IMPROVEMENTS IN NORTH AMERICAN HYDROGRAPHY. 625 
templated or suggested. One of these is the diversion of the 
Rhine from its present channel below Ragatz, by a cut through 
the narrow ridge near Sargans, and the consequent turning of 
its current into the Lake of Wallenstadt. This would be an 
extremely easy undertaking, for the ridge is but twenty feet 
above the level of the Rhine, and hardly two hundred yards 
wide. There is no present adequate motive for this diversion, 
but it is easy to suppose that it may become advisable within no 
long period. The navigation of the Lake of Constance is 
rapidly increasing in importance, and the shoaling of the east- 
erm end of that lake by the deposits of the Rhine may require 
a remedy which can be found by no other so ready means as the 
discharge of that river into the Lake of Wallenstadt. The na- 
vigation of this latter lake is not important, nor is it ever likely 
to become so, because the rocky and precipitous character of 
its shores renders their cultivation impossible. It is of great 
depth, and its basin is capacious enough to receive and retain 
all the sediment which the Rhine would carry into it for thou- 
sands of years.* 
Improvements in North American Hydrography. 
y 
We are not yet well enough acquainted with the geography 
of Central Africa, or of the interior of South America, to con- 
jecture what hydrographical revolutions might there be 
wrought ; but from the fact that many important rivers in 
both continents drain extensive table-lands, of moderate eleva- 
tion and inclination, there is reason to suppose that important’ 
changes in the course of those rivers might be accomplished. 
Our knowledge of the drainage of North America is much 
* Many geographers suppose that the dividing ridge between the Lake of Wal- 
lenstadt and the bed of the Rhine at Sargans is a fiuviatile deposit, which 
has closed a channel through which the Rhine anciently discharged a part or 
the whole of its waters into the lake. In the flood of 1868, the water of the 
Rhine rose to the level of the railway station at Sargans, and for some days 
there was fear of the giving way of the barrier and the diversion of the cur- 
rent of the river into the lake. 
40 
