DRY FARMING CONGRESS. 



199 



drouth of 1903 and 1904, by only half an inch. In other words, the pre- 

 cipitation during the past ten years, which has been the period of in- 

 creased rainfall, and on which the claim is based, is greater than the 

 precipitation for the preceding ten years, which included that of the 

 drouth, by only one-half an inch. 



Now, this lower curve represents the seasonal precipitation; that is, 

 the precipitation for the six months, April to September. Of course, we 

 must follow in a general way the precipitation for the whole year. The 

 difference between the two curves would represent the precipitation falling 

 during the remaining six months of the year, which averages, for the 

 area., about five inches. The summer curve you will see follows that of 

 the winter curve with this rather important exception, that during the 

 summer months — during the time, in other words, when the precipitation 

 is of utmost availability, we did actually get considerably more precipita- 

 tion during the summer months than in the case of the preceding ten 

 years. This shows the importance of differentiating between the seasonal 

 precipitation and the total precipitation, which is of less value in consid- 

 erations of this kind. 



The next slide will show the conditions at Dodge City, Kansas, in 

 the central part of Kansas, and is shown here for the purpose of illustrat- 

 ing the great fluctuations which occur at any single station. You see 

 how much this goes up and down as compared with the average curve 

 for the whole territory. Of course this shows at Dodge City as in all 

 of the other cases, the great drouth of 1894 and 1895. It must show most 

 of the great differences which are shown in the other curve. It also 

 shows an extremely high precipitation in 1906, whereas the high precipi- 

 tation for the area was in 1905. What is far more important for the 

 Great Plains than the claim of an increased rainfall, which even if it ex- 

 isted could only be of a temporary character, is the fact that the settle- 

 ment of the Great Plains from 1895 to 1905 has been made on a practically 

 normal rainfall. 



If I may have the first slide again, for a moment, please. 



Far better this than an agricultural established during a series of wet 

 years, which with even a normal rainfall would be fraught with adversity. 



There is one point in that first slide I would like to call your atten- 

 tion to in this connection, namely, how uniform this line is as compared 

 with that of the preceding year when we had these tremendous fluctua- 

 tions, far more water than was absolutely necessary for carrying on the 

 agriculture in that locality. Here are the averages of remarkably uniform 

 conditions — remarkably favorable conditions for the agriculture of that 

 region. 



Evaporation is a factor of equal importance with precipitation in de- 

 termining the agricultural productiveness of a region. By the term 

 "evaporation" is meant the number of inches of water which vaporizes or 

 evaporates from a clean water surface in a freely exposed open tank 

 during a given period. Thus the annual evaporation is the total number 

 of inches of water which evaporates during the year, just as the precipita- 



