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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 59', from whence there results a difference of longitude between 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° 9'; 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
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, go 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 La
* Analysis de los fundamentos de la Carta de la America septentrional.
guna, not by astronomical rings, or hy gnomons, but by means of several quadrants of from ihree 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 lati. u e to be 22° 5'6". These observatious 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 believid 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 Za. catecas 4° 3' to the west of Me ico; but this result is probably very false. Afior fixing the position of Guanaxuata by the chronometer, and by lunar distances, I deduced from rhombs and estimated itinerary distinci's, a difference of meridians of 2° 32'. The calculations of M. Mascaro's itinerary gile go 45'. As to the ab. solute longitude, the cou: t fixes it in a manner equally erroneous. He pretends to have concluded from a corresponding ob ervation of an eclipse at Bologna, that Zacatecas is 7h 13' 50" to the west of that city, which would give 71 13' 59" of longitude for Zacatecas, and con-equently 7h 8' 39" (in place of 6' 45' 42") for Mexico. Can
an error have glided into the figures ? Perhaps the difference of meridians is 7h 30' in place of
The longitude of Durango should be very nearly 105° 55'. Don Juan Jose Oteyza, a young Mexican geometrician, the benefit of whose abi. lities I have often experienced in the course of my operation,' observed there (at l'Hacienda del Ojo, 38' to the east of Durango) the termination of an eclipse of the moon, which, compared with the old tables of Mayer, gave the result which we have already indicated. The author even did not consider it as completely accurate. M. Friesen concluded from the rhombs and distances indicated in the itineraries of Brigadier Rivera and M. Mascaro, that this longitude was 5° 5' to the east of Mexico, consequently 106° 30'. The latitude of Durango appears sufficiently doubtful. Rivera and his companion Don Francisco Alvarez Bareiro pretend to have found it, by meridian altitudes of the sun, 24° 38'; Lafora, in 1766, 24° 9'; but we do not know what instruments these engineers made use of. If the latitude which the Count de la Laguna, M. Zarria, and the engineer Mascaro assign to the city of Zacatecas is exact, that of Durango, deduced from the rhombs and distances, should be nearly 24° 25'.
There are several places in the northern provinces of New Spain, where the three engineers already cited made observations successively; 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, 5o 25' to the west of Mexico.
Santa Fe.-Latitude, 36° 28' by Rivera, 360 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, go 53' (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.