18 
BULLETIN 1064, U. S. DEPABTMEXT OE AGBICULTUBE. 
Table 6. — Comparative yields per crop (10 MO cups) tenth respect to height of 
face (inches), 1916 and 191'7. 1 
Year. 
Height 
of face. 
Num- 
ber of 
streaks. 
Average 
height 
of 
streak. 
Turpentine. 
Plot. 
Total 
yield 
per 
crop. 
Yield 
per inch 
of face 
height. 
Increase 
in per- 
centage 
(stand- 
ard 
rated 
100 per 
cent). 
Comparison of 
percentage 
(year 1916 
rated 100 per 
cent). 2 
Standard 
J 1916 
\ 1917 
/ 1916 
\ 1917 
/ 1916 
\ 1917 
Inches. 
21.95 
20.00 
3 12.85 
13.00 
3 23. 67 
19.00 
38 
39 
38 
38 
70 
72 
Inches. 
0.58 
.51 
s.34 
.34 
3.34 
.26 
Gallons. 
3,704 
3,046 
3, 035 
2,946 
4,248 
3,613 
Gallons. 
169 
152 
236 
227 
179 
190 
39.6 
49.4 
5.8 
25.0 
100. 00 
90.00 
100.00 
96.2 
100.00 
106.2 
Narrow 3 
— 10.0 
Double 3 
— 3.8 
+ 6.2 
Y^ear. 
Eosin. 
Plot. 
Total 
yield 
per crop. 
Yield 
per inch 
of face 
height. 
Increase 
in per- 
centage 
(stand- 
ard rated 
100 per 
cent). 
Comparison of per- 
centages (year 1916 
rated 100 per cent). 3 
/ 1916 
\ 1917 
/ 1916 
\ 1917 
/ 1916 
\ 1917 
Pounds. 
119, 929 
102, 334 
98, 073 
98, 176 
142, 932 
121, 424 
Pounds. 
5,463 
5,117 
7,632 
7,552 
6,039 
6,391 
100 
93.5 
100 
98.9 
100 
105.9 
Standard 
39.7 
47.6 
10.5 
25.0 
Narrow 3 
— 1. 1 
Double 3 
+o. 9 
1 Compiled from monthly field reports for 1916 and 1917. 
J Minus ( — ) indicates loss; plus ( + ) indicates gain. 
3 The narrow and double areas had four standard streaks before the experiment started. The height 
of the four streaks averaged 2.75 inches (average from 25 measurements). With this allowance, the streaks 
on the narrow and double areas averaged 0.30 and 0.32 inch, respectively. The corrected height for the 
double faces is 22.20 inches and for the narrow faces 11 .3S inches, which, kTthis latter case especially, would 
further improve its rating. 
The comparative yields obtained are given in Tables 5 and 6. It 
is apparent that the total yield from the 1916 chipping was highest 
in the case of the double tract and lowest in that of the narrow. If, 
however, the narrow is compared to the standard with reference to 
height of face chipped, it is apparent that the narrow shows a gain 
of almost 40 per cent in the first year of the operation. During 
1917, the second year of chipping, the results were even more strongly 
emphasized. The double showed about the same increase in total 
yield over the standard, but the narrow made a better relative show- 
ing than the year before, and nearly equaled the standard in total 
yield. With reference to the height of face, i. e., amount of chipping 
surface used to obtain the yield, the narrow showed almost a 50 per 
cent gain over the standard in yield per inch of height of face 
chipped. 
