no. 9 



FORECAST OF U. S. PRECIPITATION — ABBOT 



II 



curve a is 29.6 percent, and that from curve b is 2.1 percent. The 

 reduction of 93 percent in deviation is due to removing exact har- 

 monics of 39 months. 



Overriding periods. — As another example I quote from footnote 

 1, g, cited above, showing figure 4 of that reference (here figure 7). 



Fig. 5.— Demonstration of 273-month master period in weather. 



From the mean of 16 repetitions of the periodicity of 45-1/2 months 

 in Natural Bridge precipitation, the true 45-1/2-month period is 

 cleared of four overriding harmonics. 4 The reader will note what 

 similarity to true sine curves is attained in both the above examples, 



4 Refer also to the clearing of overriders from the period of 68-1/4 months at 

 St. Louis. Note 1, g, figure 3. 



