CONTENTS. 



PAGE. 



I. INTRODUCTION 9 



Trees suitable for climatic study 11 



Introduction to special studies on the 



yellow pine 12 



Location 12 



Climate and seasonal conditions. 13 



II. PRELIMINARY STUDIES ON THE YELLOW 



PINE 15 



Yearly identity and the dating of rings 15 



Cross-identification 16 



Cross-identification and climate. 17 



Month of beginning annual means. . . 17 



The time of year of ring formation. . . 18 

 Significance of subdivisions in 



rings 20 



Number of trees necessary for reliable 



results 21 



Direction of maximum growth . . 22 



Rate of growth and age 22 



Growth and soil 22 



III. COLLECTION OF SECTIONS 23 



The first Flagstaff group of 25 sections 23 



Subgroups 24 



First suggestion of cross-identifi- 

 cation 24 



The Flagstaff 500-year record. ... 24 

 The second Flagstaff group of 7 sec- 

 tions 27 



The Prescott group 27 



South of England group 29 



Outer coast of Norway group 30 



Inner coast of Norway group 32 



Christiania group 35 



Central Sweden group 35 



South Sweden group 36 



Eberswalde (Prussia) group 37 



Pilsen (Austria) group 39 



Southern Bavaria group 39 



Old European trees 40 



Windsor (Vermont) group 41 



Oregon group 42 



The Sequoia group 44 



The Sequoia journey of 1918 49 



IV. DETAILS OF CURVE PRODUCTION 54 



Preparation of radial samples 54 



Form of sample 54 



Method of cutting 54 



Preparation for measurement ... 55 



Identification of rings 55 



Fire-scars 56 



Cross-identification between dis- 

 tant points 57 



The difficult ring 1580 58 



Measuring 58 



Tabulating 59 



Averaging 60 



Smoothing 61 



Standardizing 63 



Plotting 64 



Problems in plotting 64 



V. CORRELATION WITH RAINFALL 65 



Result of study of curves 65 



Early tests of rainfall correla- 

 tion 65 



The Prescott correlation 66 



Accuracy 66 



PAGE. 



V. CORRELATION WITH RAINFALL contd. 



The Prescott correlation continued. 

 Mathematical relation of rainfall 



and growth 67 



Character of the conservation 



term 67 



Summary 70 



Sequoia correlation with rainfall. 70 



Future work 72 



Meteorological districts 72 



Meteorological districts and 



growth of trees 72 



Arizona and California 73 



Meteorological districts and solar 



correlation 73 



VI. CORRELATION WITH SUNSPOTS 74 



Dry-climate tests 74 



Wet-climate reaction 74 



The European groups 76 



Windsor (Vermont) correlation. . 79 

 The sunspots and their possible causes 81 



Appearance 81 



Suggested causes of sunspots. ... 82 

 Length of the sunspot period ... 84 

 Tree-growth and solar activity . . 84 



VII. METHODS OF PERIODIC ANALYSIS . ... 85 



Need for such analysis 85 



Proportional dividers 85 



The optical periodograph 86 



Schuster's periodogram 86 



The optical periodogram ....... 86 



Application to length of sunspot 



period 88 



Production of differential pattern 89 

 Theory 90 



The automatic optical periodograph. 92 



The curve 92 



Track and moving mechanism . . 92 

 Differential pattern mechanism . 93 

 The periodogram mechanism. ... 94 



Periodograms 96 



Resolving power of the periodo- 

 graph 96 



VIII. CYCLES 98 



Significance of cycles 98 



Predominant cycles 98 



Locality and solar cycles 99 



Illustrations of cycles 101 



The 11-year cycle 101 



The 11-year cycle in sequoia.. . . 102 



Correlation curves 103 



Double and triple cycles 103 



A 2-year cycle 106 



Periodograph analyses 107 



Differential patterns 107 



The 11-year cycle 107 



Changes in the 1 1-year tree-cycle 



of Arizona 108 



Sequoia pattern 109 



Other solar cycles 109 



The 100-year cycle 110 



Illustration by the periodograph . 1 10 



Summary Ill 



Addendum 112 



APPENDIX 113 



Tables of mean tree-growth by groups 113 

 Bibliography 124 



