119 



luinimum anmial precipitation for these stations is as follows : Bloom- 

 ington, 33.14 (in 1901); Taoli, 20.12 (in 1901); Jeffersonville, 30.18 (in 

 1904); Marengo, 32.37 (in 1901); Evansville, 2S.G.5 (in 1S87) ; Rome, 

 3r..86 (in 1901) ; Mt. Vernon, 34.10 (in 1902).^ At Indianapolis, which 

 has a rainfall record going back without interruption to 1871, a period 

 of forty years, the minimum, recorded precipitation for any one year 

 is 30.33 inches, in 1901. 



An analysis of these data by seasons is interesting, and for our 

 purposes more valuable than ai<y other. Water-supply engineers are 

 agreed on dividing the year into tliree periods, as follows: (a) The 

 storage period, which in this latitude is ordinarily made to include the 

 months from December to May, inclusive; (b) the growing period, from 

 June to August, inclusive; and (c) the replenishing period, from September 

 to November, inclu.sive. It is a welMcnown fact that in many years, 

 and especially in dry years, the run-oft" is practically confined to the 

 months from December to May, inclusive. It is imix)rtant to ascertain, 

 therefore, what is the niinimam expectation of rain in these months. 

 From the stations reporting there have been the following low precipita- 

 tions during the storage period: Bloomington, 14.35 (Dec, 1895, to May, 

 1896) 16.58 (Dec. 1900, to May, 1901) ; PaoII, 13.03 (Dec. 1900 to 

 May, 1901); Jeffersonville, 15.80 (Dec, 1888, to May, 1889), 13.02 (Dec, 

 1900, to May, 1901); Marengo, 14.58 (Dec, 1900, to May, 1901); Evans- 

 ville, 11.83 (Dec, 1900, to May, 1901) ; Mt. Vernon, 12.70 (Dec, 1900, to 

 May, 1901). The year 1901 will be remembered as one of the most dis- 

 astrously dry seasons on record. It is clear, from the above data, that 

 as low as 12 inches of rain may be expected within the area, during the 

 slorage period. A deficiency in this period is rarely made up by an 

 excess of rainfall in the other periods of the year. In fact, a very 

 considerable excess would be necessary to overbalance the effects of a 

 deficiency in the winter and spring months. In other words, a i*elatively 

 wet summer, following a dry winter and spring does not necessarily 

 mean an ample supply of water for municipal use. During the summer 

 months not only is all of the rainfall ordinarily consumed in the growth 

 of plants and in other sources of evaporation, but in addition the gi'ound- 

 water is more or less extensively drawn upon, leaving a deficiency of 

 ground- water at the end of the growing season, that must be made good 



'1901, for which one Qiouth's i-eport is lacking, was undoubtedly drier by 

 several inches than 1902. 



