materials which I could procure. and to discuss the differences of position which these heterogeneous materials every instant presented. We ought not to be surprised at the uncertainty which prevails in the geography of Mexico, when we consider the fetters which have arrested the progress of civilization, not only in the colonies, but also in the mother country; and especially when we consider the long peace enjoyed by these countries since the commencement of the sixteenth century. In Hindostan, the wars with Hyder Aily and Tippoo Sultan, the continual marches of armies, and the necessity of seeking the shortest communication, have singularly contributed to augment geographical information. And yet an accurate acquaintance with Hindostan, a country visited by the most active nations of Europe, does not extend farther back than thirty or forty years. I ought to have foreseen, that, notwithstanding the most assiduous labour during three or four months, I could only give a very imperfect map of Mexico, compared with the maps of the most civilized countries of Europe. This idea, however, did not discourage me. When I considered the advantages afforded me by my individual situation, I had to flatter myself that my work, notwithstanding the important faults which might disfigure it, would still be preferable to what has yet been offered to the public on the geography of New Spain.

It will be said, without doubt, that it is yet too soon to draw up general maps of a vast kingdom for which exact data are wanting. But, for the same reason we should, with the exception of he province of Quito and the United States, publish no map of the interior of continental America. For the same reason, also, we should not yet construct maps of many parts of Europe, of Spain for example, or Poland, countries in which, on surfaces of more than 1600 square leagues, there is not to be found a single place whose position has been fixed by astronomical means. It is not yet fifteen years since, in the centre of Germany there were hardly twenty places the longitude of which was determined with certainty to within a sixth or an eighth part of a degree.

In the part of New Spain situated to the north of the parallel of 24°, in the provinces called Internas (in New Mexico, in the government of Cohahuila, and in the intendancy of New Biscay) the geograp her is reduced to form combinations from the journals of routes. The sea being at a great distance from the most inhabited part of these countries, he has no means to connect together places situated in the interior of a vast continent, with points on the coast a little better known. Hence, beyond the city of Durango, we wander as it were in a desert, notwithstanding the show of manuscript maps. There are not more resources to be found than Major Rennel possessed for draw

ing up maps of the interior of Africa. It is otherwise in the part of Mexico contained between the ports of Acapulco and Vera Cruz, and between the capital of Mexico and the Real* of Guanaxuato. In this region, traversed by me from the month of March, 1803, to the month of February, 1804, a region the most cultivated and best inhabited of the kingdom, there are to be found a sufficient number of points of which the position is astronomically determined. It is to be wished that a traveller, versed in the practice of observations, and provided with a sextant, or a small repeating circle of reflection, a chronometer, an achromatic telescope and a portable barometer for measuring the height of mountains, should travel in three directions over the north of the kingdom of New Spain. Ile should direct his course, 1st. from the city of Guanaxuato to the presidio of Santa Fe, or to the village of Taos in New Mexico; 2d. from the mouth of the Rio del Norte, which pours its waters into the gulph of Mexico, to the sea of Cortez, particularly to the junction of the Rio Colorado and the Rio Gila; and, 3d. from the city of Mazatlan, in the province of Cinaloa, to the city of Alta Mira, on the left bank of the Rio de Panuco.

The first of these three journies would be the most important, the easiest to execute, and that in

*The word Real indicates a place where mines are worked.

which the chronometer would be exposed to the smallest changes of temperature. It would be useful, however, not to rely altogether on the mere lapse of time, but to employ for determining the longitudes, the satellites of Jupiter, eclipses, and especially the distances from the moon to the sun, means which since the publication of the excellent tables of Delambre, Zach, and Bürg, merit the highest degree of confidence. In the astronomical journey from Mexico to Taos, the position would be verified which I have assigned to St. Juan del Rio, to Queretaro, Zelaya, Salamanca, and Guanaxuato; the longitudes and latitudes would be determined of S. Luis Potosi, Charcas, Lacatecas, Fresnillo and Sombrerete, five places celebrated for the riches of their mines; and the passage would lie through the city of Durango and the Parral at Chihuahua, the residence of the governor of the Provincias Internas. In following the Rio Bravo, the traveller would pass along by the Passo del Norte, to the capital of New Mexico, and from thence to the village of Taos, the most northern point of this province.

The second journey, the most severe of all, and in which the observer is exposed to a burning climate, would supply fixed points in the new kingdom of Leon, in the province of Cohahuila, in New Biscay, and in Sonora. The operations should be directed from the mouth of the Rio Bravo del Norte, through the episcopal seat of

Monterey, to the presidio of Moncloya. Pursuing the route by which the Chevalier de Croix, viceroy of Mexico, arrived in 1778, in the pro vince of Texas, he would reach Chihuahua to connect the second journey with the first; from Chihuahua he would pass by the military establish. ment (presidio) of S. Buena Ventura, to the city of Arispe, and from thence, either by the presidio of Tubac, or by the missions of the Primeria alta, or across the savannahs inhabited by the Apaches tontos Indians, to the mouth of the Rio Gila.

The third excursion, in which he would traverse the kingdom from Alta Mira to the port of Mazatlan, would be connected with the first by the city of Sombrerete; it would serve, by a winding to the north, to fix the position of the famous mines of Catorce, of Guarisamey, Rosario and Copala. A few days would suffice to determine the latitude and longitude of every place we have named. Only the most considerable cities, such as Zacatecas, S. Luis Potosi, Monterey, Durango, Chihuahua, Arispe, and Santa Fe of New Mexico, would occasion a stay of a few weeks. The astronomical means here indicated easily afford, although the observer should not possess a very extraordinary ability, a certainty of 20 seconds for the latitude, and of a third of a minute

*

* One of our most celebrated astronomers observes with truth, that even at this day, since the introduction of repeating