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nutes from the result of Vancouver and Malaspina's observations, would seem to testify in favour of the accuracy of his labours, provided these fathers did not copy the data furnished to them by their pilots. Besides it is certain that a zealous observer may, with very imperfect means, procure often very satisfactory results. The latitudes obtained by Bouger in the Rio de la Magdalena, with a gnomon from seven to eight feet in height, and employing for a scale pieces of reeds, differ only from four to five minutes from what I found fifty-nine years afterwards by means of excellent English sextants.
However, Father Font appears to have been less fortunate with his astronomical ring in fixing the latitude of the mission of S. Gabriel at 32° 31*, that of S. Antonio de los Robles at 36° 2', and that of Luis Obispo at 35 17'. Comparing these positions with the atlas of Vancouver, I find that the errorsaresometimes + 1° 1 l',sometimes—23'. It is true the English navigator did not himself visit these three missions, but he connected them with theneighbouringcoast,thesituationof which heexamined. From hence maybe seen how much we ought to be on our guard against observations made with astronomical rings. Fray Pedro Font visited also the site of the ruins called las Casas grandes; and he found them 338 3O'. This position, were it exact, would be very important; for it is the site of an ancient cultivation of the human species. We must not, however, confound this second abode of the Azteques from which they passed from Tarahumara to Colhuacan*, with the Casas grandes,or the third abode of the Azteques, situated to the south of the presidio of Yanos, in the intendancy of New Biscay. I could wish to know the observations of the Jesuit Father Juan Hugarte, who discovered, according to M. Antillon, the errors in the maps of California. He is even said to have first discovered that this vast country was a peninsula; but in the sixteenth century nobody in Mexico denied this fact, which was long afterwards doubted in Europe f.
I reckon among the operations somewhat doubtful, those which were executed by several Spanish engineer officers in the frequent and laborious visits which they made to the small forts situated on the northern frontiers of New Spain. I procured at Mexico the itineraries of brigadier Don Pedro de Rivera, drawn up in 1724; those of Don Nicholas Lafora, who accompanied the Marquis de Rubi in his researches, in 1765, as to a line of defence for the provmcias internas; and the ma. nuscript 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 \<y in the latitude of that city ; but my result being founded on a method analogous to Douvves', 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'. MM. Bauza and Antillon, by a union of ingenious combinations, and by connecting S. Fe with the Presidio de 1'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 BrigadierRibera. The distances and rhombs gave me by graphical construction the difference of the meridians of Durango and Chihuahua53', from whence there results a difference of longitude between Mexico and SantaFe 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
* In the original, de la quelle ils passerent de la Tarahumara H Colhuacan. Translator.
f In 1539, Francisco de Ulloa, in an expedition undertaken at the expense of Cortez, explored the gulf of California to the mouths of the Rio Colorado. The idea of California's being an island has its date only in the seventeenth century. (Antillon, Analysis, p. A7» No. 55).
* l. 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 d 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 desdo Arispe a Mexico en 1785. The originals of these eight manuscripts are preserved in the archives of the viceroyalty of Mexico. •