HOW THE SUN WAEMS THE EARTH — ABBOT 179 



A modest forecasting experiment is undertaken in figure 20. Hav- 

 ing plotted 2 complete 23-year cycles extending from 1875 to 1920, 

 inclusive, and in addition plotted 1 more year — 1921 — I pieced onto 

 the last month of 1921, 12 months of forecast based on a study of 

 the 2 preceding cycles. After having drawn this predicted curve, 

 I then drew the curve of actual observation for those 12 months. 

 Similarly, I proceeded, 1 year at a time, from 1922 to 1982, inclusive, 

 as shown in figure 20. Although the fit between forecasted and ob- 

 served curves is not perfect, the maxima and minima are nearly 

 correctly matched in times, the ranges are usually similar, and the 

 correlation is indeed fairly high. 



And now, ladies and gentlemen, having discussed with 3^ou radia- 

 tion, the earth and moon as depending on solar heating, and pros- 

 pects for solar power, the sun itself in its glowing grandeur, our 

 measurements which prove the sun to be a variable star, the regular 

 periodicities disclosed in the sun's variation, the influence of sun 

 spots on weather, and finallj^ the dependence of weather on the varia- 

 tion of the sun, I conclude the third Arthur lecture. 



72774—35 13 



