148 



longitude *, may, on frontiers of 300 leagues, enlarge or 

 diminish the surfaces of new states to the extent of 12,000 

 square leagues ; but much more important differences arise 

 from lines of demarcation drawn somewhat arbitrarily be- 

 tween the lands that are regularly inhabited, and those that 

 are desert, or the dwellings of savage tribes. The limits of 

 civilization are more difficult to trace than political limits. 

 Little missions governed by monks are dispersed along a 

 river ; they may be termed the outposts of European civil- 

 ization, and, ranged in narrow and winding lands, advance 



* T estimate the errors of relative longitudes only, for in- 

 stance, the differences of longitude between the coast, and 

 the valley of the Rio Mamore, or of the Upper Javari. I 

 do not speak of the errors of absolute longitude, which some- 

 times exceed 3° or 4°, without influencing the measure of 

 surfaces. The longitude of the city of Quito ascertained by 

 me (81o 5' 30" west of Paris) has caused a considerable 

 change of the western part of America, in the most recent 

 maps. This differs 0° 50 f 30", from the longitude adopted 

 till my return to Europe (Connoiss. des Temps pour Vannee 

 1808, p, 236). The breadth of South America, between 

 Cayenne and Quito, according to d' Anville, is 30 nautical 

 leagues too little. It is the inequality of partial displace- 

 ments, that occasions the errors of relative longitude which 

 alter the calculation of the area. La Cruz Olmedilla, whose 

 great map has been successively copied and disfigured, placed 

 Santa Fe de Bogota half a degree too far to the east - 7 San 

 Carlos del Rio Negro 2J° $ and the mouth of the Apure a 

 quarter of a degree. The distance of Cumana fromjhe 

 mission of Esmeralda on the Upper Oroonoko, is estimated 

 by La Cruz 2|° too little. In general, before my voyage, 

 the whole system of the rivers Oroonoko and Rio Negro 

 was placed from 1° to lj° of latitude too far south, and 

 2° of longitude too far east. 



