253 



precision ; we do not know whether sloops can 

 ascend to this point. 



After the lake of Nicaragua, Cupica, and 

 Huasacualco, the isthmus of Panama merits 

 the most serious attention. The practicability 

 of forming a canal for ship navigation depends, 

 at the same time, on the height of the point of 

 partition, and the configuration of the coasts; 

 that is, on the maximum of their nearness to 

 each other. So narrow a neck of land might, 

 by its direction, have escaped the destructive 

 influence of the current of rotation; and the 

 supposition that the greatest height of the 

 mountains must correspond to the minimum of 

 the distance between the coasts, would not, in 

 our days, be justified even by the principles of 

 merely systematic geology. Since I published 

 my first work on the junction of the seas, we 

 remain, unfortunately, in the same ignorance 

 respecting the height of the ridge which the 

 canal must pass over. Two learned travellers, 

 MM. Boussingault and Rivero, levelled the 

 Cordilleras from Caraccas to Pamplona, and 

 from thence to Santa-Fe de Bogota, with a pre- 

 cision superior to any thing I could attempt in 

 that kind of research ; but on the north-west of 

 Bogota, from the Andes of Quindiu and Anti- 

 oquia, levelled by M. Restrepo and myself, as 

 far as the table land of Mexico, in the 12° of 

 latitude of central America, not one single mea- 



