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THE UNIVERSITY SCIENCE BULLETIN. 



Plate VII. — Application of Professor Marvin's periodocrites to various 



periodocrites. 



1. Annual cycle, Washington, D. C, rainfall, fifty-year record. 



2 Annual cycle, Boston rainfall, 103-year record. 



3. Twenty-four cycles ninth harmonic of sun-spot period in Eastern group rainlaU. 



4. Seventeen cycles of same in Western group rainfall. 



