18 



BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 



Table 6. — Comparative yields per crop (10,000 cups) toith respect to height of 

 face (inches), 1916 and 19 II. 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 





/ 1916 

 \ 1917 



/ 1916 

 \ 1917 



f 1916 

 \ 1917 



Inches. 

 21.95 

 20.00 



3 12. 85 

 13. 00 



s 23. 67 

 19.00 



38 

 39 



38 

 38 



70 

 72 



Inches. 



0.58 



.51 



3.34 

 .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 









Year. 



Rosin. 



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). 2 





f 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 















Narrow 3 



39.7 

 47.6 



10.5 

 25.0 



-1.1 





Double 3 



+ 5.9 





1 Compiled from monthly field reports for 1916 and 1917. 



2 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 

 doublo faces is 22.20 inches and for the narrow faces 11.38 inches, which, in this 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. 



