26 CLIMATIC CYCLES AND TREE-GROWTH. 
only. A comparison between the 5 and these oldest 2 taken by them- 
selves give an agreement not absolutely perfect, yet so close that 
errors thus introduced will not materially affect the curves. However, 
the oldest 2 were very slow-growing trees and they required on the 
average an increase of about 30 per cent in order to make their curve 
continuous with the whole 5. Thus the tree-record is made to begin 
at 1385. In the recent years of the record also, between 1891 and 1896, 
a slight correction was made for omitted rings, the complete omission 
of a ring being an exaggeration that introduces error. 
1870 1880 ios 1900 1910 
0.9 A 
ost wy 3 7 
ver / a i 25 sections measured Lendl /\ mG by 
(oo Via Lo ee 
2 k Mos VV] 
se tot 
0.8 7 sections of 1911 \ 
bon ey. NY _|* -\ Al 
e WAAL U 
0.5 Mi r il 30 
Jan. 1 to Jan. 1 es en 
NV AILAR 
30 A i 30 
20 IV Aug. 1 to Aug. 1 bene es VV. 
: f 1, At 4 ta 8 
i MN A OA a: 
& 20 A | \I July 1 to July 14 Nov. 1 to Nov. 1] q | \/ 4 
NY y% me: 
= 1} A 30 8 
i Nha 05 8 
2 A Preceding winter Oct. 1 to Oct. 1 | V % a 
& 15 Nov. 1 to May 1- 20 3 
# to \y \f \ / 20 5 
5 ALA_I. 
15 i Summer I\I \ 0 
a T\ | ib ces Sapa aes Sept. 1 to Sept. 1) v 
10 a | | / 15 
1900 1910 1900 1910 
Year Year 
Fig. 4.—Comparison of two Flagstaff groups. Variations in annual rainfall 
according to month of beginning annual means. 
