal cause of the want of fish in the ponds and pools of the Llanos. They, however, kill many more than they devour: and the Indians told us, that when young alligators and gymnoti are caught at the same time in very strong nets, the latter never show the slightest trace of a wound, because they disable the young alligators before they are attacked by them. All the inhabitants of the waters dread the society of the gymnoti. Lizards, tortoises, and frogs, seek pools where they are secure from the electric action. It became necessary to change the direction of a road near Uritucu, because the electric eels were so numerous in one river, that they every year killed a great number of mules, as they forded the water with their burdens.

Though in the present state of our knowledge we may flatter ourselves with having thrown some light on the extraordinary effects of electric fishes, yet a vast number of physical and physiological researches still remain to be made. The brilliant results which chemistry has obtained by means of the Voltaic battery, have occupied all observers, and turned attention for some time from the examinations of the phenomena of vitality. Let us hope that these phenomena, the most awful and the most mysterious of all, will in their turn occupy the earnest attention of natural philosophers. This hope will be easily realized if they succeed in procuring anew living gymnoti in some one of the great capitals of Europe. The discoveries that will be made on the electromotive apparatus of these fish, much more energetic, and more easy of preservation, than the torpedos,* will extend to all the phenomena of muscular motion subject to volition. (* In order to investigate the phenomena of the living electromotive apparatus in its greatest simplicity, and not to mistake for general conditions circumstances which depend on the degree of energy of the electric organs, it is necessary to perform the experiments on those electrical fishes most easily tamed. If the gymnoti were not known, we might suppose, from the observations made on torpedos, that fishes cannot give their shocks from a distance through very thick strata of water, or through a bar of iron, without forming a circuit. Mr. Williamson has felt strong shocks when he held only one hand in the water, and this hand, without touching the gymnotus, was placed between it and the small fish towards which the stroke was directed from ten or fifteen inches distance. Philosophical Transactions volume 65 pages 99 and 108. When the gymnotus was enfeebled by bad health, the lateral shock was imperceptible; and in order to feel the shock, it was necessary to form a chain, and touch the fish with both hands at once. Cavendish, in his ingenious experiments on an artificial torpedo, had well remarked these differences, depending on the greater or less energy of the charge. Philosophical Transactions 1776 page 212.) It will perhaps be found that, in most animals, every contraction of the muscular fibre is preceded by a discharge from the nerve into the muscle; and that the mere simple contact of heterogeneous substances is a source of movement and of life in all organized beings. Did an ingenious and lively people, the Arabians, guess from remote antiquity, that the same force which inflames the vault of Heaven in storms, is the living and invisible weapon of inhabitants of the waters? It is said, that the electric fish of the Nile bears a name in Egypt, that signifies thunder.* (* It appears, however, that a distinction is to be made between rahd, thunder, and rahadh, the electrical fish; and that this latter word means simply that which causes trembling.)

We left the town of Calabozo on the 24th of March, highly satisfied with our stay, and the experiments we had made on an object so worthy of the attention of physiologists. I had besides obtained some good observations of the stars; and discovered with surprise, that the errors of maps amounted here also to a quarter of a degree of latitude. No person had taken an observation before me on this spot; and geographers, magnifying as usual the distance from the coast to the islands, have carried back beyond measure all the localities towards the south.

As we advanced into the southern part of the Llanos, we found the ground more dusty, more destitute of herbage, and more cracked by the effect of long drought. The palm-trees disappeared by degrees. The thermometer kept, from eleven in the morning till sunset, at 34 or 35 degrees. The calmer the air appeared at eight or ten feet high, the more we were enveloped in those whirlwinds of dust, caused by the little currents of air that sweep the ground. About four o'clock in the afternoon, we found a young Indian girl stretched upon the savannah. She was almost in a state of nudity, and appeared to be about twelve or thirteen years of age. Exhausted with fatigue and thirst, her eyes, nostrils, and mouth filled with dust, she breathed with a rattling in her throat, and was unable to answer our questions. A pitcher, overturned, and half filled with sand, was lying at her side. Happily one of our mules was laden with water; and we roused the girl from her lethargic state by bathing her face, and forcing her to drink a few drops of wine. She was at first alarmed on seeing herself surrounded by so many persons; but by degrees she took courage, and conversed with our guides. She judged, from the position of the sun, that she must have remained during several hours in that state of lethargy. We could not prevail on her to mount one of our beasts of burden, and she would not return to Uritucu. She had been in service at a neighbouring farm; and she had been discharged, because at the end of a long sickness she was less able to work than before. Our menaces and prayers were alike fruitless; insensible to suffering, like the rest of her race, she persisted in her resolution of going to one of the Indian Missions near the city of Calabozo. We removed the sand from her pitcher, and filled it with water. She resumed her way along the steppe, before we had remounted our horses, and was soon separated from us by a cloud of dust. During the night we forded the Rio Uritucu, which abounds with a breed of crocodiles remarkable for their ferocity. We were advised to prevent our dogs from going to drink in the rivers, for it often happens that the crocodiles of Uritucu come out of the water, and pursue dogs upon the shore. This intrepidity is so much the more striking, as at eight leagues distance, the crocodiles of the Rio Tisnao are extremely timid, and little dangerous. The manners of animals vary in the same species according to local circumstances difficult to be determined. We were shown a hut, or rather a kind of shed, in which our host of Calabozo, Don Miguel Cousin, had witnessed a very extraordinary scene. Sleeping with one of his friends on a bench or couch covered with leather, Don Miguel was awakened early in the morning by a violent shaking and a horrible noise. Clods of earth were thrown into the middle of the hut. Presently a young crocodile two or three feet long issued from under the bed, darted at a dog which lay on the threshold of the door, and, missing him in the impetuosity of his spring, ran towards the beach to gain the river. On examining the spot where the barbacoa, or couch, was placed, the cause of this strange adventure was easily discovered. The ground was disturbed to a considerable depth. It was dried mud, which had covered the crocodile in that state of lethargy, or summer-sleep, in which many of the species lie during the absence of the rains in the Llanos. The noise of men and horses, perhaps the smell of the dog, had aroused the crocodile. The hut being built at the edge of the pool, and inundated during part of the year, the crocodile had no doubt entered, at the time of the inundation of the savannahs, by the same opening at which it was seen to go out. The Indians often find enormous boas, which they call uji, or water-serpents,* in the same lethargic state. (* Culebra de agua, named by the common people traga-venado, the swallower of stags. The word uji belongs to the Tamanac language.) To reanimate them, they must be irritated, or wetted with water. Boas are killed, and immersed in the streams, to obtain, by means of putrefaction, the tendinous parts of the dorsal muscles, of which excellent guitar-strings are made at Calabozo, preferable to those furnished by the intestines of the alouate monkeys.

The drought and heat of the Llanos act like cold upon animals and plants. Beyond the tropics the trees lose their leaves in a very dry air. Reptiles, particularly crocodiles and boas, having very indolent habits, leave with reluctance the basins in which they have found water at the period of great inundations. In proportion as the pools become dry, these animals penetrate into the mud, to seek that degree of humidity which gives flexibility to their skin and integuments. In this state of repose they are seized with stupefaction; but possibly they preserve a communication with the external air; and, however little that communication may be, it possibly suffices to keep up the respiration of an animal of the saurian family, provided with enormous pulmonary sacs, exerting no muscular motion, and in which almost all the vital functions are suspended. It is probable that the mean temperature of the dried mud, exposed to the solar rays, is more than 40 degrees. When the north of Egypt, where the coolest month does not fall below 13.4 degrees, was inhabited by crocodiles, they were often found torpid with cold. They were subject to a winter-sleep, like the European frog, lizard, sand-martin, and marmot. If the hibernal lethargy be observed, both in cold-blooded and in hot-blooded animals, we shall be less surprised to learn, that these two classes furnish alike examples of a summer-sleep. In the same manner as the crocodiles of South America, the tanrecs, or Madagascar hedgehogs, in the midst of the torrid zone, pass three months of the year in lethargy.

On the 25th of March we traversed the smoothest part of the steppes of Caracas, the Mesa de Pavones. It is entirely destitute of the corypha and moriche palm-trees. As far as the eye can reach, not a single object fifteen inches high can be discovered. The air was clear, and the sky of a very deep blue; but the horizon reflected a livid and yellowish light, caused no doubt by the quantity of sand suspended in the atmosphere. We met some large herds of cattle, and with them flocks of birds of a black colour with an olive shade. They are of the genus Crotophaga,* and follow the cattle. (* The Spanish colonists call the Crotophaga ani, zamurito (little carrion vulture—Vultur aura minuta), or garapatero, the eater of garaparas, insects of the Acarus family.) We had often seen them perched on the backs of cows, seeking for gadflies and other insects. Like many birds of these desert places, they fear so little the approach of man, that children often catch them in their hands. In the valleys of Aragua, where they are very common, we have seen them perch upon the hammocks on which we were reposing, in open day.

We discover, between Calabozo, Uritucu, and the Mesa de Pavones, wherever there are excavations of some feet deep, the geological constitution of the Llanos. A formation of red sandstone (ancient conglomerate) covers an extent of several thousand square leagues. We shall find it again in the vast plains of the Amazon, on the eastern boundary of the province of Jaen de Bracamoros. This prodigious extension of red sandstone in the low grounds stretching along the east of the Andes, is one of the most striking phenomena I observed during my examination of rocks in the equinoctial regions.

The red sandstone of the Llanos of Caracas lies in a concave position, between the primitive mountains of the shore and of Parime. On the north it is backed by the transition-slates,* (* At Malpaso and Piedras Azules.) and on the south it rests immediately on the granites of the Orinoco. We observed in it rounded fragments of quartz (kieselschiefer), and Lydian stone, cemented by an olive-brown ferruginous clay. The cement is sometimes of so bright a red that the people of the country take it for cinnabar. We met a Capuchin monk at Calabozo, who was in vain attempting to extract mercury from this red sandstone. In the Mesa de Paja this rock contains strata of another quartzose sandstone, very fine-grained; more to the south it contains masses of brown iron, and fragments of petrified trees of the monocotyledonous family, but we did not see in it any shells. The red sandstone, called by the Llaneros, the stone of the reefs (piedra de arrecifes), is everywhere covered with a stratum of clay. This clay, dried and hardened in the sun, splits into separate prismatic pieces with five or six sides. Does it belong to the trap-formation of Parapara? It becomes thicker, and mixed with sand, as we approach the Rio Apure; for near Calabozo it is one toise thick, near the mission of Guayaval five toises, which may lead to the belief that the strata of red sandstone dips towards the south. We gathered in the Mesa de Pavones little nodules of blue iron-ore disseminated in the clay.

A dense whitish-gray limestone, with a smooth fracture, somewhat analogous to that of Caripe, and consequently to that of Jura, lies on the red sandstone between Tisnao and Calabozo.* (* Does this formation of secondary limestone of the Llanos contain galena? It has been found in strata of black marl, at Barbacoa, between Truxillo and Barquesimeto, north-west of the Llanos.) In several other places, for instance in the Mesa de San Diego, and between Ortiz and the Mesa de Paja,* (* Also near Cachipe and San Joacquim, in the Llanos of Barcelona.) we find above the limestone lamellar gypsum alternating with strata of marl. Considerable quantities of this gypsum are sent to the city of Caracas,* which is situated amidst primitive mountains. (* This trade is carried on at Parapara. A load of eight arrobas sells at Caracas for twenty-four piastres.)

This gypsum generally forms only small beds, and is mixed with a great deal of fibrous gypsum. Is it of the same formation as that of Guire, on the coast of Paria, which contains sulphur? or do the masses of this latter substance, found in the valley of Buen Pastor and on the banks of the Orinoco, belong, with the argillaceous gypsum of the Llanos, to a secondary formation much more recent.

These questions are very interesting in the study of the relative antiquity of rocks, which is the principal basis of geology. I know not of any salt-deposits in the Llanos. Horned cattle prosper here without those famous bareros, or muriatiferous lands, which abound in the Pampas of Buenos Ayres.* (* Known in North America under the name of salt-licks.)

After having wandered for a long time, and without any traces of a road, in the desert savannahs of the Mesa de Pavones, we were agreeably surprised when we came to a solitary farm, the Hato de Alta Gracia, surrounded with gardens and basins of limpid water. Hedges of bead-trees encircled groups of icacoes laden with fruit. Farther on we passed the night near the small village of San Geronymo del Guayaval, founded by Capuchin missionaries. It is situated near the banks of the Rio Guarico, which falls into the Apure. I visited the missionary, who had no other habitation than his church, not having yet built a house. He was a young man, and he received us in the most obliging manner, giving us all the information we desired. His village, or to use the word established among the monks, his Mission, was not easy to govern. The founder, who had not hesitated to establish for his own profit a pulperia, in other words, to sell bananas and guarapo in the church itself, had shown himself to be not very nice in the choice of the new colonists. Many marauders of the Llanos had settled at Guayaval, because the inhabitants of a Mission are exempt from the authority of secular law. Here, as in Australia, it cannot be expected that good colonists will be formed before the second or third generation.

We passed the Guarico, and encamped in the savannahs south of Guayaval. Enormous bats, no doubt of the tribe of Phyllostomas, hovered as usual over our hammocks during a great part of the night. Every moment they seemed to be about to fasten on our faces. Early in the morning we pursued our way over low grounds, often inundated. In the season of rains, a boat may be navigated, as on a lake, between the Guarico and the Apure. We arrived on the 27th of March at the Villa de San Fernando, the capital of the Mission of the Capuchins in the province of Varinas. This was the termination of our journey over the Llanos; for we passed the three months of April, May, and June on the rivers.

CHAPTER 2.18.

SAN FERNANDO DE APURE. INTERTWININGS AND BIFURCATIONS OF THE RIVERS APURE AND ARAUCA. NAVIGATION ON THE RIO APURE.

Till the second half of the eighteenth century the names of the great rivers Apure, Arauca, and Meta were scarcely known in Europe: certainly less than they had been in the two preceding centuries, when the valiant Felipe de Urre and the conquerors of Tocuyo traversed the Llanos, to seek, beyond the Apure, the great legendary city of El Dorado, and the rich country of the Omeguas, the Timbuctoo of the New Continent. Such daring expeditions could not be carried out without all the apparatus of war; and the weapons, which had been destined for the defence of the new colonists, were employed without intermission against the unhappy natives. When more peaceful times succeeded to those of violence and public calamity, two powerful Indian tribes, the Cabres and the Caribs of the Orinoco, made themselves masters of the country which the Conquistadores had ceased to ravage. None but poor monks were then permitted to advance to the south of the steppes. Beyond the Uritucu an unknown world opened to the Spanish colonists; and the descendants of those intrepid warriors who had extended their conquests from Peru to the coasts of New Grenada and the mouth of the Amazon, knew not the roads that lead from Coro to the Rio Meta. The shore of Venezuela remained a separate country; and the slow conquests of the Jesuit missionaries were successful only by skirting the banks of the Orinoco. These fathers had already penetrated beyond the great cataracts of Atures and Maypures, when the Andalusian Capuchins had scarcely reached the plains of Calabozo, from the coast and the valleys of Aragua. It would be difficult to explain these contrasts by the system according to which the different monastic orders are governed; for the aspect of the country contributes powerfully to the more or less rapid progress of the Missions. They extend but slowly into the interior of the land, over mountains, or in steppes, wherever they do not follow the course of a particular river. It will scarcely be believed, that the Villa de Fernando de Apure, only fifty leagues distant in a direct line from that part of the coast of Caracas which has been longest inhabited, was founded at no earlier a date than 1789. We were shown a parchment, full of fine paintings, containing the privileges of this little town. The parchment was sent from Madrid at the solicitation of the monks, whilst yet only a few huts of reeds were to be seen around a great cross raised in the centre of the hamlet. The missionaries and the secular governments being alike interested in exaggerating in Europe what they have done to augment the culture and population of the provinces beyond the sea, it often happens that names of towns and villages are placed on the list of new conquests, long before their foundation.

The situation of San Fernando, on a large navigable river, near the mouth of another river which traverses the whole province of Varinas, is extremely advantageous for trade. Every production of that province, hides, cacao, cotton, and the indigo of Mijagual, which is of the first quality, passes through this town towards the mouths of the Orinoco. During the season of rains large vessels go from Angostura as far as San Fernando de Apure, and by the Rio Santo Domingo as far as Torunos, the port of the town of Varinas. At that period the inundations of the rivers, which form a labyrinth of branches between the Apure, the Arauca, the Capanaparo, and the Sinaruco, cover a country of nearly four hundred square leagues. At this point, the Orinoco, turned aside from its course, not by neighbouring mountains, but by the rising of counterslopes, runs eastward instead of following its previous direction in the line of the meridian. Considering the surface of the globe as a polyhedron, formed of planes variously inclined, we may conceive by the mere inspection of the maps, that the intersection of these slopes, rising towards the north, the west, and south,* between San Fernando de Apure, Caycara, and the mouth of the Meta, must cause a considerable depression. (* The risings towards the north and west are connected with two lines of ridges, the mountains of Villa de Cura and of Merida. The third slope, running from north to south, is that of the land-strait between the Andes and the chain of Parime. It determines the general inclination of the Orinoco, from the mouth of the Guaviare to that of the Apure.) The savannahs in this basin are covered with twelve or fourteen feet of water, and present, at the period of rains, the aspect of a great lake. The farms and villages which seem as if situated on shoals, scarcely rise two or three feet above the surface of the water. Everything here calls to mind the inundations of Lower Egypt, and the lake of Xarayes, heretofore so celebrated among geographers, though it exists only during some months of the year. The swellings of the rivers Apure, Meta, and Orinoco, are also periodical. In the rainy season, the horses that wander in the savannah, and have not time to reach the rising grounds of the Llanos, perish by hundreds. The mares are seen, followed by their colts,* swimming during a part of the day to feed upon the grass, the tops of which alone wave above the waters. (The colts are drowned everywhere in large numbers, because they are sooner tired of swimming, and strive to follow the mares in places where the latter alone can touch the ground.) In this state they are pursued by the crocodiles, and it is by no means uncommon to find the prints of the teeth of these carnivorous reptiles on their thighs. The carcases of horses, mules, and cows, attract an innumerable quantity of vultures. The zamuros are the ibisis of this country, and they render the same service to the inhabitants of the Llanos as the Vultur percnopterus to the inhabitants of Egypt.

We cannot reflect on the effects of these inundations without admiring the prodigious pliability of the organization of the animals which man has subjected to his sway. In Greenland the dog eats the refuse of the fisheries; and when fish are wanting, feeds on seaweed. The ass and the horse, originally natives of the cold and barren plains of Upper Asia, follow man to the New World, return to the wild state, and lead a restless and weary life in the burning climates of the tropics. Pressed alternately by excess of drought and of humidity, they sometimes seek a pool in the midst of a bare and dusty plain, to quench their thirst; and at other times flee from water, and the overflowing rivers, as menaced by an enemy that threatens them on all sides. Tormented during the day by gadflies and mosquitos, the horses, mules, and cows find themselves attacked at night by enormous bats, which fasten on their backs, and cause wounds that become dangerous, because they are filled with acaridae and other hurtful insects. In the time of great drought the mules gnaw even the thorny cactus* in order to imbibe its cooling juice, and draw it forth as from a vegetable fountain. (* The asses are particularly adroit in extracting the moisture contained in the Cactus melocatus. They push aside the thorns with their hoofs; but sometimes lame themselves in performing this feat.) During the great inundations these same animals lead an amphibious life, surrounded by crocodiles, water-serpents, and manatees. Yet, such are the immutable laws of nature, that their races are preserved in the struggle with the elements, and amid so many sufferings and dangers. When the waters retire, and the rivers return again into their beds, the savannah is overspread with a beautiful scented grass; and the animals of Europe and Upper Asia seem to enjoy, as in their native climes, the renewed vegetation of spring.

During the time of great floods, the inhabitants of these countries, to avoid the force of the currents, and the danger arising from the trunks of trees which these currents bring down, instead of ascending the beds of rivers in their boats, cross the savannahs. To go from San Fernando to the villages of San Juan de Payara, San Raphael de Atamaica, or San Francisco de Capanaparo, they direct their course due south, as if they were crossing a single river of twenty leagues broad. The junctions of the Guarico, the Apure, the Cabullare, and the Arauca with the Orinoco, form, at a hundred and sixty leagues from the coast of Guiana, a kind of interior Delta, of which hydrography furnishes few examples in the Old World. According to the height of the mercury in the barometer, the waters of the Apure have only a fall of thirty-four toises from San Fernando to the sea. The fall from the mouths of the Osage and the Missouri to the bar of the Mississippi is not more considerable. The savannahs of Lower Louisiana everywhere remind us of the savannahs of the Lower Orinoco.

During our stay of three days in the little town of San Fernando, we lodged with the Capuchin missionary, who lived much at his ease. We were recommended to him by the bishop of Caracas, and he showed us the most obliging attention. He consulted me on the works that had been undertaken to prevent the flood from undermining the shore on which the town was built. The flowing of the Portuguesa into the Apure gives the latter an impulse towards south-east; and, instead of procuring a freer course for the river, attempts were made to confine it by dykes and piers. It was easy to predict that these would be rapidly destroyed by the swell of the waters, the shore having been weakened by taking away the earth from behind the dyke to employ it in these hydraulic constructions.

San Fernando is celebrated for the excessive heat which prevails there the greater part of the year; and before I begin the recital of our long navigation on the rivers, I shall relate some facts calculated to throw light on the meteorology of the tropics. We went, provided with thermometers, to the flat shores covered with white sand which border the river Apure. At two in the afternoon I found the sand, wherever it was exposed to the sun, at 52.5 degrees. The instrument, raised eighteen inches above the sand, marked 42.8 degrees, and at six feet high 38.7 degrees. The temperature of the air under the shade of a ceiba was 36.2 degrees. These observations were made during a dead calm. As soon as the wind began to blow, the temperature of the air rose 3 degrees higher, yet we were not enveloped by a wind of sand, but the strata of air had been in contact with a soil more strongly heated, or through which whirlwinds of sand had passed. This western part of the Llanos is the hottest, because it receives air that has already crossed the rest of the barren steppe. The same difference has been observed between the eastern and western parts of the deserts of Africa, where the trade-winds blow.

The heat augments sensibly in the Llanos during the rainy season, particularly in the month of July, when the sky is cloudy, and reflects the radiant heat toward the earth. During this season the breeze entirely ceases; and, according to good thermometrical observations made by M. Pozo, the thermometer rises in the shade to 39 and 39.5 degrees, though kept at the distance of more than fifteen feet from the ground. As we approached the banks of the Portuguesa, the Apure, and the Apurito, the air became cooler from the evaporation of so considerable a mass of water. This effect is more especially perceptible at sunset. During the day the shores of the rivers, covered with white sand, reflect the heat in an insupportable degree, even more than the yellowish brown clayey grounds of Calabozo and Tisnao.

On the 28th of March I was on the shore at sunrise to measure the breadth of the Apure, which is two hundred and six toises. The thunder rolled in all directions around. It was the first storm and the first rain of the season. The river was swelled by the easterly wind; but it soon became calm, and then some great cetacea, much resembling the porpoises of our seas, began to play in long files on the surface of the water. The slow and indolent crocodiles seem to dread the neighbourhood of these animals, so noisy and impetuous in their evolutions, for we saw them dive whenever they approached. It is a very extraordinary phenomenon to find cetacea at such a distance from the coast. The Spaniards of the Missions designate them, as they do the porpoises of the ocean, by the name of toninas. The Tamanacs call them orinucna. They are three or four feet long; and bending their back, and pressing with their tail on the inferior strata of the water, they expose to view a part of the back and of the dorsal fin. I did not succeed in obtaining any, though I often engaged Indians to shoot at them with their arrows. Father Gili asserts that the Gumanos eat their flesh. Are these cetacea peculiar to the great rivers of South America, like the manatee, which, according to Cuvier, is also a fresh water cetaceous animal? or must we admit that they go up from the sea against the current, as the beluga sometimes does in the rivers of Asia? What would lead me to doubt this last supposition is, that we saw toninas above the great cataracts of the Orinoco, in the Rio Atabapo. Did they penetrate into the centre of equinoctial America from the mouth of the Amazon, by the communication of that river with the Rio Negro, the Cassiquiare, and the Orinoco? They are found here at all seasons, and nothing seems to denote that they make periodical migrations like salmon.

While the thunder rolled around us, the sky displayed only scattered clouds, that advanced slowly toward the zenith, and in an opposite direction. The hygrometer of Deluc was at 53 degrees, the centigrade thermometer 23.7 degrees, and Saussure's hygrometer 87.5 degrees. The electrometer gave no sign of electricity. As the storm gathered, the blue of the sky changed at first to deep azure and then to grey. The vesicular vapour became visible, and the thermometer rose three degrees, as is almost always the case, within the tropics, from a cloudy sky which reflects the radiant heat of the soil. A heavy rain fell. Being sufficiently habituated to the climate not to fear the effect of tropical rains, we remained on the shore to observe the electrometer. I held it more than twenty minutes in my hand, six feet above the ground, and observed that in general the pith-balls separated only a few seconds before the lightning was seen. The separation was four lines. The electric charge remained the same during several minutes; and having time to determine the nature of the electricity, by approaching a stick of sealing-wax, I saw here what I had often observed on the ridge of the Andes during a storm, that the electricity of the atmosphere was first positive, then nil, and then negative. These oscillations from positive to negative were often repeated. Yet the electrometer constantly denoted, a little before the lightning, only E., or positive E., and never negative E. Towards the end of the storm the west wind blew very strongly. The clouds dispersed, and the thermometer sunk to 22 degrees on account of the evaporation from the soil, and the freer radiation towards the sky.

I have entered into these details on the electric charge of the atmosphere because travellers in general confine themselves to the description of the impressions produced on a European newly arrived by the solemn spectacle of a tropical storm. In a country where the year is divided into great seasons of drought and wet, or, as the Indians say in their expressive language, of sun* (* In the Maypure dialect camoti, properly the heat [of the sun]. The Tamanacs call the season of drought uamu, the time of grasshoppers.) and rain* (* In the Tamanac language canepo. The year is designated, among several nations, by the name of one of the two seasons. The Maypures say, so many suns, (or rather so many heats;) the Tamanacs, so many rains.), it is highly interesting to follow the progress of meteorological phenomena in the transition from one season to another. We had already observed, in the valleys of Aragua from the 18th and 19th of February, clouds forming at the commencement of the night. In the beginning of the month of March the accumulation of the vesicular vapours, visible to the eye, and with them signs of atmospheric electricity, augmented daily. We saw flashes of heat-lightning to the south; and the electrometer of Volta constantly displayed, at sunset, positive electricity. The pith balls, unexcited during the day, separated to the width of three or four lines at the commencement of the night, which is triple what I generally observed in Europe, with the same instrument, in calm weather. Upon the whole, from the 26th of May, the electrical equilibrium of the atmosphere seemed disturbed. During whole hours the electricity was nil, then it became very strong, and soon after was again imperceptible. The hygrometer of Deluc continued to indicate great dryness (from 33 to 35 degrees), and yet the atmosphere appeared no longer the same. Amidst these perpetual variations of the electric state of the air, the trees, divested of their foliage, already began to unfold new leaves, and seemed to feel the approach of spring.

The variations which we have just described are not peculiar to one year. Everything in the equinoctial zone has a wonderful uniformity of succession, because the active powers of nature limit and balance each other, according to laws that are easily recognized. I shall here note the progress of atmospherical phenomena in the islands to the east of the Cordilleras of Merida and of New Grenada, in the Llanos of Venezuela and the Rio Meta, from four to ten degrees of north latitude, wherever the rains are constant from May to October, and comprehending consequently the periods of the greatest heats, which occur in July and August.* (* The maximum of the heat is not felt on the coast, at Cumana, at La Guayra, and in the neighbouring island of Margareta, before the month of September; and the rains, if the name can be given to a few drops that fall at intervals, are observed only in the months of October and November.)

Nothing can equal the clearness of the atmosphere from the month of December to that of February. The sky is then constantly without clouds; and if one should appear, it is a phenomenon that engages the whole attention of the inhabitants. A breeze from the east, and from east-north-east, blows with violence. As it brings with it air always of the same temperature, the vapours cannot become visible by cooling.

About the end of February and the beginning of March, the blue of the sky is less intense, the hygrometer indicates by degrees greater humidity, the stars are sometimes veiled by a slight stratum of vapour, and their light is no longer steady and planetary; they are seen twinkling from time to time when at 20 degrees above the horizon. The breeze at this period becomes less strong, less regular, and is often interrupted by dead calms. The clouds accumulate towards south-south-east, appearing like distant mountains, with outlines strongly marked. From time to time they detach themselves from the horizon, and traverse the vault of the sky with a rapidity which little corresponds with the feeble wind prevailing in the lower strata of the air. At the end of March, the southern region of the atmosphere is illumined by small electric explosions. They are like phosphorescent gleams, circumscribed by vapour. The breeze then shifts from time to time, and for several hours together, to the west and south-west. This is a certain sign of the approach of the rainy season, which begins at the Orinoco about the end of April. The blue sky disappears, and a grey tint spreads uniformly over it. At the same time the heat of the atmosphere progressively increases; and soon the heavens are no longer obscured by clouds, but by condensed vapours. The plaintive cry of the howling apes begins to be heard before sunrise. The atmospheric electricity, which, during the season of drought, from December to March, had been constantly, in the day-time, from 1.7 to 2 lines, becomes extremely variable from the month of March. It appears nil during whole days; and then for some hours the pith-balls diverge three or four lines. The atmosphere, which is generally, in the torrid as well as in the temperate zone, in a state of positive electricity, passes alternately, for eight or ten minutes, to the negative state. The season of rains is that of storms; and yet a great number of experiments made during three years, prove to me that it is precisely in this season of storms we find the smallest degree of electric tension in the lower regions of the atmosphere. Are storms the effect of this unequal charge of the different superincumbent strata of air? What prevents the electricity from descending towards the earth, in air which becomes more humid after the month of March? The electricity at this period, instead of being diffused throughout the whole atmosphere, appears accumulated on the exterior envelope, at the surface of the clouds. According to M. Gay-Lussac it is the formation of the cloud itself that carries the fluid toward its surface. The storm rises in the plains two hours after the sun has passed the meridian; consequently a short time after the moment of the maximum of diurnal heat within the tropics. It is extremely rare in the islands to hear thunder during the night, or in the morning. Storms at night are peculiar to certain valleys of rivers, having a peculiar climate.

What then are the causes of this rupture of the equilibrium in the electric tension of the air? of this continual condensation of the vapours into water? of this interruption of the breezes? of this commencement and duration of the rainy seasons? I doubt whether electricity has any influence on the formation of vapours. It is rather the formation of these vapours that augments and modifies the electrical tension. North and south of the equator, storms or great explosions take place at the same time in the temperate and in the equinoctial zone. Is there an action propagated through the great aerial ocean from the temperate zone towards the tropics? How can it be conceived, that in that zone where the sun rises constantly to so great a height above the horizon, its passage through the zenith can have so powerful an influence on the meteorological variations? I am of opinion that no local cause determines the commencement of the rains within the tropics; and that a more intimate knowledge of the higher currents of air will elucidate these problems, so complicated in appearance. We can observe only what passes in the lower strata of the atmosphere. The Andes are scarcely inhabited beyond the height of two thousand toises; and at that height the proximity of the soil, and the masses of mountains, which form the shoals of the aerial ocean, have a sensible influence on the ambient air. What we observe on the table-land of Antisana is not what we should find at the same height in a balloon, hovering over the Llanos or the surface of the ocean.

We have just seen that the season of rains and storms in the northern equinoctial zone coincides with the passage of the sun through the zenith of the place,* (* These passages take place, in the fifth and tenth degrees of north latitude between the 3rd and the 16th of April, and between the 27th of August and the 8th of September.) with the cessation of the north-east breezes, and with the frequency of calms and bendavales, which are stormy winds from south-east and south-west, accompanied by a cloudy sky. I believe that, in reflecting on the general laws of the equilibrium of the gaseous masses constituting our atmosphere, we may find, in the interruption of the current that blows from an homonymous pole, in the want of the renewal of air in the torrid zone, and in the continued action of an ascending humid current, a very simple cause of the coincidence of these phenomena. While the north-easterly breeze blows with all its violence north of the equator, it prevents the atmosphere which covers the equinoctial lands and seas from saturating itself with moisture. The hot and moist air of the torrid zone rises aloft, and flows off again towards the poles; while inferior polar currents, bringing drier and colder strata, are every instant taking the place of the columns of ascending air. By this constant action of two opposite currents, the humidity, far from being accumulated in the equatorial region, is carried towards the cold and temperate regions. During this season of breezes, which is that when the sun is in the southern signs, the sky in the northern equinoctial zone is constantly serene. The vesicular vapours are not condensed, because the air, unceasingly renewed, is far from the point of saturation. In proportion as the sun, entering the northern signs, rises towards the zenith, the breeze from the north-east moderates, and by degrees entirely ceases. The difference of temperature between the tropics and the temperate northern zone is then the least possible. It is the summer of the boreal pole; and, if the mean temperature of the winter, between 42 and 52 degrees of north latitude, be from 20 to 26 degrees of the centigrade thermometer less than the equatorial heat, the difference in summer is scarcely from 4 to 6 degrees. The sun being in the zenith, and the breeze having ceased, the causes which produce humidity, and accumulate it in the northern equinoctial zone, become at once more active. The column of air reposing on this zone, is saturated with vapours, because it is no longer renewed by the polar current. Clouds form in this air saturated and cooled by the combined effects of radiation and the dilatation of the ascending air. This air augments its capacity for heat in proportion as it rarefies. With the formation and collection of the vesicular vapours, electricity accumulates in the higher regions of the atmosphere. The precipitation of the vapours is continual during the day; but it generally ceases at night, and frequently even before sunset. The showers are regularly more violent, and accompanied with electric explosions, a short time after the maximum of the diurnal heat. This state of things remains unchanged, till the sun enters into the southern signs. This is the commencement of cold in the northern temperate zone. The current from the north-pole is then re-established, because the difference between the heat of the equinoctial and temperate regions augments daily. The north-east breeze blows with violence, the air of the tropics is renewed, and can no longer attain the degree of saturation. The rains consequently cease, the vesicular vapour is dissolved, and the sky resumes its clearness and its azure tint. Electrical explosions are no longer heard, doubtless because electricity no longer comes in contact with the groups of vesicular vapours in the high regions of the air, I had almost said the coating of clouds, on which the fluid can accumulate.