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script travels of the engineer Don Manual Mascaro from Mexico to Chihuahua and Arispe". These respectable travellers assure us, that they made observations of the meridian altitude of the sun. I know not what instruments they made use of; and it is to be feared that the manuscripts which came into my hands are not always exactly copied; for having taken the trouble to calculate the latitudes by the rhombs and distances indicated, I found results which coincided very ill with the latitudes observed. MM. Bauza and Antillon at Madrid made the same observation. I regret that none of the observations of latitude of the engineer officers are connected with places whose position has been determined by M. Ferrer or myself. M. Mascaro indeed observed at Queretaro. We differ lo' in the latitude of that city; but my result being founded on a method analogous to Douwes’, is doubtful to nearly the extent of 2. Notwithstanding these uncertainties, the materials which I have spoken are of great use to those who would draw up maps of a part of the world so little visited by people of information. We shall content ourselves with discussing some of the most important points. Mr. Jefferson in his classical work on Virginia has discussed the position of the Presidio de S. Fe in New Mexico; he believes it to lie in 38° 10' of latitude; but striking a medium between the direct observations of M. Lafora and Fathers Velez and Escalante, we shall find 36° 12'. M.M. Bauza and Antillon, by a union of ingenious combinations, and by connecting S. Fe with the Presidio de l'Altar, and this again with the coast of Sonora, found S. Fe de Nueva Mexico 4° 21' to the west of the capital of Mexico”. The map of M. Antillon gives five degrees of difference. Without possessing any knowledge of the labours of these Spanish geographers, I arrived, by a different way, at a still greater result. I fixed the longitude of Durango by a lunar eclipse observed by Doctor Oteyza; this position agrees with the one adopted by M. Antillon; now, supposing the latitude of Durango 24°30', and that of Chihuahua, the capital of New Biscay, where M. Mascaro observed for a long time, 28° 45', I have thus been able to estimate the value of the leagues indicated in the Itinerary of Brigadier Ribera. The distances and rhombs gave me by graphical construction the difference of the meridians of Durango and Chihuahua 53, from whence there results a difference of longitudebetween Mexico and Santa Fe of 5°48'. It is natural enough that this difference should appear greater than what is indicated by MM. Bauza and Antillon, for these estimable geographers place the capital of Mexico 37 en arc too far to the west. The position assigned by them to Santa Fe depends, however, more on the longitudes of S. Blas and Acapulco than on that of Mexico. I found Santa Fe at 107° 13' of absolute longitude, MM. Bauza and Antillon at 107° 2'; a longitude extremely probable, but 5°28' more eastern than what is to be found in the map of west Louisiana published at Philadelphia in 1803. The same map is nearly four degrees false in the position of Cape Mendocino, notwithstanding the observations of Vancouver and the Spaniards. On the other hand, M. Costanzo concluded from a great number of combinations, that Santa Fe and Chihuahua were 4° 57 and Arispe 9° 5' to the west of Mexico. In all the old manuscript maps which I have consulted, particularly in those constructed since the return of M. Velasquez from California, Durango is placed three degrees to the east of the Parral and of Chihuahua. Velas

* 1. Derotero del Brigadier Don Pedro de Rivera en la visita que hizo de los Presidios de las Fronteras de Nueva España en 1724.—2. Itinerario del mismo autor de Zacatecas a la Nueva Biscaya.-3. Itinerario del mismo autor desde el Presidio del Paso del Norte hasta el de Janos.—4. Diaria de Don Nicolas de Lafora en su Viage a las Provincias Internas en 1766.-5. Derotero del mismo autor de la villa de Chihuahua al Presidio del Paso del Norte.—6. Derotero de Mexico a Chihuahua por el Yngeniero Don Manuel Mascaro en 1778. –7. Derotero del mismo autor desde Chihuahua a Arispe Mission de Sonora—8. Derotero del mismo autor desde Arispe a Mexico en 1785. The originals of these eight manuscripts are preserved in the archives of the viceroyalty of Mexico.

* Analysis de la Carta, p. 44.

quez reduced this difference of meridians to an arc of three minutes; but a graphical method, founded on itineraries, gives me 50'. I was equally well pleased to see that on another point of the geography of New Spain, my combinations conducted me to the same result that had been obtained by the learned astronomers of Madrid. My map constructed at Mexico, the same year in which M. Antillon published his Analytical Memoir”, indicates, as is proved by the copies deposited in Mexico, the difference of meridians of Tampico and Mazatlan, (that is to say, the breadth of the kingdom from the Atlantic ocean to the South Sea, to be 8° 0'. MM. Bausa and Antillon found it 8° 20', while the map of Lafora gives 17° 45', and that of the West Indies by Arrowsmith, 9° 1'. In my map I have connected Tampico with the Bar de Santander, of which the longitude was observed by M. Ferrer, supposing, agreeably to the maps of the marine depot of Madrid, Tampico 10' east of the Bar. We shall return in the sequel to the position of this port. The latitude of the city of Zacatecas, celebrated for the great wealth of its mines, was determined by the Count de Santiago de la Laguna, not by astronomical rings, or by gnomons, but by means of several quadrants of from three to four feet radius, constructed in the country itself: it was found 23° 0'. Don Francisco Xavier de Zarria concluded, from various gnomical observations, the latioude to be 22°5'6". These observations are to be found in a work almost unknown in Europe, the Chronicle published by the fathers of S. Francis of Queretaro at Mexico. Zacatecas was formerly believed half a degree farther north, as is proved by a small Table of Latitude, published at Mexico, by Don Diego Guadalaxara, for the use of those desirous of constructing gnomons. The Count de la Laguna asserts, that he found the longitude of Zacatecas 4° 3’ to the west of Mexico; but this result is probably very false. After fixing the position of Guanaxuata by the chronometer, and by lunar distances, I deduced from rhombs and estimated itinerary distances, a difference of meridians of 2° 32'. The calculations of M. Mascaro's itinerary give 8° 45'. As to the absolute longitude, the count fixes it in a manner equally erroneous. IHe pretends to have concluded from a corresponding observation of an eclipse at Bologna, that Zacatecas is 7" 13' 50" to the west of that city, which would give 7, 13° 59' of longitude for Zacatecas, and consequently 7" 3' 39" (in place of 6" 45'42") for Mexico, Can

* Analysis de los fundamentos de la Carta de la America septentrional.


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