Sra Wsanc ss 
DOUGLASS 
PLATE 12 ; 
DIFFERENTIAL PATTERNS. 
. Sunspot Nos. 1610-1910 at 11.4. 
. 57 European trees, 1830-1910 at 11. 
4. 
80 European trees, 1800-1910 at 11.4. 
. South Sweden, 1830-1910 at 12.0. 
Vermont group, 1650-1910 at 11.3. 
Flagstaff group, 500 years at 11.4. 
. Flagstaff group at 23.5 years. 
. Norway, 1740-1910 at 23.8 years. 
Austria, 1830-1910 at 22.0 years. 
Norway, N-2, 400 years at 33.0. 
. Vermont, 250 years at 32.5. 
Sweden, 1740-1910 at 37.0. 
. Sequoia, 1300-250 B. C. at 33.0. 
. Flagstaff, 500 years at 33.0. 
o. Sequoia, 3200 years at 101, 
p. Flagstaff, 500 years at 120. 
q. Standard 5-year period at 5.0 years. 
T. 
5to 10 year logarithmic variable 
period at 8.0. 
