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inferior to those of Velasquez and Gama, two of his counttyinen, whose true merit has never been sufficiently known in Europe. Don Josef Antonio Alzate, and Ramirez in his map of New Spain, published at Paris, place Mexico at 104° 9' 0' 65 56' 36". M. de Lalande finds, by the transit of Venus observed in 1769 by Alzate, 6h 50'1": M. Pingre finds 61 49 43'. An eclipse of the moon, observed in 1769 by Alzate, gives, calcu. lating only the end by the old lunar tables, 6 37 . Cassini deduces from two emersions of Jupiter's satellites, observed by Alzate in 1770, and compared with the old tables by a medium, 101° 25'-6" 45' 9"..
In a memoir published by Alzate on the geography of New Spain *, he asserts that the longitude of Mexico, founded on observations of satellites, is 646' 30".
But in 1786, in a note which accompanies the plan of the environs of Mexico, drawn up by Seguenza, and engraved at Mexico, Alzate fixes the longitude at 100° 30' 0"=61 42' 0”, adding that this last result, the surest of all, is founded on more than twenty-five eclipses of satellites communicated to the academy of Parist.
Hence there is consequently a difference of
* Gazetta de Mexico, 1772, No. 95, p. 56.
+ Plano de les Arcanias de Mexico por Don Carlos de Se. guenza, reimpreso en 1786, con algunas adiciones de Don Josef Alzate (en la imprenta de Don Francisco Rangel.)
more than two degrees between the different ob. servations of M. Alzate, without including the result deduced from the eclipse of the moon of the 12th December, 1769. It is to be presumed that the observer was not exact as to the time. The longitude established by the satellites may be also too eastern, because the eclipses of the first satel. lite have not been separated from those of the third and fourth.
The false position so long attributed to the capital of New Spain produced a remarkable effect at the time of the sun's eclipse, 21st Feb. 1803. The eclipse was total, and threw the public into consternation, because the almanacs of Mexico, calculated on the supposition of 61 49 43" of longitude, had announced it as scarcely visible. The learned astronomer of the Havannah, Don Antonio Roberedo, recalculated this eclipse according to my observations of longitude *. He found that the eclipse would not have been total if the longitude of Mexico were farther west than 65 46' 35", 4=101° 38' 49".
The latitude of the capital of Mexico remained for a long period as problematical as its longitude. In the time of Cortez the Spanish pilots fixed it at 20° 0', as is proved by the map of California, drawn up by Domingo de Castillo in 1541, and
* Aurora, or Correo politico economico de la Hayana, 1804, No. 219, p. 13.
published in the Mexican edition of Cortez's letters*. This latitude was preserved by d'Anville and other geographers. Jean Covens, who increased the longitude of Mexico seven degrees, gives it also a position too northern by 1° 43'. The account of Chappe's journey adopts from Alzate 19° 54' of latitude. Don Vincente Doz, known for his observations in California, found by a quadrant 19° 21' 2"+; but in the year 1778, Velasquez and Gama fixed the true position. Don Jose Espinosa found in February 1790, by a sextant of eight inches radius, the cathedral 19° 25' 25' of latitude. M. Galeano obtained in 1791, by larger instruments, 199 26' 00“.
Latitude, 19° 11' 52". Longitude, 6h 33' 56" =98° 29'0". This longitude is deduced from a stellar eclipse, observed by M. Ferrer, and calculated by M. Oltmanns, from three eclipses of the first satellite, and from the longitude which my observations assign to the Havannah, and which has been connected by the transference of time to Vera Cruz. It is to be observed, that I indicate
* Historia de Nueva España escrita por Herman Cortes, aumentada por el Illustr. Señor Don Francisco Antonio de Lorenzana. Mexico, 1770, p. 328.
t Gazetta de Mexico, 1772, p. 56.
the position of the most northern part of the city, the observatory of M. Ferrer being the house of Don Jose Ignacio de la Torre, which is 30" to the west of the fort of St. Juan d’Ulua.
This longitude is almost the same with what was found by Don Mariana Isasvirivil, and by other officers of the Spanish marine. It is only five minutes en arc farther west than what is indicated on the map of the gulf of Mexico, published in 1799 by the hydrographical board of Madrid. M. Antillon fixes it at 98° 23' 5"; the Knowledge of Times for the year 1808, at 98° 21' 45'. Don Thomas Ugarte, commodore (Chef d'Es. cadre) in the service of the king of Spain, connected by the transference of time Vera Cruz with Porto Rico. He assigns to the first port 98° 39' 45". M. Ferrer deduced in 1791 and 1792 the longitude of Vera Cruz from sixty series of distances from the moon to the sun and stars : he obtained as a middle term, 90° 18' 15". But it would be exceedingly interesting to publish a detail of these observations, that they might be recalculated according to the tables of Bürg. The same observation applies to the results published in Vancouver's voyage.
The city of Vera Cruz has shared the same fate with Mexico and the whole of the new continent. They have been believed 60, nay even 140 leagues farther distant from Europe than they are in reality. Jean Covens placed Vera Cruz at 104° 45'0"; Alzate, in his map of New Spain, at 101° 30'.
M. Bonne * justly complains of the want of agree. ment among the astronomical observations at Vera Cruz. After a long discussion he fixes on 99° 37'. This is nearly the same longitude which d'Anville and the French Neptune adopted, and it is that to which the English astronomers have long given the preference. The tables of Hamilton Moore indicate 99° 49' 47" ; but Arrowsmith (map of the Spanish possessions, 1803) makes it 98° 40', and nine years before, Mr. Thomas Jeffreys, geographer to the king of England, 100° 23' 47".
If formerly the prevailing error was the assigning too great western longitudes to the American ports, the Abbé Chappe fell into the contrary extreme: he deduced from his chronometer the longitude of 97° 18' 15't. If this observer, who possessed more zeal than accuracy, could have, taken the distances from the moon to the sun, he would have perceived the error of more than a . degree, into which he had been induced by an excess of confidence in his chronometer. i .. The oldest astronomical observation at Vera Cruz (at the chateau St. Juan de Ulua) is undoubtedly that of the moon's eclipse in 1577. Comparing the end of that eclipse with a corresponding observation at Madrid, M. Oltmanns
* Atlas pour l'ouvrage de l'Abbé Raynal, p. 11.