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this circumstance gives somewhat more confidence in the medium result.

Chihuahua.-Latitude, 29° 11' according to Rivera, 28° 45′ according to Mascaro. Longitude deduced from the rhombs and distances, 5° 25' to the west of Mexico.

Santa Fe.-Latitude, 36° 28′ by Rivera, 36° 10' by Lafora. Longitude by approximation, 5° 48′ in relation to the meridian of Mexico.

Presidio de Janos.-Latitude, 31° 30′ by Rivera, 30° 50' by Mascaro. Longitude, somewhat doubtful, 7° 40' to the west of Mexico.

Arispe.-Latitude, 30° 30' by Rivera, 30° 36' by Mascaro. Longitude by approximation, 9° 58' (from Mexico).

Geographical combinations founded on itineraries give an additional probability to the following positions, of which MM. Mascaro and Rivera determined the latitude. These results, adopted in my map, agree with what was obtained by MM. Bausa and Antillon. We differ, however, nearly a degree in the absolute longitude of Arispe, a city situated in the province of Sonora, as well as in the longitude of the Passo del Norte, in New Mexico. But I have to repeat, that a part of these differences arises from M. Antillon's placing in his map Mexico, Acapulco, and the mouth of Rio Gila more to the eastward than I have done.

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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 Oaxaca, 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 altitudes taken with gnomons. The map 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

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In la Misteca alta the position has been determined of

S. Antonio de las Cues at 18° 3′ of latitude.

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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 latitude was astronomically determined. What gives us a certain degree of reliance 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° 22′, 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 im

perfectly 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 Fish-Bay. 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 several points from the excellent observations of M. Ferrer, already cited. This able observer, having placed the port of Vera Cruz g′ 45′′ less to the west than is done by I have reduced the positions of the places determined by him in the environs of Vera 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

me,

* Carta esferica que comprehende las costas del Seno Mexicano, construida en el Deposito Hidrografico de Madrid, 1799.

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