CLIMATIC. 85 



to move in zones, and are attended with a ''peculiar periodicity." The 

 remedy is simple and within our power to apply without recourse to the 

 legislature for special appropriations to relieve the sufferers who have lost 

 their crops by hailstorms. Build up long and wide belts of trees in the 

 storm zone so as to divide them, or at least weaken their force of destruc- 

 tion. 



GENERA!, TREND OF OUR WINDS. 



Warning against desert conditions arising from forest destruction, Prof. 

 W. M. Hayes, of the Experiment Station, St. Anthony Park, demonstrates 

 by "the lay of the land" that, while our principal winds in the continental 

 trough from the northwest and southwest collide into confusion, their gen- 

 eral trend is eastward as resultant of their combined force, and find their 

 "escape across the lakes and down the St. Lawrence river to the ocean. 

 That there is something of such a resultant wind is shown by the fact 

 brought out by meteorologists, that the most cyclonic storms of this valley 

 pass from the west toward the northeast, having, as some one has said, 

 their focal center in the vicinity of Iceland. The flowing of this air 

 toward the eastward carries most of the moisture to the region east of the 

 Mississippi, there giving up enough moisture to have fostered the primitive 

 forests with which all that region was covered. The moist air flowing 

 away from the elevated plain of the West, left that region supplied with 

 air largely from the northwest and southwest. This air, not containing a 

 great amount of the moisture, is warmed up and made to absorb rather than 

 precipitate moisture; hence the low humidity of the air, the small rain- 

 fall and the consequent absence of trees on the plains and prairies." 



THE AERIAL BATTLE GROUND. 



Minnesota being the average highest land in the continental trough, the 

 winds from the gulf meeting those of the cooler northwest are here 

 naturally cooled down to precipitation when the air is sufficiently saturated 

 with moisture.- These meteorological forces, together with those of our 

 prairies, highlands, lakes and forests especially, make Minnesota the mid- 

 continental battle ground of the winds, the lower strata of which are 

 whirled in various directions, just as local conditions necessitate, while the 

 strata above the trees and hills are left freer to sweep eastward. Owing 

 to environment, evolving temperamental changes, the collision of the lower 

 strata of winds educe fogs, clouds and showers. 



FORESTING THE GREAT PLAINS. 



Westward toward the Rockies, known as the Great Plains, there is, 

 comparatively, a scarcity of fogs, clouds and dews, and therefore, dimin- 

 utive precipitation. This is mainly due to the intense equilibrium of 

 sun-heat in that region. Hence the southwest winds of summer, blowing 

 over those hot plains, falling alike on the Minnesota prairies, are ruinous, 

 sometimes blighting all before them. And such winds will continue to 

 bring drouth and agricultural disaster so long as the plains are treeless. 



