unced and everywhere visible. Less than two degrees of
longitude _east_ of these mountain ranges there is but about (taking the
whole line from the thirty-fifth parallel to the northern boundary) an
average fall of seven and a half cubic inches of rain, a difference of
over fifty-five cubic inches within the year, in districts separated by
less than one hundred miles in a straight line from each other. The
consequence is, that, while in one there is a luxuriant growth in all
kinds of vegetation, in the other barren plains (destitute of all except
the lowest forms of vegetable life) exist, with a gradual but slow
return, as the eastern course of the winds are followed, to that normal
condition which prevails in districts where an abundant supply of
moisture is furnished. This is not fully found till the western limit of
the third climatic division is reached, where again we see on all hands
a general distribution of rivers and forests over the whole of this
area, with copious rains at all seasons, and humid and cool conditions
of the atmosphere, following each other in rapid alternations; producing
what we have seen fit to call the Variable climatic district, embracing
the whole eastern half of the continent.

The extreme high temperature of the interior division equals that of
points lying a dozen degrees south in other longitudes, and the
desiccated winds from the west, as they blow over this parched and
heated surface, have their aridity rather than their humidity increased,
as would be the case in other circumstances; and not till they reach
within perhaps five hundred miles of the eastern boundary of this
continental division do they increase in humidity, as indicated by the
rain-fall, which rises in quantity from the low minimum of seven and a
half cubic inches per annum in the "great basin," and fifteen on the
"great plains," to about twenty in Dakota territory and twenty-five in
Minnesota, the eastern limit of this continental climate.

The effect of these dry winds on the humidity of the atmosphere in
Minnesota is unquestioned and demonstrable by the records kept of the
various governmental posts over the whole country. In contrast, the
amount of rain falling annually in this State is shown by these
statistics to be much below that of any lying east of the Mississippi,
in the variable-climatic district; and, indeed, below that of every
other in the entire Union, excepting Nebraska, which averages about the
same