269 



seems to have traced the line of junction. The 

 navigable part is 17 leagues in length (20 to a 

 degree), of which there are only 6h of artificial 

 excavation ; the remainder forms a natural na- 

 vigation on the lakes of Oich and Lochy, sepa- 

 rated heretofore by a rocky ridge. This canal 

 was completed in the space of 16 years, admits 

 the passage of frigates of 32 guns, and of large 

 ships employed in foreign trade. Its mean 

 depth is 18 feet 8 inches (6 m ,09), and its breadth 

 at the bottom, 47 feet (15 m ,2). The locks, 23 

 in number, are 150 feet long, and 37 feet 

 wide. 



Being guided in the practical views presented 

 at the end of this chapter, only by the analogy 

 of the labours already performed by man, I 

 shall first observe, that the breadth of the isth- 

 muses of Cupica and Nicaragua, in which the 

 height of the ridge of partition is very inconsi- 

 derable, is nearly the same as the breadth of 

 the land crossed by the artificial part of the Cale- 

 donian canal. The isthmus of Nicaragua, by the 

 position of its inland lake, and the communica- 

 tion of that lake with the Atlantic, by the Rio 

 San Juan, presents several features of resem- 

 blance with that neck of land in the Scotch 

 Highlands where the river Ness forms a natural 

 communication between the mountain lakes 

 and the gulf of Murray. At Nicaragua, as in 

 the Scotch Highlands, there would be but one 



