FOREST PLANTING. 123 



yet in active operation, aided by potent agencies not then in exist- 

 ence. Then the locomotive was unknown west of the Mississippi ; 

 now there are in Iowa, Missouri, Nebraska and Kansas thousands of 

 miles of railroad. Then the entire population of the United States 

 was only about twenty-one millions ; now it is over forty millions. It 

 is safe to say that the forces operating to throw population westward, 

 taking into consideration facilities of transportation, are three times 

 as powerful as they were twenty-five years ago. The result will be a 

 gradual spread of people over the great plains, arranging their pur- 

 suits and modifying their habits to suit the capabilities of the country 

 and the necessities of their respective localities. 



EFFECT ON CLIMATE. 



It is a bold assumption to say that the spread of settlements over 

 the plains is to materially affect the climate. Yet it is not unreason- 

 able to expect a degree of amelioration. Every house, every fence, 

 every tree which civilized communities may in the future establish in 

 those vast, open areas, will aid, in some measure, to check the sweep 

 of the winds. Every acre broken by the plow will retain a greater 

 amount of moisture after rains, and for a longer time, than the 

 unbroken prairie. The genial rains of spring and summer will evap- 

 orate with less rapidity, and there will be a greater degree of humid- 

 ity in the atmosphere, heavier dews, and possibly more frequent 

 showers. Even if the annual average of rainfall shall not be increased, 

 the chances are that it will be more evenly distributed. If we may 

 judge by the experience of other parts of the world, where the 

 destruction of forests has operated to dry up fountains, we may reason- 

 ably expect that the breaking up of the surface by the plow, the 

 covering of the earth with taller herbage, and the growth of trees, 

 will all tend to the development of springs where now unknown, and 

 to render streams perennial which are now intermittent. Thus the 

 gradual spread of inhabitants over the plains will tend to enlarge 

 their capabilities and to render them more habitable. 



Under date of June loth, 1872, Mr. Elliott writes me 

 as follows : 



