SOLAR VARIATION AND WEATHER—ABBOT Lb 
weather records of the past what are the effects of each of the 14 
solar periodicities on temperature and on rainfall for any desired sta- 
tion. Then, assuming that these influences will continue with the 
same effects in future, and still paying close attention to the seasonal 
changes of phase, one may add together all these effects, and also the 
sunspot-cycle effect, similarly detexiiinied from records of the past, 
and thus prepare a forecast for several years in the future. 
With the aid of my assistant, Miss McCandlish, I have made such 
forecasts of temperature and err iation for several cities in the 
7 73 75 77 79 8) 1683 
1837 39 4&0) 43045. .  ar a9 -) 
7 3] 65 67 
a aries fo 
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FicurE 20.—Levels of Lake Huron (minus 581 ft.). Note the cycles of 28, 46, and 
91 years. (Yearly means.) Great droughts in the Northwest following 1838, 
1886, and 1929 recessions. The grand cycle is 92 years (or better, 91.2). Minor 
droughts following 1859, 1906, and to be expected following 1952. 
United States. They have been very successful in some cases, not so 
much so in others. Figure 21 shows one of the most successful, again 
dealing with the precipitation at Peoria, Ill. We employed the pre- 
cipitation records prior to 1930 to determine the outlines of the pe- 
riodic terms, and then synthesized the expected precipitation through 
1944. As will be seen, 10 years out of the 13 show both in phase and 
amplitude considerable similarity to the event. The later years betray 
an increasing tendency for the prophecy to anticipate in phase. This 
may indicate that some adjustment of length of periods is desirable. 
619830—45——11 
