104 CLIMATIC CYCLES AND TREE-GROWTH. 
the curve a little but not enough to change the pronounced fluctuations 
amply shown in recent analysis. This 200-year record showed a very 
clear combination of the double and triple sun-spot periods. This 
was illustrated at the time in a drawing which is largely reproduced 
in figure 35. Curve No. 1 is a triple solar cycle 32.8 years in length; 
hymen. 
IN Arik. Pine | F 
N ¢ NX 
agomm. Lo my Z N ta ee 
(andl Pied as, Gos? ya Al os 
F) elelind Mh NA (500 yrs) 1 3 
& id ig 25 a: ae eae) ¢ 
285mm A—| Sequoia ~L A 
i IN ‘ss i 
§ 7 / ng 7 oN aise 
Bel TL Ne teak re Wiel diye I 
2 Ariz. Pine 
& 400mm on ~<S st G4 yrs) | comm 
0.95mm = Bl KO Cae . be “ 
pert oe Segivia Pasd e na alee 
am Al is 
Y \ Letpdintall \ LN oink 
~ 4+’ IN yee ee é 
S 40s { ~~ N/ Ll gin. 
N t Last 60 yrs, So Capt 
402° 42) 828 7 
p ae TepipErarure._ 
i 7 oo eg esa 7 
0.49 PSY 
J a 
ma I NX Supspoh No? (mverted) =a he ; 
NI (4¢s7|60 yrs) ‘ 
N 1A 
NG tae “i i 
s 1 
V2 8 £8 6.8 eee we 
Years 
Fig. 34.—Correlation curves in the 1l-year cycle. 
No. 2 is a double cycle 21.2 years long, and the third curve is a simple 
combination of the two. The fourth curve is the tree-growth, showing 
fluctuations which admirably combine these two periods. All sub- 
sequent analysis of these trees has entirely supported this result, as 
shown in the periodograph work below. When the length of curve was 
extended from 200 years to 500 years, the double solar period was 
found to prevail through almost the entire length, but the triple period 
does not appear to have affected the tree-growth in the earlier 300 years. 
Two other plain examples of the double solar type are illustrated in 
figures 36 and 37. The former gives the double cycle shown in a scat- 
