ILLUSTRATIONS. 



TEXT-FIGURES. 



PAGE. 



1. Effect of monthly distribution of pre- 

 cipitation on thickness of rings of 

 growth; Prescott, Arizona 19 



2. Monthly and yearly precipitation at 

 Prescott, and size and character of 

 rings 21 



3. Annual growth of trees at Flagstaff 



from 1385 to 1906, A. D 25 



4. Comparison of two Flagstaff groups. 

 Variations in annual rainfall according 



to month of beginning annual means . 26 



5. Growth of individual trees compared 

 with precipitation at Flagstaff 27 



6. Annual growth of trees near Prescott, 

 Arizona 28 



7. Annual rainfall and growth of trees 



(Group V) at Prescott. Dotted line 



=rainfall. Solid line=growth 29 



S. The nine European groups 31 



9. Sunspots and growth of trees at Ebers- 

 walde, Germany 38 



10. Growth of old European trees. A. Six 



Norwegian trees, mostly from inner 

 fjords. B. Eight trees from Dalarne, 

 Sweden 40 



11. Oregon group. Curve No. 1, actual 

 tree growth; No. 2, trees growth de- 

 partures, smoothed; No. 3, sunspot 

 numbers displaced 2 years to left .... 43 



12. Cross-identification in first five sequoias 



and gross rings in No. 1 48 



13. Correlation between tree growth and 

 rainfall in smoothed curves; Flagstaff. 65 



14. Early test of correlation between tree 

 growth and rainfall by years ; Flagstaff 66 



15. Relation of tree growth and rainfall at 



Prescott. Tree growth and rainfall 

 unconnected 68 



16. Five-year smoothed curves of growth 

 and rainfall 68 



17. Accumulated rain and smoothed tree 



growth 68 



18. Actual tree growth and growth calcu- 

 lated from rain 68 



19. Actual rain and rain calculated from 

 tree growth 68 



20. Huntington's early curves of sequoia 

 growth and rainfall compared with 

 growth calculated by a conservation 

 formula 71 



21. Comparison of Fresno rainfall (after 



Huntington) and sequoias D-l to 5. . 71 



22. Sunspot numbers and annual rings in 

 spruce tree from south Sweden 75 



PAGE. 



23. Six European groups, standardized 

 and smoothed 75 



24. Three European groups, standardized 

 and smoothed 77 



25. Comparison between 57 north Europe 

 trees (smoothed) and sunspot num- 

 bers. The trees are from England, 

 Norway, Sweden, and north Germany 77 



26. Dates of large rings in 80 European 

 trees compared with sunspot curves. 

 Ordinates give number of trees in 

 total of 80 showing maxima in re- 

 spective years 78 



27. Tree growth at Windsor, Vermont, 

 showing measures unconnected: same 

 standardized and smoothed, and sun- 

 spot numbers displaced 3 years to left 78 



28. Smoothed quarterly rainfall (upper 

 curve), sunspot numbers (center), 

 and tree growth (lower) at Windsor, 

 Vermont, 1835 to 1912 79 



29. Correlation curves of solar cycle, rain- 

 fall, and tree growth at Windsor, Ver- 

 mont, 1835 to 1912 80 



30. Schuster's periodogram of the sunspot 

 numbers 86 



31. Diagram of theory of differential pat- 

 tern in periodograph analysis 91 



32. Smoothed curve of Arizona pines show- 

 ing the half-sunspot period for 120 

 years 102 



33. Changes in the 11-year period in 500 

 years. Solid line, Arizona pine; 

 dotted line, sequoia 103 



34. Correlation curves in the 11-year cycle 104 



35. Early curve of Arizona nines from 1700 

 to 1900 A. D. (No. 4) compared with 

 double and triple sunspot cycles com- 

 bined (No. 3) 105 



36. Double sunspot period in tree growth 

 at inner fjords of Norway; lower curve 



a 22.8-year cycle 105 



37. Double sunspot rhythm in sequoia, 

 D-12 about 300 A. D 105 



38. Triple sunspot cvcle in a single tree 

 from northern Norway. Lower curve, 



a 34-year cycle 106 



39. D-22 at 750 to 660 B. C., showing a 

 2-year period 106 



40. Two differential patterns of Hunting- 

 ton s preliminary 2000 year sequoia 

 record. The most prominent cycle is 

 about 105 years in length, shown in 

 the upper diagram 109 



