BLACK WALNUT! ITS GROWTH AND MANAGEMENT. 29 
Table 10. — The Doyle log rule. 
Length in feel. 
Diam- 
eter 
in 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
inches. 
Board feet. 
6 
1.5 
1.8 
2.0 
2.3 
2.5 
2.8 
3.0 
3.3 
3.5 
3.8 
4 
7 
3.4 
3.9 
4.5 
5.1 
5.6 
6.2 
6.8 
7.3 
7.9 
8.4 
9 
8 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
9 
9 
11 
12 
14 
16 
17 
19 
20 
22 
23 
25 
10 
13 
16 
18 
20 
22 
25 
27 
29 
31 
34 
36 
11 
18 
21 
24 
28 
31 
34 
37 
40. 
43 
46 
49 
12 
24 
28 
32 
36 
40 
44 
48 
52 
56 
60 
64 
13 
30 
35 
40 
46 
51 
56 
61 
66 
71 " 
76 ' 
81 
14 
37 
44 
50 
56 
62 
69 
75 
81 
87 
94 
100 
15 
45 
53 
60 
68 
76 
83 
91 
98 
106 
113 
121 
16 
54 
63 
72 
81 
90 
99 
108 
117 
126 
135 
144 
17 
63 
74 
84 
95 
106 
116 
127 
137 
148 
158 
169 
18 
73 
86 
98 
110 
122 
135 
147 
159 
171 
184- 
196 
19 
84 
98 
112 
127 
141 
155 
169 
183 
197 
211 
225 
20 
96 
112 
128 
144 
160 
176 
192 
208 
224 
240 
256 
21 
108 
126 
144 
163 
181 
199 
217 
235 
253 
271 
289 
22 
121 
142 
162 
182 
202 
223 
243 
263 
283 
304 
324 
23 
135 
158 
180 
203 
226 
248 
271 
293 
316 
338 
361 
24 
150 
175 
200 
225 
250 
275 
300 
325 
350 
375 
400 
25 
165 
193 
220 
248 
276 
303 
331 
358 
386 
413 
441 
26 
181 
212 
242 
272 
302 
333 
363 
393 
423 
454 
484 
27 
198 
231 
264 
298 
331 
364 
397 
430 
463 
496 
529 
28 
216 
252 
288 
324 
360 
396 
432 
468 
504 
540 
576 
29 
234 
273 
312 
352 
391 
430 
469 
508 
547 
586 
625 
30 
253 
296 
338 - 
380 
422 
465 
507 
549 
591 
634 
676 
31 
273 
319 
364 
410 
456 
501 
547 
592 
638 
683 
729 
32 
294 
343 
392 
441 
490 
539 
588 
637 
686 
735 
784 
33 
315 
368 
420 
473 
526 
578 
631 
683 
736 
788 
841 
34 
337 
394 
450 
506 
562 
619 
675 
731 
787 
844 
900 
35 
360 
420 
480 
541 
601 
661 
721 
781 
841 
901 
961 
36 
384 
448 
512 
576 
640 
704 
768 
832 
896 
960 
1,024 
37 
408 
476 
544 
613 
681 
749 
817 
885 
953 
1,021 
1,089 
38 
433 
506 
578 
650 
722 
795 
867 
939 
1,011 
1,084 
1,156 
39 
459 
536 
612 
689 
766 
842 
919 
995 
1,072 
1,148 
1,225 
40 
486 
567 
648 
729 
810 
891 
972 
1,053 
1,134 
1,215 
1,296 
forests, in which all or many of the species are to be logged together, 
but by the separate examination of each merchantable tree. The 
usual practice is to estimate first the length and small-end diameter 
inside the bark of each log in the tree, and then to find the contents 
of the logs in board feet by the Doyle rule. To estimate closely the 
length and taper of the logs and their diameters inside the bark re- 
quires a practiced eye and a knowledge of bark characteristics, in 
order that the thickness may be gauged from appearances with rela- 
tive accuracy. In most merchantable logs the bark averages from 1 
to \\ inches in thickness, as shown in Table 11. 
Table 11. — Thickness of dark, in inches, on logs of different diameters. 1 
Diameter 
Bark 
Diameter 
Bark 
Diameter 
Bark 
of log. 
thickness. 
of log. 
thickness. 
of log. 
thickness. 
6 
0.5 
15 
1.1 
24 
1.3 
7 
.5 
16 
1.2 
25 
1.4 
8 
.6 
17 
1.2 
26 
1.4 
9 
.7 
18 
1.3 
27 
1.4 
10 
.8 
19 
1.3 
28 
1.4 
11 
.9 
20 
1.3 
29 
1.4 
12 
1.0 
21 
1.3 
30 
1.4 
13 
1.0 
22 
1.3 
14 
1.1 
23 
1.3 
Based on 291 logs mostly from Ohio and Indiana. 
