THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. XIII.] MAY, 1920. [No. 8. 



Continuation of Investigation of a Possible Rainfall 

 Period Equal to One-ninth the Sun-spot Period.* 



BY DINSMORE ALTER. 



IN THE Monthly Weather Revieiu for February, 1921, is 

 published a preliminary report of the investigation of all 

 the state averages of rainfall for the whole United States. 

 Certain conclusions are reached tentatively, subject to further 

 investigation. These are that there is evidence tending to 

 shovv^ the existence of a correlation between rainfall and sun 

 spots and that the rainfall follows a period of one-ninth the 

 sun-spot period, varying its length always to keep in step with 

 the sun-spot cycle. In this paper it is assumed that the reader 

 is familiar with the previous discussion and only very brief 

 reference will be made to any point discussed there. As stated 

 in the conclusion of the other paper, the work has been con- 

 tinued in an attempt to fix more definitely the probability of 

 the phenomenon. 



The first continuation of the work was to answer definitely 

 the question whether it might be that excessive rainfall or 

 severe droughths in a very few of the months under discus- 

 sion had produced the variations noted in the means of the 

 two halves of the time as recorded in the previous paper. To 

 do this, it was necessary to obtain the percentages of rainfall 

 through each of the cycles for which data are available. For 

 the eastern group state averages from two states are avail- 

 able beginning January, 1883, and for all states from the latter 

 nineties. These averages give us twenty-four consecutive 



* Received for publication August 5, 1921 



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