450 MINNESOTA STATE HORTICULTURAL SOCIETY. 
manency, even if the rainfall is, according to familiar belief, grad- 
ually decreasing. 
As the question of rainfall stability has a very important bearing 
upon the matter in hand, it is perhaps well to throw what light we 
can upon this point before proceeding farther. 
The best authorities now agree that the presence of extensive 
forests tends to slightly increase the precipitation, and, on the other 
hand, deforestation to correspondingly lessen it. Our lands are 
being rapidly denuded of timber, and it seems as if this had been 
carried on sufficiently to measurably affect the rainfall, provided 
any loss from this cause was ever to become appreciable. 
The longest rainfall record within the state is that taken at Fort 
Snelling, beginning in 1836 and continuing with but few interrup- 
tions until 1892. By means ofa St. Paul record kept only a few miles 
distant, the missing intervals have been very closely approximated 
and the observations made continuous for a period of fifty-seven 
years. 
I have carefully examined this and found it impossible to detect 
the slightest permanent diminution in annualamounts. A further 
proofof past rainfall constancy, during thousands of years, is daily 
seen in the character of the soil, which in arid regions is predom- 
inantly sandy and silty, whereas loamy soils, containing consider- 
able clay and known as heavy, have resulted asa rule from an 
abundance of rainfall. It will be found that nothing which man 
can do will ever increase or diminish, except ina very slight degree, 
our annual supply; but the evil effects of drouth will continue to be 
felt with increasing severity owing to deforestation and improper 
cultivation, the latter causing an accelerated waste in moisture by 
evaporation, nearly all of which is carried to distant lands before 
again reaching the earth’s surface. 
According to the latest rainfall charts, our annual supply varies 
between thirty-two inches along the western shore of Lake Super- 
ior and nineteen and one-tenth inches at St. Vincent, in Kittson 
county. Thereis, generally speaking,a uniformly gradual decrease 
in amount from east to west. 
Captain Wheeler, in his report upon the United States geographi- 
cal surveys west of the 100th meridian, says, “Farming without ir- 
rigation may doubtless be safely carried on when the rainfall ex- 
ceeds twenty inches.” If we are to accept twenty inches as the 
line of demarkation below which irrigation only is requisite, I 
need go no farther, as this state contains but a few square miles 
of such territory, and the question would then become one of little 
interestto us. The better way, however, is to treat the matter as is 
done in India, where millions of dollars have been expended by 
the government in constructing a system of irrigation which is 
availablein districts where the annual rainfall is forty inches or 
over, although not expected to be put to practical use oftener than. 
once in three or four years. 
Some crops and small fruits can not be successfully raised unless 
abundantly watered, and a season could hardly pass without the 
cereals being at times benefited by moisture; therefore, until irri- 
