126 
gram no crossing of the iron and “unknown” lines had occurred 
though normally to be expected. These unusual solar condi- 
tions prevailing in 1897 to 1900 were accompanied by irregular- 
ities in the rainfall in India, and may perhaps also be reflected 
in the somewhat unusual irregularities in the rainfall records 
and hydrograph in Illinois during this period. The data avail- 
able for the discussion of the periodicity of rainfall are so lim- 
ited that only tentative values can be given to any conclusions 
upon the subject. The striking conformity of the Illinois data 
to the Lockyers’ cycle will perhaps justify this discussion. 
As might be expected, the variation in the rainfall for 
any given point of observation may far exceed that of the 
average for the whole state. Thus we find a record of 74.5 
inches for Muscatine, Iowa, in 1851, while its lowest record is 
23.6—a range of 50.9 inches. These extreme records are gen- 
erally due to local rains of considerable magnitude, which are 
often the cause of the sudden floods in the tributary streams 
of the Illinois. 
The seasonal distribution of the rainfall for Illinois is 
shown in the following table taken from Leverett (96). 
Spring |Summer| Autumn] Winter'| Annual | Cubic miles 
Inches. crterocsten tecrters 10.2 11.2 9.0 7.7 38.1 34.0 
The distribution by months, expressed in percentages of the 
total, is as follows. 
ae TT” | eval van ena vir | vin Ix x [XI XII 
6.2 | 67 7.0 8.2 | 10.4 | [2.2 | 9.9 
The table shows a minimum in December with a gradual 
increase to a maximum in June, from which the decline is 
rapid, with only a slight interruption at the autumnal equinox. 
The tables given above apply to the state as a whole. An 
examination of the individual records shows that the south- 
ern part of the state has a somewhat greater rainfall than the 
