CONTENTS. 
ED 
PAGE. 
J, INTRODUCTION. ...--0- e+ ee eres 9 
Trees suitable for climatic study..... 11 
Introduction to special studies on the 
yellow pine......+-++e+eeesereee 12 
Location......6.e+-seeeeeeeeee 12 
Climate and seasonal conditions. 13 
II. PRELIMINARY STUDIES ON THE YELLOW 
MUO piiecads ss 5 27.0.3 \Asitep: 
Yearly identity and the dating ofrings 15 
Cross-identification......++++s+++++ 16 
Cross-identification and climate. 17 
Month of beginning annual means... 17 
The time of year of ring formation... 18 
Significance of subdivisions in 
FINGS...-. 0. ee ceseeesesreres 20 
Number of trees necessary for reliable 
resultS.....-escceeer creer rtsett 21 
Direction of maximum growth. . 22 
Rate of growth and age....---- 22 
Growth and soil........+++++5+ 22 
III. CoLLEcrion OF SECTIONS.....+-++--> 23 
The first Flagstaff group of 25 sections 23 
Subgroups........-++++sse05- 24 
First suggestion of cross-identifi- 
CRON ii ccc ee eee ccc en ts 
The Flagstaff 500-year record.... 24 
The second Flagstaff group of 7 sec- 
RE rete center Se aryN et? 27 
The Prescott group.......+++++++++ 27 
South of England group.......----- 29 
Outer coast of Norway group.....-- 30 
Inner coast of Norway group.....-- 32 
Christiania group. ...-.-++seseeeee 35 
Central Sweden group.....-.++++++: 35 
South Sweden group.......+++s+5+5 36 
Eberswalde (Prussia) group......--- 37 
Pilsen (Austria) group.....--++-++- 39 
Southern Bavaria group.......---+> 39 
Old European trees.......+++-+++++ 40 
Windsor (Vermont) group.....---++ 41 
Oregon group....-.-.seeeeeeere eee 42 
The Sequoia group......++. ++ +++ree* 44 
The Sequoia journey of 1918......-.. 49 
IV. DETAILS OF CURVE PRODUCTION....- 54 
Preparation of radial samples......- 54 
Form of sample......-..+++++5 54 
Method of cutting........++-+ 54 
Preparation for measurement. . . 55 
Identification of rings........-+++++ 55 
Fire-scars........-020eeee08ee8 56 
Cross-identification between dis- 
tant points.....-.--.+ee reer 57 
The difficult ring 1580........ 58 
Measuring.........+0--+seeeeeeere 58 
Tabulating.........50.sceeveescers 59 
Averaging........:0ee cere eeeeees 60 
Smoothing..........ccceeeceennees 61 
Standardizing..........++-eeeeeee8 63 
Plotting... ....-.ccesecceseeveess 64 
Problems in plotting.........-- 64 
YV. CorrELATION WITH RAINFALL......-- 65 
Result of study of curves....... 65 
Early tests of Yainfall correla- 
MARE exe arid ovens zee thin time: 65 
The Prescott correlation.........+++ 66 
AGGUTACY... oes cece tere nevere’ 66 
PAGE. 
V. CorRELATION WITH RAINFALL—contd. 
The Prescott correlation—continued. 
Mathematical relation of rainfall 
and growth.......++++++e+5 67 
Character of the conservation 
COPID a hce hues ao eer rem aias 
Summary.......-++seeeee reese 70 
Sequoia correlation with rainfall. 70 
Future work......- Beira OM Bat 72 
Meteorological districts...-..-.+-++- 72 
Meteorological districts and 
growth of trees.....-.++++"+* 72 
Arizona and California.....-.-- 73 
Meteorological districts and solar 
correlation......-++-+ee8e++" 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.......+-++ees2000* 81 
Suggested causes of sunspots... - 82 
Length of the sunspot period... 84 
Tree-growth and solar activity.. 84 
VII. Meruops 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 
Theory......ssececeeerecsetee 
The automatic optical periodograph. 92 
The curve......eeeeeeeeeeeeee 92 
Track and moving mechanism. . 92 
Differential pattern mechanism . 93 
The periodogram mechanism.... 94 
Periodograms....--++++++e505+ 96 
Resolving power of the periodo- 
graph......eeeeeeeeeeerees? 96 
VIII. Crcnms.......cccsvecrecsceseeee 98 
Significance of cycles....-.-++++ 98 
Predominant cycles......+-++++ 98 
Locality and solar cycles....-.- 99 
Illustrations of cycles.....----- 101 
The ll-year cycle.....-+.++++++ 101 
The ll-year cycle in sequoia.... 102 
Correlation curves.....-+++++++ 103 
Double and triple cycles.....---- 103 
A Q-year cycle......ssse seers 106 
Periodograph analyses......--++++++ 107 
Differential patterns......-.+--- 107 
The ll-year cycle......--++++++ 107 
Changes in the 11-year tree-cycle 
of ATizona......6--e essere 108 
Sequoia pattern......-.++++++> 109 
Other solar cycles......-.++++++ 109 
The 100-year cycle.......---+-+ 110 
Illustration by the periodograph. 110 
Summary.....csseeeeereeeeerreeee 111 
Addendum......se-seeeeeertrrret? 112 
APPENDIX.....-.-sccceeeeer es seseeenes 113 
Tables of mean tree-growth by groups 113 
Bibliography.......6--e++eeeeeeeee 124 
