We remained a month longer at Cumana, employing ourselves in the necessary preparations for our proposed visit to the Orinoco and the Rio Negro. We had to choose such instruments as could be most easily transported in narrow boats; and to engage guides for an inland journey of ten months, across a country without communication with the coasts. The astronomical determination of places being the most important object of this undertaking, I felt desirous not to miss the observation of an eclipse of the sun, which was to be visible at the end of October: and in consequence I preferred remaining till that period at Cumana, where the sky is generally clear and serene. It was now too late to reach the banks of the Orinoco before October; and the high valleys of Caracas promised less favourable opportunities, on account of the vapours which accumulate round the neighbouring mountains.
I was, however, near being compelled by a deplorable occurrence, to renounce, or at least to delay for a long time, my journey to the Orinoco. On the 27th of October, the day before the eclipse, we went as usual, to take the air on the shore of the gulf, and to observe the instant of high water, which in those parts is only twelve or thirteen inches. It was eight in the evening, and the breeze was not yet stirring. The sky was cloudy; and during a dead calm it was excessively hot. We crossed the beach which separates the suburb of the Guayqueria Indians from the embarcadero. I heard some one walking behind us, and on turning, I saw a tall man of the colour of the Zambos, naked to the waist. He held almost over my head a macana, which is a great stick of palm-tree wood, enlarged to the end like a club. I avoided the stroke by leaping towards the left; but M. Bonpland, who walked on my right, was less fortunate. He did not see the Zambo so soon as I did, and received a stroke above the temple, which levelled him with the ground. We were alone, without arms, half a league from any habitation, on a vast plain bounded by the sea. The Zambo, instead of attacking me, moved off slowly to pick up M. Bonpland’s hat, which, having somewhat deadened the violence of the blow, had fallen off and lay at some distance. Alarmed at seeing my companion on the ground, and for some moments senseless, I thought of him only. I helped him to raise himself, and pain and anger doubled his strength. We ran toward the Zambo, who, either from cowardice, common enough in people of this caste, or because he perceived at a distance some men on the beach, did not wait for us, but ran off in the direction of the Tunal, a little thicket of cactus and arborescent avicennia. He chanced to fall in running; and M. Bonpland, who reached him first, seized him round the body. The Zambo drew a long knife; and in this unequal struggle we should infallibly have been wounded, if some Biscayan merchants, who were taking the air on the beach, had not come to our assistance. The Zambo seeing himself surrounded, thought no longer of defence. He again ran away, and we pursued him through the thorny cactuses. At length, tired out, he took shelter in a cow-house, whence he suffered himself to be quietly led to prison.
M. Bonpland was seized with fever during the night; but being endowed with great energy and fortitude, and possessing that cheerful disposition which is one of the most precious gifts of nature, he continued his labours the next day. The stroke of the macana had extended to the top of his head, and he felt its effect for the space of two or three months during the stay we made at Caracas. When stooping to collect plants, he was sometimes seized with giddiness, which led us to fear that an internal abscess was forming. Happily these apprehensions were unfounded, and the symptoms, at first alarming, gradually disappeared. The inhabitants of Cumana showed us the kindest interest. It was ascertained that the Zambo was a native of one of the Indian villages which surround the great lake of Maracaybo. He had served on board a privateer belonging to the island of St. Domingo, and in consequence of a quarrel with the captain he had been left on the coast of Cumana, when the ship quitted the port. Having seen the signal which we had fixed up for the purpose of observing the height of the tides, he had watched the moment when he could attack us on the beach. But why, after having knocked one of us down, was he satisfied with simply stealing a hat? In an examination he underwent, his answers were so confused and stupid, that it was impossible to clear up our doubts. Sometimes he maintained that his intention was not to rob us; but that, irritated by the bad treatment he had suffered on board the privateer of St. Domingo, he could not resist the desire of attacking us, when he heard us speak French. Justice is so tardy in this country, that prisoners, of whom the jail is full, may remain seven or eight years without being brought to trial; we learnt, therefore, with some satisfaction, that a few days after our departure from Cumana, the Zambo had succeeded in breaking out of the castle of San Antonio.
On the day after this occurrence, the 28th of October, I was, at five in the morning, on the terrace of our house, making preparations for the observation of the eclipse. The weather was fine and serene. The crescent of Venus, and the constellation of the Ship, so splendid from the disposition of its immense nebulae, were lost in the rays of the rising sun. I had a complete observation of the progress and the close of the eclipse. I determined the distance of the horns, or the differences of altitude and azimuth, by the passage over the threads of the quadrant. The eclipse terminated at 2 hours 14 minutes 23.4 seconds mean time, at Cumana.
During a few days which preceded and followed the eclipse of the sun, very remarkable atmospherical phenomena were observable. It was what is called in those countries the season of winter; that is, of clouds and small electrical showers. From the 10th of October to the 3rd of November, at nightfall, a reddish vapour arose in the horizon, and covered, in a few minutes, with a veil more or less thick, the azure vault of the sky. Saussure’s hygrometer, far from indicating greater humidity, often went back from 90 to 83°. The heat of the day was from 28 to 32°, which for this part of the torrid zone is very considerable. Sometimes, in the midst of the night, the vapours disappeared in an instant; and at the moment when I had arranged my instruments, clouds of brilliant whiteness collected at the zenith, and extended towards the horizon. On the 18th of October these clouds were so remarkably transparent, that they did not hide stars even of the fourth magnitude. I could distinguish so perfectly the spots of the moon, that it might have been supposed its disk was before the clouds. The latter were at a prodigious height, disposed in bands, and at equal distances, as from the effect of electric repulsions:— these small masses of vapour, similar to those I saw above my head on the ridge of the highest Andes, are, in several languages, designated by the name of sheep. When the reddish vapour spreads lightly over the sky, the great stars, which in general, at Cumana, scarcely scintillate below 20 or 25°, did not retain even at the zenith, their steady and planetary light. They scintillated at all altitudes, as after a heavy storm of rain.* It was curious that the vapour did not affect the hygrometer at the surface of the earth. I remained a part of the night seated in a balcony, from which I had a view of a great part of the horizon. In every climate I feel a peculiar interest in fixing my eyes, when the sky is serene, on some great constellation, and seeing groups of vesicular vapours appear and augment, as around a central nucleus, then, disappearing, form themselves anew.
[* I have not observed any direct relation between the scintillation of the stars and the dryness of that part of the atmosphere open to our researches. I have often seen at Cumana a great scintillation of the stars of Orion and Sagittarius, when Saussure’s hygrometer was at 85°. At other times, these same stars, considerably elevated above the horizon, emitted a steady and planetary light, the hygrometer being at 90 or 93°. Probably it is not the quantity of vapour, but the manner in which it is diffused, and more or less dissolved in the air, which determines the scintillation. The latter is invariably attended with a coloration of light. It is remarkable enough, that, in northern countries, at a time when the atmosphere appears perfectly dry, the scintillation is most decided in very cold weather.]
After the 28th of October, the reddish mist became thicker than it had previously been. The heat of the nights seemed stifling, though the thermometer rose only to 26°. The breeze, which generally refreshed the air from eight or nine o’clock in the evening, was no longer felt. The atmosphere was burning hot, and the parched and dusty ground was cracked on every side. On the 4th of November, about two in the afternoon, large clouds of peculiar blackness enveloped the high mountains of the Brigantine and the Tataraqual. They extended by degrees as far as the zenith. About four in the afternoon thunder was heard over our heads, at an immense height, not regularly rolling, but with a hollow and often interrupted sound. At the moment of the strongest electric explosion, at 4 hours 12 minutes, there were two shocks of earthquake, which followed each other at the interval of fifteen seconds. The people ran into the streets, uttering loud cries. M. Bonpland, who was leaning over a table examining plants, was almost thrown on the floor. I felt the shock very strongly, though I was lying in a hammock. Its direction was from north to south, which is rare at Cumana. Slaves, who were drawing water from a well more than eighteen or twenty feet deep, near the river Manzanares, heard a noise like the explosion of a strong charge of gunpowder. The noise seemed to come from the bottom of the well; a very curious phenomenon, though very common in most of the countries of America which are exposed to earthquakes.
A few minutes before the first shock there was a very violent blast of wind, followed by electrical rain falling in great drops. I immediately tried the atmospherical electricity by the electrometer of Volta. The small balls separated four lines; the electricity often changed from positive to negative, as is the case during storms, and, in the north of Europe, even sometimes in a fall of snow. The sky remained cloudy, and the blast of wind was followed by a dead calm, which lasted all night. The sunset presented a picture of extraordinary magnificence. The thick veil of clouds was rent asunder, as in shreds, quite near the horizon; the sun appeared at 12° of altitude on a sky of indigo-blue. Its disk was enormously enlarged, distorted, and undulated toward the edges. The clouds were gilded; and fascicles of divergent rays, reflecting the most brilliant rainbow hues, extended over the heavens. A great crowd of people assembled in the public square. This celestial phenomenon — the earthquake — the thunder which accompanied it — the red vapour seen during so many days, all were regarded as the effect of the eclipse.
About nine in the evening there was another shock, much slighter than the former, but attended with a subterraneous noise. The barometer was a little lower than usual; but the progress of the horary variations or small atmospheric tides, was no way interrupted. The mercury was precisely at the minimum of height at the moment of the earthquake; it continued rising till eleven in the evening, and sank again till half after four in the morning, conformably to the law which regulates barometrical variations. In the night between the 3rd and 4th of November the reddish vapour was so thick that I could not distinguish the situation of the moon, except by a beautiful halo of 20° diameter.
Scarcely twenty-two months had elapsed since the town of Cumana had been almost totally destroyed by an earthquake. The people regard vapours which obscure the horizon, and the subsidence of wind during the night, as infallible pregnostics of disaster. We had frequent visits from persons who wished to know whether our instruments indicated new shocks for the next day; and alarm was great and general when, on the 5th of November, exactly at the same hour as on the preceding day, there was a violent gust of wind, attended by thunder, and a few drops of rain. No shock was felt. The wind and storm returned during five or six days at the same hour, almost at the same minute. The inhabitants of Cumana, and of many other places between the tropics, have long since observed that atmospherical changes, which are, to appearance, the most accidental, succeed each other for whole weeks with astonishing regularity. The same phenomenon occurs in summer, in the temperate zone; nor has it escaped the perception of astronomers, who often observe, in a serene sky, during three or four days successively, clouds which have collected at the same part of the firmament, take the same direction, and dissolve at the same height; sometimes before, sometimes after the passage of a star over the meridian, consequently within a few minutes of the same point of true time.*
[* M. Arago and I paid a great deal of attention to this phenomenon during a long series of observations made in the year 1809 and 1810, at the Observatory of Paris, with the view of verifying the declination of the stars.]
The earthquake of the 4th of November, the first I had felt, made the greater impression on me, as it was accompanied with remarkable meteorological variations. It was, moreover, a positive movement upward and downward, and not a shock by undulation. I did not then imagine, that after a long abode on the table-lands of Quito and the coasts of Peru, I should become almost as familiar with the abrupt movements of the ground as we are in Europe with the sound of thunder. In the city of Quito, we never thought of rising from our beds when, during the night, subterraneous rumblings (bramidos), which seem always to come from the volcano of Pichincha, announced a shock, the force of which, however, is seldom in proportion to the intensity of the noise. The indifference of the inhabitants, who bear in mind that for three centuries past their city has not been destroyed, readily communicates itself to the least intrepid traveller. It is not so much the fear of the danger, as the novelty of the sensation, which makes so forcible an impression when the effect of the slightest earthquake is felt for the first time.
From our infancy, the idea of certain contrasts becomes fixed in our minds: water appears to us an element that moves; earth, a motionless and inert mass. These impressions are the result of daily experience; they are connected with everything that is transmitted to us by the senses. When the shock of an earthquake is felt, when the earth which we had deemed so stable is shaken on its old foundations, one instant suffices to destroy long-fixed illusions. It is like awakening from a dream; but a painful awakening. We feel that we have been deceived by the apparent stability of nature; we become observant of the least noise; we mistrust for the first time the soil we have so long trod with confidence. But if the shocks be repeated, if they become frequent during several successive days, the uncertainty quickly disappears. In 1784, the inhabitants of Mexico were accustomed to hear the thunder roll beneath their feet,* as it is heard by us in the region of the clouds. Confidence easily springs up in the human breast: on the coasts of Peru we become accustomed to the undulations of the ground, as the sailor becomes accustomed to the tossing of the ship, caused by the motion of the waves.
[* Los bramidos de Guanazuato.]
The reddish vapour which at Cumana had spread a mist over the horizon a little before sunset, disappeared after the 7th of November. The atmosphere resumed its former purity, and the firmament appeared, at the zenith, of that deep blue tint peculiar to climates where heat, light, and a great equality of electric charge seem all to promote the most perfect dissolution of water in the air. I observed, on the night of the 7th, the immersion of the second satellite of Jupiter. The belts of the planet were more distinct than I had ever seen them before.
I passed a part of the night in comparing the intensity of the light emitted by the beautiful stars which shine in the southern sky. I pursued this task carefully in both hemispheres, at sea, and during my abode at Lima, at Guayaquil, and at Mexico. Nearly half a century has now elapsed since La Caille examined that region of the sky which is invisible in Europe. The stars near the south pole are usually observed with so little perseverance and attention, that the greatest changes may take place in the intensity of their light and their own motion, without astronomers having the slightest knowledge of them. I think I have remarked changes of this kind in the constellation of the Crane and in that of the Ship. I compared, at first with the naked eye, the stars which are not very distant from each other, for the purpose of classing them according to the method pointed out by Herschel, in a paper read to the Royal Society of London in 1796. I afterwards employed diaphragms diminishing the aperture of the telescope, and coloured and colourless glasses placed before the eye-glass. I moreover made use of an instrument of reflexion calculated to bring simultaneously two stars into the field of the telescope, after having equalized their light by receiving it with more or fewer rays at pleasure, reflected by the silvered part of the mirror. I admit that these photometric processes are not very precise; but I believe the last, which perhaps had never before been employed, might he rendered nearly exact, by adding a scale of equal parts to the moveable frame of the telescope of the sextant. It was by taking the mean of a great number of valuations, that I saw the relative intensity of the light of the great stars decrease in the following manner: Sirius, Canopus, a Centauri, Acherner, b Centauri, Fomalhaut, Rigel, Procyon, Betelgueuse, e of the Great Dog, d of the Great Dog, a of the Crane, a of the Peacock. These experiments will become more interesting when travellers shall have determined anew, at intervals of forty or fifty years, some of those changes which the celestial bodies seem to undergo, either at their surface or with respect to their distances from our planetary system.
After having made astronomical observations with the same instruments, in our northern climates and in the torrid zone, we are surprised at the effect produced in the latter (by the transparency of the air, and the less extinction of light), on the clearness with which the double stars, the satellites of Jupiter, or certain nebulae, present themselves. Beneath a sky equally serene in appearance, it would seem as if more perfect instruments were employed; so much more distinct and well defined do the objects appear between the tropics. It cannot be doubted, that at the period when equinoctial America shall become the centre of extensive civilization, physical astronomy will make immense improvements, in proportion as the skies will be explored with excellent glasses, in the dry and hot climates of Cumana, Coro, and the island of Margareta. I do not here mention the ridge of the Cordilleras, because, with the exception of some high and nearly barren plains in Mexico and Peru, the very elevated table-lands, in which the barometric pressure is from ten to twelve inches less than at the level of the sea, have a misty and extremely variable climate. The extreme purity of the atmosphere which constantly prevails in the low regions during the dry season, counterbalances the elevation of site and the rarity of the air on the table-lands. The elevated strata of the atmosphere, when they envelope the ridges of mountains, undergo rapid changes in their transparency.
The night of the 11th of November was cool and extremely fine. From half after two in the morning, the most extraordinary luminous meteors were seen in the direction of the east. M. Bonpland, who had risen to enjoy the freshness of the air, perceived them first. Thousands of bolides and falling stars succeeded each other during the space of four hours. Their direction was very regular from north to south. They filled a space in the sky extending from due east 30° to north and south. In an amplitude of 60° the meteors were seen to rise above the horizon at east-north-east and at east, to describe arcs more or less extended, and to fall towards the south, after having followed the direction of the meridian. Some of them attained a height of 40°, and all exceeded 25 or 30°. There was very little wind in the low regions of the atmosphere, and that little blew from the east. No trace of clouds was to be seen. M. Bonpland states that, from the first appearance of the phenomenon, there was not in the firmament a space equal in extent to three diameters of the moon, which was not filled every instant with bolides and falling stars. The first were fewer in number, but as they were of different sizes, it was impossible to fix the limit between these two classes of phenomena. All these meteors left luminous traces from five to ten degrees in length, as often happens in the equinoctial regions. The phosphorescence of these traces, or luminous bands, lasted seven or eight seconds. Many of the falling stars had a very distinct nucleus, as large as the disk of Jupiter, from which darted sparks of vivid light. The bolides seem to burst as by explosion; but the largest, those from 1 to 1 degree 15 minutes in diameter, disappeared without scintillation, leaving behind them phosphorescent bands (trabes) exceeding in breadth fifteen or twenty minutes. The light of these meteors was white, and not reddish, which must doubtless be attributed to the absence of vapour and the extreme transparency of the air. For the same reason, within the tropics, the stars of the first magnitude have, at their rising, a light decidedly whiter than in Europe.
Almost all the inhabitants of Cumana witnessed this phenomenon, because they had left their houses before four o’clock, to attend the early morning mass. They did not behold these bolides with indifference; the oldest among them remembered that the great earthquakes of 1766 were preceded by similar phenomena. The Guaiqueries in the Indian suburb alleged “that the bolides began to appear at one o’clock; and that as they returned from fishing in the gulf, they had perceived very small falling stars towards the east.” They assured us that igneous meteors were extremely rare on those coasts after two o’clock in the morning.
The phenomenon ceased by degrees after four o’clock, and the bolides and falling stars became less frequent; but we still distinguished some to north-east by their whitish light, and the rapidity of their movement, a quarter of an hour after sunrise. This circumstance will appear less extraordinary, when I mention that in broad daylight, in 1788, the interior of the houses in the town of Popayan was brightly illumined by an aerolite of immense magnitude. It passed over the town, when the sun was shining clearly, about one o’clock. M. Bonpland and myself, during our second residence at Cumana, after having observed, on the 26th of September, 1800, the immersion of the first satellite of Jupiter, succeeded in seeing the planet distinctly with the naked eye, eighteen minutes after the disk of the sun had appeared in the horizon. There was a very slight vapour in the east, but Jupiter appeared on an azure sky. These facts bear evidence of the extreme purity and transparency of the atmosphere in the torrid zone. The mass of diffused light is the less, in proportion as the vapours are more perfectly dissolved. The same cause which checks the diffusion of the solar light, diminishes the extinction of that which emanates either from bolides from Jupiter, or from the moon, seen on the second day after its conjunction. The 12th of November was an extremely hot day, and the hygrometer indicated a very considerable degree of dryness for those climates. The reddish vapour clouded the horizon anew, and rose to the height of 14°. This was the last time it appeared that year; and I must here observe, that it is no less rare under the fine sky of Cumana, than it is common at Acapulco, on the western coast of Mexico.
We did not neglect, during the course of our journey from Caracas to the Rio Negro, to enquire everywhere, whether the meteors of the 12th of November had been perceived. In a wild country, where the greater number of the inhabitants sleep in the open air, so extraordinary a phenomenon could not fail to be remarked, unless it had been concealed from observation by clouds. The Capuchin missionary at San Fernando de Apure,* a village situated amid the savannahs of the province of Varinas; the Franciscan monks stationed near the cataracts of the Orinoco and at Maroa,* on the banks of the Rio Negro; had seen numberless falling-stars and bolides illumine the heavens. Maroa is south-west of Cumana, at one hundred and seventy-four leagues distance. All these observers compared the phenomenon to brilliant fireworks; and it lasted from three till six in the morning. Some of the monks had marked the day in their rituals; others had noted it by the proximate festivals of the Church. Unfortunately, none of them could recollect the direction of the meteors, or their apparent height. From the position of the mountains and thick forests which surround the Missions of the Cataracts and the little village of Maroa, I presume that the bolides were still visible at 20° above the horizon. On my arrival at the southern extremity of Spanish Guiana, at the little fort of San Carlos, I found some Portuguese, who had gone up the Rio Negro from the Mission of St. Joseph of the Maravitans. They assured me that in that part of Brazil the phenomenon had been perceived at least as far as San Gabriel das Cachoeiras, consequently as far as the equator itself.*
[* North latitude 7° 53′ 12″; west longitude 70° 20′.]
[* North latitude 2° 42′ 0″; west longitude 70° 21′.]
[* A little to the north-west of San Antonio de Castanheiro. I did not meet with any persons who had observed this meteor, at Santa Fe de Bogota, at Popayan, or in the southern hemisphere, at Quito and Peru. Perhaps the state of the atmosphere, so changeable in these western regions, prevented observation.]
I was forcibly struck by the immense height which these bolides must have attained, to have rendered them visible simultaneously at Cumana, and on the frontiers of Brazil, in a line of two hundred and thirty leagues in length. But what was my astonishment, when, on my return to Europe, I learned that the same phenomenon had been perceived on an extent of the globe of 64° of latitude, and 91° of longitude; at the equator, in South America, at Labrador, and in Germany! I saw accidentally, during my passage from Philadelphia to Bordeaux,* the corresponding observation of Mr. Ellicot (latitude 30° 42); and upon my return from Naples to Berlin, I read the account of the Moravian missionaries among the Esquimaux, in the Bibliothek of Gottingen.
[* In the Memoirs of the Pennsylvanian Society.]
The following is a succinct enumeration of the facts:
First. The fiery meteors were seen in the east, and the east-north-east, at 40° of elevation, from 2 to 6 a.m. at Cumana (latitude 10° 27′ 52″, longitude 66° 30′); at Porto Cabello (latitude 10° 6′ 52″, longitude 67° 5′); and on the frontiers of Brazil, near the equator, in longitude 70° west of the meridian of Paris.
Second. In French Guiana (latitude 4° 56′, longitude 54° 35′) “the northern part of the sky was suffused with fire. Numberless falling-stars traversed the heavens during the space of an hour and a half, and shed so vivid a light, that those meteors might be compared to the blazing sheaves which shoot out from fireworks.” The knowledge of this fact rests upon the highly trustworthy testimony of the Count de Marbois, then living in exile at Cayenne, a victim to his love of justice and of rational, constitutional liberty.
Third. Mr. Ellicot, astronomer to the United States, having completed his trigonometric operations for the rectification of the limits on the Ohio, being on the 12th of November in the gulf of Florida, in latitude 25°, and longitude 81° 50′, saw in all parts of the sky, “as many meteors as stars, moving in all directions. Some appeared to fall perpendicularly; and it was expected every minute that they would drop into the vessel.” The same phenomenon was perceived upon the American continent as far as latitude 30° 42′.
Fourth. In Labrador, at Nain (latitude 56° 55′), and Hoffenthal (latitude 58° 4′); in Greenland, at Lichtenau (latitude 61° 5′), and at New Herrnhut (latitude 64° 14′, longitude 52° 20′); the Esquimaux were terrified at the enormous quantity of bolides which fell during twilight at all points of the firmament, and some of which were said to be a foot broad.
Fifth. In Germany, Mr. Zeissing, vicar of Ittetsadt, near Weimar (latitude 50° 59′, longitude 9° 1 minute east), perceived, on the 12th of November, between the hours of six and seven in the morning (half-past two at Cumana), some falling-stars which shed a very white light. Soon after, in the direction of south and south-west, luminous rays appeared from four to six feet long; they were reddish, and resembled the luminous track of a sky-rocket. During the morning twilight, between the hours of seven and eight, the sky, in the direction of south-west, was observed from time to time to be brightly illumined by white lightning, running in serpentine lines along the horizon. At night the cold increased and the barometer rose. It is very probable, that the meteors might have been observed more to the east, in Poland and in Russia.*
[* In Paris and in London the sky was cloudy. At Carlsruhe, before dawn, lightning was seen in the north-west and south-east. On the 13th of November a remarkable glare of light was seen at the same place in the south-east.]
The distance from Weimar to the Rio Negro is 1800 nautical leagues; and from the Rio Negro to Herrnhut in Greenland, 1300 leagues. Admitting that the same fiery meteors were seen at points so distant from each other, we must suppose that their height was at least 411 leagues. Near Weimar, the appearance like sky-rockets was observed in the south and south-east; at Cumana, in the east and east-north-east. We may therefore conclude, that numberless aerolites must have fallen into the sea, between Africa and South America, westward of the Cape Verd Islands. But since the direction of the bolides was not the same at Labrador and at Cumana, why were they not perceived in the latter place towards the north, as at Cayenne? We can scarcely be too cautious on a subject, on which good observations made in very distant places are still wanting. I am rather inclined to think, that the Chayma Indians of Cumana did not see the same bolides as the Portuguese in Brazil and the missionaries in Labrador; but at the same time it cannot be doubted (and this fact appears to me very remarkable) that in the New World, between the meridians of 46 and 82°, between the equator and 64° north, at the same hour, an immense number of bolides and falling-stars were perceived; and that those meteors had everywhere the same brilliancy, throughout a space of 921,000 square leagues.
Astronomers who have lately been directing minute attention to falling-stars and their parallaxes, consider them as meteors belonging to the farthest limits of our atmosphere, between the region of the Aurora Borealis and that of the lightest clouds.* Some have been seen, which had not more than 14,000 toises, or about five leagues of elevation. The highest do not appear to exceed thirty leagues. They are often more than a hundred feet in diameter: and their swiftness is such, that they dart in a few seconds through a space of two leagues. Of some which have been measured, the direction was almost perpendicularly upward, or forming an angle of 50° with the vertical line. This extremely remarkable circumstance has led to the conclusion, that falling-stars are not aerolites which, after having hovered a long time in space, unite on accidentally entering into our atmosphere, and fall towards the earth.*
[* According to the observations which I made on the ridge of the Andes, at an elevation of 2700 toises, on the moutons, or little white fleecy clouds, it appeared to me, that their elevation is sometimes not less than 6000 toises above the level of the coast.]
[* M. Chladni, who at first considered falling-stars to be aerolites, subsequently abandoned that idea.]
Whatever may be the origin of these luminous meteors, it is difficult to conceive an instantaneous inflammation taking place in a region where there is less air than in the vacuum of our air-pumps; and where (at the height of 25,000 toises) the mercury in the barometer would not rise to 0.012 of a line. We have ascertained the uniform mixture of atmospheric air to be about 0. 003, only to an elevation of 3000 toises; consequently not beyond the last stratum of fleecy clouds. It may be admitted that, in the first revolutions of the globe, gaseous substances, which yet remain unknown to us, have risen towards that region through which the falling-stars pass; but accurate experiments, made upon mixtures of gases which have not the same specific gravity, show that there is no reason for supposing a superior stratum of the atmosphere entirely different from the inferior strata. Gaseous substances mingle and penetrate each other on the least movement; and a uniformity of their mixture may have taken place in the lapse of ages, unless we believe them to possess a repulsive action of which there is no example in those substances we can subject to our observations. Farther, if we admit the existence of particular aerial fluids in the inaccessible regions of luminous meteors, of falling-stars, bolides, and the Aurora Borealis; how can we conceive why the whole stratum of those fluids does not at once ignite, but that the gaseous emanations, like the clouds, occupy only limited spaces? How can we suppose an electrical explosion without some vapours collected together, capable of containing unequal charges of electricity, in air, the mean temperature of which is perhaps 25° below the freezing point of the centigrade thermometer, and the rarefaction of which is so considerable, that the compression of the electrical shock could scarcely disengage any heat? These difficulties would in great part be removed, if the direction of the movement of falling-stars allowed us to consider them as bodies with a solid nucleus, as cosmic phenomena (belonging to space beyond the limits of our atmosphere), and not as telluric phenomena (belonging to our planet only).
Supposing the meteors of Cumana to have been only at the usual height at which falling-stars in general move, the same meteors were seen above the horizon in places more than 310 leagues distant from each other.* How great a disposition to incandescence must have prevailed on the 12th November, in the higher regions of the atmosphere, to have rendered during four hours myriads of bolides and falling stars visible at the equator, in Greenland, and in Germany!
[* It was this circumstance that induced Lambert to propose the observation of falling-stars for the determination of terrestrial longitudes. He considered them to be celestial signals seen at great distances.]
M. Benzenberg observes, that the same cause which renders the phenomenon more frequent, has also an influence on the large size of the meteors, and the intensity of their light. In Europe, the greatest number of falling stars are seen on those nights on which very bright ones are mingled with very small ones. The periodical nature of the phenomenon augments the interest it excites. There are months in which M. Brandes has reckoned in our temperate zone only sixty or eighty falling-stars in one night; and in other months their number has risen to two thousand. Whenever one is observed, which has the diameter of Sirius or of Jupiter, we are sure of seeing the brilliant meteor succeeded by a great number of smaller ones. If the falling stars be very numerous during one night, it is probable that they will continue equally so during several weeks. It would seem, that in the higher regions of the atmosphere, near that extreme limit where the centrifugal force is balanced by gravity, there exists at regular periods a particular disposition for the production of bolides, falling-stars, and the Aurora Borealis.* Does the periodical recurrence of this great phenomenon depend upon the state of the atmosphere? or upon something which the atmosphere receives from without, while the earth advances in the ecliptic? Of all this we are still as ignorant as mankind were in the days of Anaxagoras.
[* Ritter, like several others, makes a distinction between bolides mingled with falling-stars and those luminous meteors which, enveloped in vapour and smoke, explode with great noise, and let fall (chiefly in the day-time) aerolites. The latter certainly do not belong to our atmosphere.]
With respect to the falling-stars themselves, it appears to me, from my own experience, that they are more frequent in the equinoctial regions than in the temperate zone; and more frequent above continents, and near certain coasts, than in the middle of the ocean. Do the radiation of the surface of the globe, and the electric charge of the lower regions of the atmosphere (which varies according to the nature of the soil and the positions of the continents and seas), exert their influence as far as those heights where eternal winter reigns? The total absence of even the smallest clouds, at certain seasons, or above some barren plains destitute of vegetation, seems to prove that this influence can be felt as far as five or six thousand toises high.
A phenomenon analogous to that which appeared on the 12th of November at Cumana, was observed thirty years previously on the table-land of the Andes, in a country studded with volcanoes. In the city of Quito there was seen in one part of the sky, above the volcano of Cayamba, such great numbers of falling-stars, that the mountain was thought to be in flames. This singular sight lasted more than an hour. The people assembled in the plain of Exido, which commands a magnificent view of the highest summits of the Cordilleras. A procession was on the point of setting out from the convent of San Francisco, when it was perceived that the blaze on the horizon was caused by fiery meteors, which ran along the skies in all directions, at the altitude of twelve or thirteen degrees.
Last updated Tuesday, August 25, 2015 at 14:10