114 DRY-FARMING 
To determine whether or not the natural winter 
precipitation, upon which -the crops of a large por- 
tion of the dry-farm territory depend, penetrates 
the soil to any great depth a series of tests were 
undertaken. At the close of the harvest in August 
or September the soil was carefully sampled to a 
depth of 8 feet, and in the following spring sim- 
ilar samples were taken on the same soils to the same 
depth. In every case, it was found that the winter 
precipitation had caused moisture changes to the 
full depth reached by the soil auger. Moreover, 
these changes were so great as to lead the investi- 
gators to believe that moisture changes had occurred 
to greater depths. The following table shows some 
of the results obtained :— 
PERCENTAGE OF WATER IN Eacu Foor oF Soin 
Date - 
ver- 
1 | 2 3 | 4 5 oe} 2 | e |e 
Sept, 8, 1902. | 6.37] 7.32| 8.17/ 8.55| 8.26] 9.29| 10.10/ 10.38 | 8.56 
April 24, 1903 | 19.29] 19:08 | 18:83] 16.99 | 13.61| 12.62| 12.24| 12.37 | 15.63 
Increase . . | 12.92| 11.76| 10.66| 8.44] 5.35| 3.33| 214] 1.99 | 7.07 
Aug. 24,1906 . | 8.33| 7.63| 8.42| 9.66] 11.30] 10.75| 9.59] 7.93] 9.20 
May 1, 1907. | 18.17| 16.73 | 17.96 16.88| 16.59| 16.25| 14.98| 13.48 | 16.38 
Increase . . | 9.84| 9.10| 9.54| 7.22] 5.29 5.50 | 5.39 | 5.55 | 7.18 
In districts where the major part of the precipi- 
tation occurs during the summer the same law is 
undoubtedly in operation; but, since evaporation 
is most active in the summer, it is probable that a 
