CLIMATIC. S3 



to more wooded or watered districts. Were that region reclot A with 

 hardy vegetation, followed by trees, it would make an appreciable differ- 

 ence in moistening the air and increasing the precipitation. 



OUR FOREST ISOTHERM. 



Several years ago, when the forest was less disheveled by axe and fire, 

 it was not uncommon when the temperature indicated five degrees above 

 zero in St. Paul, at the same time the thermometer registered twenty-five 

 degrees below zero, one hundred and twenty miles west on the treeless 

 prairie. It is wonderful what a difference this forest makes in the temp- 

 erature of Minnesota. The isotherm, or line of equal heat, of five degrees 

 above zero in mid-winter, does not run east and west, as it should under 

 equal conditions. "It commences," says Prof. D. R. McGinnis, "about 

 twenty-five miles northeast of Duluth on the shores of Lake Superior, fol- 

 lows down the lake shore to Duluth ; from there, instead of going west, it 

 strikes directly south, and passes a little southeast, possibly twenty miles 

 east of St. Paul, and on to the southern line of the state, and thence 

 through northwestern Iowa." 



OUR GREAT WIND-RREAK. 



Everybody who has taken any observation knows that every small body 

 of timber walling up against our strong winds, shows marked results in its 

 influence upon crops. But slight protection makes a palpable difference. 

 The French gardeners understand this ; they build tight fences some six 

 feet high to protect their plants against a cold wind that comes down 

 from the Alps, along the Mediterranean. Such a fence will protect the 

 gardens situated a hundred miles to the north of Marseilles. 



" According to Becquerel, a simple hedge of six feet in height will give 

 protection to plants a distance of seventy feet, and, according to Hardy, a 

 belt of trees averaging three hundred feet will defend vegetation almost 

 entirely against the action of the wind. Another authority finds for every 

 foot in height, one rod in distance protected." If an ordinary wind-break 

 on the prairie is so efficacious, what must it be on the scale of a great 

 natural forest ? and what should so concern us as its preservation ? 



DEFORESTATION AND CYCLONES. 



The question is often raised whether cyclones, involving hailstorms espec- 

 ially, have any connection with the unforested condition of the country. 

 No positive answer as yet has come from the experimentation of the scien- 

 tists. There are certain cosmic influences at work, lying as yet beyond 

 our analysis. No doubt the configuration of a country, its altitude, its 

 distance from the pulses of the ocean and thence its peculiar atmospheric 

 condition, play a direct part in such phenomena; but is not a forest, or 

 rather the want of a forest, a factor concerned in the solution of the prob- 

 lem? Observations in various parts of the world confirm such a con- 

 clusion. 



