4(51 



which I made at the mission of Esmeralda, is in 



3° 10' of north latitude, and 68° 37' of longi- 



Great Cataracts and the mouth of the Apure, and as the 

 daily loss was extremely uniform (between San Fernando de 

 Atabapo and Maypures, at 24° and 29° cf temperature, 

 28*5" ; between San Fernando de Atabapo, the Rio Negro, 

 the Cassiquiare, and Esmeralda, from 22° to 24° of tempera- 

 ture, 27*9"), the central point of Esmeralda may be consi- 

 dered as sufficiently well determined. This may be relied on 

 with more confidence, as my cbronomstric longitudes of the 

 interior rest on those of Camas* and Caraccas, two pomts of 

 the coast where I had observations of the satellites of Jupiter, 

 lunar distances, and an eclipse of the Sun. The positions of 

 the maps which appeared before the publication of my obser- 

 vations of the Oroonoko err by excess toward the east and 

 the south. D'Anville alone, by a happy tact, saw better 

 than those who have followed him. As geographers hereto- 

 fore differed much in the absolute longitudes, which they as- 

 signed to the points of land-fall (at Barbadoes, the island of 

 Trinidad, or at Cumana), I have reduced, in the following 

 table, the longitudes to the meridian of the Castle of Saint 

 Antonio at Cumana : 



Esmeralda. 



W. lat. 3° 11' long. 1° 53' from astronomical obserr, 



W. 1 58 2 19 D'Anville. 



E. 3 40 0 15 La Cruz Olmedilla. 



E. 3 38 0 18 Surville and Caulin. 



E. 3 28 0 8 Faden. 



W. 3 38 0 8 Buache. 



The Spanish maps, constructed from the materials furnished 

 by the expedition of Solano, admit 3° 44' for the difference 

 of meridians between Esmeralda and San Fernando de Ataba- 

 po ; but it is only 2" 7'. These same maps place Esmeralda 



