612 ISTHMUS OF DARIEN—SUEZ CANAL. 
and the construction of ports at their termini would in general 
be difficult and expensive, and the harbors and the channel 
which connected them would be extremely liable to fill up by 
deposits washed in from sea and shore. LJesides all this there 
is, in many cases, an alarming uncertainty as to the effects of 
joining together waters which nature has put asunder. A new 
channel may deflect strong currents from safe courses, and thus 
occasion destructive erosion of shores otherwise secure, or pro- 
mote the transportation of sand or slime to block up important 
harbors, or it may furnish a powerful enemy with dangerous 
facilities for hostile operations along the coast. 
The most colossal project of canalization ever suggested, 
whether we consider the physical difficulties of its execution, 
the magnitude and importance of the waters proposed to be 
united, or the distance which would be saved in navigation, is 
that of a channel between the Gulf of Mexico and the Pacific, 
across the Isthmus of Darien. Ido not now speak of a lock- 
canal, by way of the Lake of Nicaragua or any other route— 
for such a work would not differ essentially from other canals, 
and would scarcely possess a geographical character—but of an 
open cut between the two seas. The late survey by Captain 
Selfridge, showing that the lowest point on the dividing ridge is 
763 feet above the sea-level, must be considered as determining 
in the negative the question of the possibility of such a cut, by 
any means now at the control of man; and both the sanguine 
expectations of benefits, and the dreary suggestions of danger, 
from the realization of this great dream, may now be dismissed 
as equally chimerical. 
Suez Canal. 
The cutting of the Isthmus of Suez—the grandest and most 
truly cosmopolite physical improvement ever undertaken by 
man—threatens none of these dangers, and its only immediate 
geographical effect will probably be that interchange between 
