

ILLUSTRATIONS 



PLATES 



Page 



1. Smithsonian solar radiation station, Montezuma, Chile 3 



2. The periodometer 3 



3. Bolographs of the solar energy spectrum 6 



TEXT FIGURES 



1. Diagram of silver-disk pyrheliometer 4 



2. Diagram of water-flow pyrheliometer 5 



3. Diagram of spectrobolometer 7 



4. Solar-constant values, three stations, 1925-1930 8 



5. March of solar variation, 1920-1934 9 



6. The I i-month periodicity in solar variation 11 



7. Analysis and synthesis of solar variation, 1920-1934 12 



8. Predicted and observed solar variation 15 



9. Sun-spot numbers and phase changes. The 11 -month periodicity in 



temperature departures at Bismarck, N. Dak 16 



10. Wolf sun-spot numbers, 1810-1933 20 



1 1. Eleven-month periodicity in Berlin temperatures 23 



12. Eight-month periodicity in Berlin temperatures 27 



13. Sun-spot numbers and phase changes. Eleven-month temperature 



periodicity at Berlin for low, medium, and high sun-spot numbers... 30 



14. Dependence of phase in periodicities of Berlin temperatures on epoch 



measured from 1819 32 



15. The 23-year influence on periodicities of 9I and 12 months 34 



16. The II- and 21 -month periodicities in Berlin temperatures 36 



17. Details of the 11- and 21-month periodicities in Berlin temperatures. ... 39 



18. The 68-month periodicity in Berlin temperatures 45 



19. Periodic curves at various stations 47 



20. Periodicities of 92 and 138 months, Berlin temperatures 50 



21. Residuals after removing periodicities, Berlin temperatures 51 



22. Trials of periodicities not related to 23 years 52 



23. Cape Town periodicities in temperature departures S3 



24. Cycles in the precipitation of southern New England 59 



25. Levels of Lake Ontario, 23-year cycles 60-61 



26. a and b. Levels of Great Lakes, 23-year cycles 62, 63 



27. Catch of mackerel and cod in the North Atlantic, 23-year cycles from 



1812 to 1931 65 



28. Low-level stages of the River Nile, showing 23-year periodicity, 735 to 



1424, and 1839 to 1885 68 



29. Cycles of 23 years in tree-ring widths. Average results of 115-year 



intervals 70 



30. Cycles of 23 years in tree-ring widths. Individual cycles of 23 years 72 



iv 



