FOREST CFLTIVATIOX ON THE PLAIXP. 325 



Stations. April. 



Denver 



Coriuue 



Cheyenne 



Viri;iui.i Cirv 



Fort Snllv .' (Xo obs'n.) 



Fort Benton | 0.67 



Omaha 3.64 



2.09 

 1.43 I 

 1.61 



0.35 



The records at all points of observation are uufoi tanately too brief to 

 afford any i)roper means of determining whether the quantity of rain is 

 greater now than it was ten years since; though great force attaches to 

 the almost nniversal belief in such increase on the part of the more in- 

 telligent residents and observers in the interior. The range of non- 

 periodic variation is very great in all parts of the temperate latitudes, 

 and it is possible that our earliest practical experience on the plains was 

 in a period characterized by a succession of dry seasons. In Utah it is 

 quite clear that practically the warmer seasons have become far more 

 profuse in rain-fall than they were fifteen years ago ; and at the eastern 

 foot of the mountains, the settled localities, as Denver, and the dis- 

 tricts both south and north of the original center of settlements, afford 

 marked evidence of improvement. But there are no statistics of meas- 

 urement which afford any positive evidence ; the periods observed at 

 the military posts being quite irregular, and not sufficiently extended to 

 establish anj' law of increase. 



On no point of practical results are both writers and observers more 

 thoroughly agreed, than in affirmiug the value of forests, as agents of 

 at least local amelioration of climate. An essential condition of the 

 gi'owth or imiirovement of a soil by chemical decomposition of its ele- 

 ments and by the deposit in or on it of vegetable mold, is the constant 

 permeation of its strata by the water of rains and snows. These 

 waters bear more or less ammonia always with them, which is the chief 

 agent of rock decomposition, and in practical experience the forest-soils 

 of tha Central States are found deeply decomposed and fertilized. 

 They are also free in absorbing water, holding it long, and yielding it 

 slowly by subsequent evaporation and by drainage through the surface 

 strata in i^ermanent springs. The first result of too gTeat and general 

 clearings of the forest is to dry up the springs, and next to harden the 

 snrface-soiJ, forming a stiff' mass which sheds the water of ordinary 

 rains, and can only be permeated by water and by the roots of plants 

 when thoroughly broken up and fertilized by artificial means. xVfter 

 long iieriods of exposure the surface becomes so hard and refractory as 

 to bear little or no resemblance to the soft, moist, deep soil of the orig- 

 inal woodland. The denudation of the hills and upland plains of ar.y 

 one of the Central States will show a marked decline in iiroductive ca- 

 pacity, from that belonging to the original or first occupancy. At that 

 time the wealth of the soil had not been wasted, nor had the general 

 exposure of the surface deprived the crops of the shelter of adjacent 

 woods, preventing the dry and caustic winds from exhausting the vi- 

 tality of every plant exposed to them. 



The ordinary condition of the atmosphere, as it sweeps in general pro- 

 gress eastward, is that of an absorbent of moisture. When rain is not 

 actually falling the air is taking up moisture, and if nothing is offered 

 to it by ordinary evaporation from the surface tlie condition soon be- 



