4 
the scene of astronomical or barometrical observations, furnish the mate- 
rials out of which this map has been constructed. Nothing supposititious 
has been admitted upon it; so that, connecting with Captain Wilkes’s sur- 
vey of the mouth of the Columbia, and with the authentic surveys of the 
State of Missouri, it fills up the vast geographical chasm between these 
two remote points, and presents a connected and accurate view of our con- 
tinent from the Mississippi river to the Pacific ocean. 
To this geographical map, delineating the face of the country over 
which we travelled, there is added another in profile, showing the eleva- 
tions, or the rise and fall of the country from the Mississippi to the Pacific. 
East of the Rocky mountains, two of these profile views are given—one 
from St. Louis to the South Pass, the other from the mouth of the Great 
Platte to the same point. The latter is the shortest; and following, as it 
does, the regular descent of the river, and being seven hundred miles west 
of the Mississippi, it may be that the eastern ¢erminus of this line may 
furnish the point at which the steamboat and the steam car may hereafter 
meet and exchange cargoes in their magic flight across this continent. 
These profile views, following the travelling routes, of course follow. the 
lowest and levellest lines, and pass the mountain at the point of its great- 
est depression ; but to complete the view, and to show the highest points 
as well as the lowest levels, many lofty peaks are sketched at their proper 
elevations, towering many thousands of feet above the travelling line. It 
may here be excusable to suggest that these profile maps here exhibited 
are, perhaps, the most extended work of the kind ever constructed, being 
from St. Louis (according to the route we travelled ) near sixteen hundred 
miles to the South Pass; from the mouth of the Great Platte to the same 
Pass, about one thousand more; and then another sixteen hundred from 
that Pass to the tide water of the Oregon; in all, about four thousand 
iles of profi Mapping, founded upon nearly four hundred barometrical 
positions, with views sketched and facts noted in the field as we went. 
In the departments of geological and botanical science, I have nat ven- 
tured to advance any opinions on my own imperfect knowledge of those 
branches, but have submitted all my specimens to the enlightened judg- 
‘ment of Dr. Torrey, of New Jersey, and Dr. Hall, of New York, who have 
kindly classi and arranged all that I was able to submit to them 
| specimens furnished to him, will be found inan 
¢ formation in the region west of the Rocky 
eh 
a observations of Dr. Torrey will be furnished in full here- 
‘Deing time to complete them now. The remarks of Dr. 
sd op : ts and to his palzontological skill I am indebted for 
