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The difference of longitude between the port and the capital is marked 2° 29' instead of 3° 38' as in the map of Arrowsmith, and instead of 2° 56 30“ the result of my astronomical observations. It is also very improbable that the Volcano of Tlascala indicated in this new English map, is the Sierra de Tlascala, called in the country Malinche; for this Sierra is neither very remarkable for its elevation, nor very distant from la Puebla. This confusion is so much the more astonishing, as in 1803 the excellent observations of Don Jose Joacquin Ferrer, published in 1798, were known in London*, as well as the maps drawn up by the Deposito Hydrografico of Madrid ; though even M. Antillon places it in 1802, in his map of North America, la Puebla 32' too much to the south.

* Ephemerides geographiques de M. de Zach, 1798, T. II. p. 393. It is from this map that I cite the results obtained by M. Ferrer. They sometimes differ from those indicated in the manuscripts, which that excellent and indefatigable observer had, probably from less careful calculations, drawn up upon the spot, of which I am in possession of copies. I am bound to make this observation for the sake of those, who, having procured copies of my works, may be astonished at finding numbers in them differing from those now published by me. It is only after calculating carefully every observation that we can arrive at exact results.



In two excursions which I made, the one to the mines of Moran and to the porphyretical summits(organos)of Actopan, the other to Guanaxuato and to the volcano of Jorullo in the kingdom of Mechoachan, I determined the position of ten points, whose longitudes are almost all founded on the transference of time. These points have enabled me to give with some accuracy a great part of the three intendancies of Mexico, Guanaxuato, and Valladolid. The longitude of the city of Guanaxuato was verified by distances from the moon to the sun. Its latitude, deduced from the observation of a de la Grue, is 21° 0' 9'. Fomachant gave me 21° 0' 28", and B de la Grue, 21° O'8". The Jesuits in their map, engraved at la Puebla in 1755, placed Guanaxuato at 22° 50' of latitude, and 112° 30' of longitude, an error of go! M. Velasquez, who observed the satellites of Jupiter at Guanaxuato, found this city 1° 48' to the east of Mexico, but at 20° 45' 0" of latitude, as is proved by his manuscript map of New Spain. This error of latitude is so much the more extraordinary, as the difference in longitude which it indicates is to within an arc of I', the same with what results from my


Latitude of Toluca by a de la Grue 19° 16' 24", by Fomahant, 19° 16' 3". I endeavoured as much as possible constantly to observe the same stars to diminish any error from the uncertainty of the declination.

The position of Nevado de Toluca, the latitude of Patequero, a city situated on the banks of the lake of the same name, of Salamanca, St. Juan del Rio, and Tisayuca, are founded on imperfect observations. There are circumstances in which the method of Douwes gives very inaccurate results; but in a country presenting so few fixed points we must often be contented with a simple approximation. I think I can venture to assert, that the longitudes of Queretaro, Salamanca, and San Juan del Rio, may be confidently relied on.

Even in the valley of Mexico there are several very important points, the position of which was determined by Velasquez, the celebrated Mexican geometrician of the eighteenth century. This indefatigable man executed in 1773 an extensive survey along with a trigonometrical operation, to prove that the waters of the lake of Tezcuco might be conducted to the canal of Huehuetoca. M. Oteiza was kind enough to calculate for me the triangles of Velasquez, of which I possess the manuscripts. M. Oltmanns went over the same calculations. He subjected the positions of the signals to the latitude and longitude which we have here adopted for the convent of St. Augustin in

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the capital of Mexico. These results of M. Oltmanns are contained in the table of geographical positions. No doubt can remain : s to the oblique distances; but the want of observations of azimuths gives a little uncertainty to the reduction of the perpendiculars or differences in latitude and longitude. We shall return to this subject in the analysis of the map of the environs of Mexico.

The seventeen positions fixed by M. Ferrer in the environs of Vera Cruz depend on the longitude of that port. That longitude having been supposed by me 10° 45' farther west than the Spanish astronomer indicates, I have reduced to the meridian of Paris the longitudes published by M. Ferrer, adding xo 47' 13"; for that observer calculated the lunar distances, from the Knowledge of Times, at an epoqua when Cadiz was believed to lie 8° 36' 30" to the west of Paris. I have for the same reason changed the absolute longitudes of Xalappa, the Cofre de Perotte, and the Pic d'Orizaba. M. Ferrer, for instance, places the latter at 90° 48' 29" of west longitude from Cadiz, while from the same meridian he fixes Vera Cruz at 89° 41' 45'.



The north-west part of New Spain, the coast of California, and of what the English call New Albion, contain many points determined by the

most exact geodesical and astronomical operations of Quadra, Galeano,and Vancouver. Few European charts are better established shan those of Western America, from Cape Mendocino to Queen Charlotte's Straits.

Cortez, after setting on foot two voyages of discovery in 1532, under Diego Hurtado de Mendoza, Diego Becerra, and Hernando de Griscalva, examined himself in 1533 the coast of California, and the gulf which has since very justly borne the name of the sea of Cortez*. In 1542 the intrepid Juan Rodriguez Cobrillo pushed as far north as 44° of latitude; the Sandwich Islands were discovered by Juan Gaëtan; and in 1582 Francisco Gali discovered the north-west coast of America under 57° 30' of latitude; so that long before the intrepid Cook made this part of the great ocean to be known, which cost him his life, the same regions had been visited by Spanish navigators. But very often the rapid promulgation of discoveries does not depend upon him who makes them. Yet the merit of a private citizen is indea pendent of the false policy of a government, which from an ignorance of its own interest would prevent a nation from enjoying the glory which it has earned. But this subject, equally delicate and interesting, has been treated with great discernment, in the historical introduction to the voyage

* Gomara Hist. cap. 12.

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