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Spanish operations. I have reason to believe that the absolute positions laid down by us for Acapulco, S. Blas, and Cape Lucas, are sufficiently correct, and that the error of + 28' en arc exists farther to the north. A false supposition in the diurnal course of a chronometer, and the state of the old lunar tables of Mayer and Mason, may have contributed to this error.

After discussing the positions which are founded on astronomical observations by experienced observers, I pass to those which may be regarded as doubtful, on account of the imperfection of the instruments, the want of confidence which the names of the observers inspire, and of our ignorance whether the results have not been drawn from manuscripts inaccurately copied. What follows is the substance of what I have been able to collect from these astronomical observations: they must be employed with caution; but they are valuable for the geography of a region hitherto so little known.

The Jesuits are entitled to the praise of having been the first who examined the gulf of California or the sea of Cortez. Father Kin, formerly professor of mathematics at Ingolstadt, and the declared enemy of the Mexican geometrician Siguenza, against whom he composed several writings, arrived in 1701 at the junction of the great rivers Gila and Colorado. He fixed by an astronomical ring the latitude of this junction at

35° 30. I see from a manuscript map drawn up in 1541 by Domingo de Castillo, found in the archives of the family of Cortez, that at this epoqua two rivers were already known, which appeared to unite under the latitude of 33° 40′, and were called Rio de Buena, Guia, and Brazo de Miraflores. Three years before, in 1538, Father Pedro Nadal found by the meridian altitude of the sun, the junction of the Gila and Colorado, 35° 0'. Fray Marcos de Niza made it 34° 30'. It was undoubtedly on these grounds. that Delisle adopted 34° in his maps: but in a work printed at Mexico*, recent observations are cited, made by means of an astronomical ring by two well instructed fathers of St. Francis, Fray Juan Diaz, and Fray Pedro Font; observations which agree with one another, and which would seem to prove that the junctions are much more southern than has hitherto been believed. In 1774, Father Diaz obtained at the mouth of the Gila, two days successively, 32° 44'. Father Font found there, in 1775, 32° 47'. The former asserts also, that from a simple consideration of the road followed by him, that is to say, a consideration of the rhombs and distances, it is impossible that the junctions can be at 35 of latitude. The positions which Father Font assigned in 1777 to the missions of Monterey, S. Diego, and S. Francisco, and which differ but a few mi

* Cronica Serafica de Queretaro, p. 11, 1792, Prologo.

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° 37′, 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 errors are sometimes +1°11', sometimes-25'. It is true the English navigator did not himself visit these three missions, but he connected them with the neighbouring coast, the situation of which he examined. From hence may be 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 33° 30'. 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†.

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 provincias internas; and the ma

* In the original, de la quelle ils passèrent de la Tarahumara à Colhuacan. Translator.

+ 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. 47, No. 55).

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 indi cated, 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 10' in the latitude of that city; but my

* 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.

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