June 14, 1858.] 
AND THE ADJACENT COUNTRIES. 
341 
the crest of the Great Alleghany range, is 69 miles long. This canal 
is the eastern outlet for the great interior basin of the country, as 
is the Mississippi River of the southern. On going still farther north- 
east, another remarkable depression occurs in the general surface of 
the country, being that occupied by Lake Champlain. This lake is 
elevated only 87 feet above the level of the sea. Easterly of this 
depression, which extends all the way from the St. Lawrence River 
to the Hudson, the dividing line between the St. Lawrence and the 
rivers flowing into the Atlantic Ocean is a well defined and com- 
paratively lofty mountain range. 
The last grand division shown on the map is the Atlantic slope of 
the Alleghany mountain ranges. This is comparatively insignificant 
in extent, though at present the principal seat of the population 
of the United States, and of its leading commercial and agricultural 
communities. It extends from the Gulf of St. Lawrence to the 
Gulf of Mexico, embracing the two lower British North American 
Provinces. It has an average breadth of about 350 miles. This 
division is composed of belts of country very dissimilar in their 
aspects. With the exception of the New England States and the 
Provinces named, that portion of it lying immediately upon the 
sea-coast is low and marshy. The width of this belt varies all the 
way from 10 to 50 miles. This is succeeded by a more elevated, 
though comparatively depressed and level belt, composed of sandy 
plains, covered with pine forests. The slopes of the plateau from 
which rise the Alleghany Mountains are next reached, and with 
them, the most fertile portions of the Eastern States. The general 
elevation of this plateau is about 2000 feet above the sea. Upon 
this, the mountains rise to an elevation, in some cases, of over 
6000 feet above the sea. The breadth of the Alleghany range of 
mountains will average from 200 to 300 miles. For the greater 
part of their height they are composed of several parallel ranges, 
having the general direction of the Atlantic coast. 
As I did not expect to be called upon to make any remarks, such 
as I have made have necessarily been somewhat discursive, and 
totally inadequate to so broad a subject as the topography of the 
United States. The map now exhibited will supply the want of 
greater detail on my part. I have only attempted a brief outline. 
The map is based on the coast survey of the United States, con- 
ducted by Professor A. D. Bache, whose eminent scientific attain- 
ments, I am happy to know, are properly appreciated by your 
learned Society. The interior is compiled from the surveys of public 
lands of the United States, and the surveys of several proposed 
routes for railways across the continent, and surveys conducted 
