Letter from M. A. Humboldt to C. Delambre, Member of the French National Inſtitute.

New Barcelona, Nov. 24, 1800.

DURING my ſtay in South America I diſpatched ſeveral letters to you and Lalande; I know you are intereſted in my fate, and I never let ſlip an opportunity of writing to you, though I have ſcarcely any hopes of my letters reaching the place of their deſtination.

I am now on the point of ſetting out for the Havannah and Mexico, after having performed a tour of thirteen hundred nautical leagues in this part of the New World, ſituated between Popayan, Quito, and Cayenne. I have ſlept for three months in the open air, in the woods, ſurrounded by tigers and hideous ſerpents, or on plains covered with crocodiles.

Bananas, rice, and manioc, have been our ſole nouriſhment; for all proviſions ſoon become putrid in this damp and ſcorching country.

How grand and majeſtic is nature among theſe mountains!

From Baraquan and Uruana, which unknown nations have covered with hieroglyphics, as far as the volcano of Duida, at the diſtance of ſixty leagues from the ſmall lake of Dorado, the elevation of which I have found to be 2176 metres, there is only one cordillera of granite, that deſcends from Quito, and proceeds from weſt to eaſt to join the mountains of the French part of Guyana.

What variety among the Indian races!

All free, all governing themſelves and eating each other, from the Guaicas of Gehetta, a pigmy nation, the largeſt of whom are about four feet two inches in height, to the white Guajaribos, who have really the whiteneſs of Europeans; from the Otomacos, who eat a pound and a half of earth per day, to the Marivitanos and the Magueritares, who feed on ants and reſin.

Having already ſpoken of all theſe in a letter, which I diſpatched from the mouths of the Orenoquo to our good friend Pommard, I ſhall confine myſelf at preſent to a few aſtronomical obſervations, which, I think, I have made with a conſiderable degree of care.

This letter, when this was publiſhed, had not reached France

My time-keeper, by Berthoud, continues to go with great correctneſs.

I regulate it every four, five, or ſix days, by correſponding altitudes, taken with my inſtruments, which do not err a ſecond; viz.

ſextants by Ramſden and Troughton, a quadrant by Bird, and a horizon by Carroché.

You know that I am not very learned in the mathematics, and that aſtronomy is not the object of my travels; yet with zeal and application, and by daily handling the ſame inſtruments, I have been able to do ſomething, and to do it better.

As I traverſed a country never viſited by Europeans till about thirty years ago, in which all the Chriſtian miſſions do not amount to 1800 ſouls, and conſequently where no one has ever yet been able to make obſervations, I conceived that I ought not to neglect ſo favourable an opportunity of enlarging our geographical knowledge.

You would have laughed had you ſeen me amidſt the Ydapamianeres Indians in the foreſt of Caſquiara, with my inſtruments mounted on boxes or trunks, while the ſhells of tortoiſes ſerved us as ſtools.

Eight or nine apes, which we carried with us, had a ſtrong deſire to handle my hygrometers, barometers, and electrometers alſo: around all theſe ten or twelve Indians ſtretched out in their hammocks, together with fires to ſecure us from the tigers, which are no leſs ferocious here than in Africa.

The want of nouriſhment, the moſquitoes, the ants; the chigers, which enter the ſkin and plough up the fleſh; the deſire of cooling ourſelves in the water, and the impoſſibility of doing it on account of the ferocity of the caymans, the danger of being pricked by the rajas and the teeth of the ſmall caribfiſh—youth and a great deal of reſignation are required to endure all theſe.

The evil is paſſed, and I have reaped more than I durſt venture to hope.

It is believed (ſee the map of father Caulin, the beſt extant, though all the names are wrong,) that the Spaniſh poſſeſſions of Guyana extend to the equator.

But I have found, by very good obſervations of the ſtars called the Croſs and Canopus, which I made among the rocks of Culimacari, that San Carlos del Rio Negro, the moſt ſouthern eſtabliſhment, is in 1° 53′ of north latitude; and that the line paſſes through the government of Great Para, near St. Gabriel-delas-Cachuellas, where there is a cataract, but not ſo conſiderable as the two famous ones of Atures and Maypura.

At Cumana, before the earthquake, which we experienced on the 4th of November 1799, the magnetic inclination, meaſured with Borda’s compaſs, was found to be 44° 20′ of the new diviſion: after the earthquake it was 43° 35′; the needle made 229 oſcillations in the courſe of ten minutes.

Experiments have proved that the magnetic charge has changed in this part of the world, and not in the needle.

At Calabozo, in the centre of Uana, lat. 8° 56′ 56″, long. from Paris 44° 40′ 18″, the inclination was 39° 30′: number of oſcillations 222.

At Atures, one of the cataracts of the Orenoquo, in lat. 5° 39′, long. 44° 42′ 19″, the inclination was 32° 85′: number of oſcillations 221.

At St. Fernando d’Atabapo, a miſſion at the mouth of the Guaviara, lat. 4° 9′ 50″, the inclination was 30° 30′: number of oſcillations 219.

At St.

Carlos de Rio Negro, lat. 1° 53′, the inclination was 23° 20: number of oſcillations 216.

According to the rules given by Meſſrs. Cavendiſh and Dalrymple, care was always taken, while obſerving, to turn the compaſs to the eaſt and weſt to find the mean inclinations, and to correct the error which takes place when the axis of the needle does not paſs exactly through its two points.

During this journey, which laſted a year, I determined 54 points of South America, in which I obſerved the latitudes and longitudes: the former deduced, for the moſt part, from the meridian altitude of two ſtars at leaſt; and the latter, either from the diſtances of the moon from the ſun and ſtars, or from the time-keeper and horary angles.

I am now employed in conſtructing a map of the country through which I have travelled; and as my obſervations fill up the vacuum found in the maps between Quito and Cayenne, to the north of the river of the Amazons, I flatter myſelf that they will be intereſting to geographers.

My time-keepers have not given me with exactneſs, but the differences of meridian between the places of my departure and the Caraccas, Cumana, and St. Thomas de Nueva-Guayanna, lat. 8° 8′ 24″, long. 21 of time, eaſt from Cumana. I am very anxious, therefore, on account of my map, to fix the poſition of theſe three places in regard to Paris, and by obſervations purely aſtronomical.

Beſides, it is very neceſſary that navigators ſhould be able, at the time of their arrival on this coaſt, to find the longitude of the ports well determined, that they may know the ſtate of their chronometers; for, except Martinico, Guadaloupe, Portorico, where M. De Churucca obſerved; Cayenne, and Quito, there are very few places the longitude of which can be depended on; eſpecially in Spaniſh America.

Carthagena, according to the Connoiſſance des Temps, is at 5 h. 12′ 12″.

But the three emerſions of the ſatellites, obſerved by Herrera, all give 69° 24′ 10″ weſt of Cadiz, or 5 h. 13′ 11″ to the weſt of Paris.

I obſerved, with a teleſcope of Dollond, which magnifies 95 times, at Cumana, in lat. 10° 27′ 37″:

The immerſion of the ſecond ſatellite Nov. 7, 1799, at 11 h. 41′ 18′ true time.

Of the ſecond ſatellite, Sept. 11, at 16 h. 31′ 0″ true time.

Of the firſt ſatellite, Sept. 25, 1800, at 17 h. 10′ 21″ mean time.

The emerſion of the 4th ſatellite, Sept. 26, at 17 h. 28′ 0″ mean time.

Of the third ſatellite, Sept. 27, at 16 h. 25′ 55″ mean time.

Of the fourth ſatellite, Sept. 26, at 17 h. 28′ 0″ mean time.

I am therefore miſtruſtful of the longitude of Cumana, as given me by my time-keeper.

When I arrived from the Canaries at the Continent, I found the longitude to be 4 h. 26′ 4″; and the obſervations of M. Fidalgo, who obſerved emerſions at Trinidad, but not at Cumana, give ſtill more; viz.

4 h. 26′ 16″.

Fidalgo found Trinidad 55° 16′ 32″ to the weſt of Cadiz, and Cumana 2° 41′ 25″ to the weſt of Puerta Eſpan̄a.

But the map of Trinidad, publiſhed at London, from the excellent obſervations of M. De Charucca, makes Puerta Eſpan̄a 61° 22′ weſt from London. I am of opinion, therefore, that, in conſtructing the map, the authors had before them the calculations by Lalande of the occultation of Aldebaran, obſerved at Porto Rico on the 21ſt of October 1793; for the capital of Porto Rico is by the time-keepers 4° 34 to the weſt of Puerta Eſpan̄a, calculating the longitude by that of Porto Rico 63° 48 15″; and for Cumana 66° 29′ 40″ to the weſt of Paris.

The five eclipſes of the ſatellites which I ſend you, muſt throw light on this ſubject; and, in my opinion, the longitude of Cumana will not be much beyond 4 h. 25′ 20″.

Unfortunately, the eclipſe of the ſun, which I completely obſerved on the 28th of September at Cumana, making the horns paſs along the horizontal and vertical wires, was not viſible in Europe. I obſerved the end at 8 h. 14′ 22″ mean time; the time certain to 1″ nearly, having taken correſponding heights the ſame day.

At Carras (Plaza della S. Trinidad) lat. 10° 31′ 4″, I obſerved:

The immerſion of the firſt ſatellite, Dec. 7, 1799, at 16 h. 11′ 57″ true time.

Of the third ſatellite, Dec. 7, at 17 h. 11′ 36″ true time.

The emerſion of the firſt ſatellite, Jan. 17, 1800, at 11 h. 14′ 8″ mean time.

Of the ſecond ſatellite, Jan. 28, at 7 h. 58′ 8″ mean time.

Of the fourth ſatellite, Jan. 18, at 8 h. 13′ 3′ mean time.

At the Valle del Tuy al Pic della Cocuiza, lat. 10° 17′ 23″.

The emerſion of the firſt ſatellite, Feb. 9, 1800, at 11 h. 26′ 57″ mean time.

Of the third ſatellite on the 10th of February, at 7 h. 58′ 50″ mean time.

But theſe laſt eclipſes were obſerved with a teleſcope of Caroché, which, though a very good one, magnifies only 58 times, not being able to carry along with me, to Rio-Negro, the large teleſcope by Dollond.

Declination of the magnetic needle at Cumana on the 27th of October 4° 13′ 45″; at Caraccas, 4° 38′ 45″; at Calabozo, 4° 54′ of the old diviſion.

The port of La Guayra is exactly 29″ in time weſt from Caraccas; and I hope that, by giving immerſions and emerſions, the meridian of Caraccas will be properly fixed.

I have deſcribed, with Bonpland, more than 1200 plants.

A letter from Haſpel-la-Chenaye, chemiſt at Guadaloupe, dated Jan. 5, ſtates, that M. Humboldt had ſet out for the Havannah, after having left with the agent of the government at Guadaloupe a box for the Inſtitute and two packets, one for Fourcroy and the other for Delambre.

As the box has not yet arrived, nor the packets addreſſed to Fourcroy, it is to be preſumed that the above letter is not that mentioned by Haſpella-Chenaye