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 amount of rain-fall, though without the same amount of dryness and elasticity, which are such notable features in the atmosphere of the former State.

The mean annual amount of rain falling in New England is about forty-three inches, nearly double that of Minnesota, exhibiting the vast difference in the humidity of the two localities, and this, in connection with the cold easterly winds before referred to as prevailing there at intervals, together with the severe changes (and which, it should not be forgotten, add to the quantity of moisture), may be ascribed the primal cause of all pulmonic diseases.