1.960 



1.950 



1,950 1.940 



1.940 1.930 



1.930 1.920 



1.920 



FioUBB 2.— Analysis and Ryntbeali of solar varlatUm, 1920-34. The synthetic curve B is drawn below the observed curve A to avoid confusion. Successive derivations of the shorter perlodlcltl, s precede their general mean. The 23-year periodicity presents as yet only 15 years of its 



86923—36 (Face p. 95) 



course and is partly estimated. 



