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On the formation of militia (tropas de milicia) in the kingdom of New Spain, there was drawn up a map of the province of Quaucu, in which several places are found marked whose latitude (according to a remark of the author) had been observed astronomically. I do not know if these latitudes are founded on meridian altiuie taken with gnomons. The man bears the name of M. Don Pedro de Laguna, lieutenant-colonel in the service of his Catholic majesty. These eleven
points are partly situated on the coast between the two ports of Acapulco and Tehuantepec, partly near the coast in the interior of the country. Proceeding from west to east we find
In la Misteca alta the position has been determined of
S. Antonio de las Cues at 18° 3' of latitude.
We may add the village of Acatlan in the intendancy of la Puebla at 17° 58', and the city of Oaxaca at 16° 54' of latitude. These determinations, if they have any degree of accuracy, are so much the more precious, that from la Puebla de
los Angeles to the isthmus of Panama, there was not hitherto a single point in the interior of the country whose latitu le was astronomically determined. What gives us a certain degree of reli. ance on these positions, is the harmony which prevails between the latitudes assigned in the map of Don Pedro Laguna and in those of M. Antillon, to the city of Tehuantepec and to Puerto Escondido. Hence the Spanish navigators at present place the former port at 16° 24', and the latter, which is in the neighbourhood of the village of Manialtepec, at 15° 50' of latitude.
Hitherto we have discussed positions founded on astronomical observations, more or less worthy of the geographer's confidence; there remains for us to indicate the maps, almost wholly manuscript, which we have employed for the different ports of the general map of New Spain.
As to the bearings and sinuosities of the western coast washed by the great ocean, from the port of Acapulco to the mouth of the Rio Colorado, and to the volcanos of the Virgins in California, I have followed the map which accompanies the account of the voyage of the Spanish navigators to the Straits of Fuca. This map, published in 1802 by the marine depot at Madrid, is founded on the operations of the corvettes of Malaspina; but the coast which stretches to the south-east of Acapulco is still very imperfectly known. The map of North
America by M. Antillon was consulted in its construction. There is ground for complaint against the inaccuracy with which the eastern coast of Mexico to the north of Vera Cruz has been hitherto surveyed. The part contained between the mouths of the Rio Bravo del Norte and the Mississipi is almost as little known as the eastern coast of Africa between Orange River and FishBay. The expedition of MM. Cevallos and Herera, provided with superb astronomical instruments, is engaged in taking exact plans of those desert and arid regions. Meanwhile I have followed, for the detail of the eastern coast, the map* of the gulph of Mexico, published by order of the king of Spain in 1799, and retouched in 1803. I have however corrected sereral points from the excellent observations of M. Ferrer, already cited. This able observer, having placed the port of Vera Cruz 9' 45' less to the west than is done by me, I have reduced the positions of the places determined by hin in the environs of Vira Cruz, to the longitude resulting from the calculations of . M. Oltmanns. The error of the old maps consisted especially in the longitude of the Bar of Santander, which, according to M. Ferrer, is 1° 45' 15" to the west of Vera Cruz, while the map of
* Carta esferica que comprehende las costas del Seno Mexicano, construida en el Deposito Hidrografico de Madrid, 1799.
the Deposito admits 1° 23' of difference of longitude. I have constantly followed the observations of M. Ferrer, in reducing the longitude of Ta. nuagua on that of Santander.
The territory comprised between the ports of Acapulco and Vera Cruz, between Mexico, Guana uata, the valley of Santiago and Valladolid, between the voicano of Jorullo and the Sierra de Toluco, is constructed from a great number of geodical surveys, taken by me either with a sextant or the graphometer of Adams. The part contained between Vlexico, Zacatecas, Fresnillo, Som. brerete, and Durango, is founded on a manuscript plan which V. Oteyza had the goodness to construct for me, from materials collected by him in his journey to Durango. Having marked with great exactness the rhombs and the distances estimated from the pace of the mules, his plan merits undoubtedly some confidence, particularly as the positions of Guanaxuata and S. Juan de Rio were corrected by direct observations of my own, independent of one another. By this means it became easy to convert time into distance, and to ascertain the value of the leagues of the country.
The journals of MM. Rivera, Lafora, and Mascaro, which we have already cited, were of assistance for the provincias internas, particularly for the routes from Durango to Chihuahua, and from thence to Santa Fe and Arispe in the province of Sonora. However, these materials could only be