16 
BULLETIN 1064,, U. S. DEPARTMENT OF AGRICULTURE. 
1916 many trees. 36 to 78 per cent, according to the position from 
which the material was taken, showed no decrease in ring width 
following turpentining. Also (see Table 3) 26 to 64 per cent showed 
no decrease in the amount of summer wood formed, and the summer 
wood appears to be one of the most readily affected structural fea- 
tures. In Table 4, covering both 1916 and 1917, similar results 
were shown ; but the decreases in 1917, the second year of the opera- 
tion, are somewhat larger in the case of this type of chipping than 
they were in 1916. The size of the resin passages also decreased 
somewhat as time went on. On the average a greater number of 
resin passages per unit area was formed on this tract in 1917 than 
on the double tract. In both 1916 and 1917, however, the number 
on the narrow tract exceeded that on the standard. 
Table 2. — Comparison of the annual rings formed in round timber (19j.5) and 
turpentined timber (1916). 
Number and kind of speci- 
mens. 
Trees showing increase 
in ring width, 1916 
(percentage of total 
number). 
Trees showing no de- 
crease in ring width, 
1916 (percentage of 
total number). 
Trees showing decrease 
in ring width, 1916 
(percentage of total 
number). 
Chips. 
Incre- 
ments. 
Aver- 
age. 
Chips. 
Incre- 
ments. 
Aver- 
age. 
Chips. 
Incre- 
ments. 
Aver- 
age. 
70 
60 
56 
50 
70 
62 
41 
47 
64" 
36 
58 
95 
82 
78 
76 
95 
73 
57 
67 
36" 
64 
42 
5 
18 
22 
24 
64 
26 
44 
27 
43 
33 
1 The narrow specimens showed more resin centers in the chips than were apparent in the standard and 
double specimens. 
Note.— The increment borings were made on the tree at a distance of 2 to 3 inches from the face and at 
the same height as the last streak. The chips were obtained at the cutting of the last streak. 
Table 3. — Comparison of the amounts of summer wood formed in the round 
timber (1915) and the turpentined timber (1916). 
Number and kind of speci- 
mens. 
Trees showing increase 
in amount of summer 
wood, 1916 (percent- 
age of total number). 
Trees showing no de- 
crease in amount of 
summer wood, 1916 
(percentage of total 
number). 
Trees showing decrease 
in amount of summer 
wood, 1916 (percent- 
age of total number). 
Chips. 
Incre- 
ments. 
Aver- 
age. 
Chips. 
Incre- 
ments. 
Aver- 
age. 
Chips. 
Incre- 
ments. 
Aver- 
age. 
20 trees, untapped 
70 
44 
50 
28 
70 
49 
35 
27 
60" 
26 
38 
75 
70 
64 
44 
75 
65 
45 
41 
40" 
74 
62 
25 
30 
36 
56 
25 
50 trees, narrow J 
54 
35 
50 trees, standard 
50 trees, double 
20 
26 
55 
59 
i The narrow specimens showed more resin centers in the chips than were apparent in the standard and 
double specimens. 
Note.— The increment borings were made on the tree at a distance of 2 to 3 inches from the face and at 
the same height as the last streak. The chips were obtained at the cutting of the last streak. 
