30 



BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 



and too numerous faces, which unduly reduce the relative percentage 

 of uncut bark, are unquestionably harmful and unprofitable. The 

 questions of depth and height of streak are intimately connected with 

 the number of faces and the returns obtained, but further work is 

 needed, as has been shown, to fix within narrower limits the range 

 of the most successful depth and height of chipping. It is stated 

 by careful operators that, at the very least, one-third of the bark 

 should remain uncut, and undoubtedly a larger proportion is de- 

 sirable. The area D at Walkill was so turpentined that it would be 

 possible to work it for a second period (back cup) some time later. 



Table 8. — Yield at first clipping from trees of different diameters. 





Set 1. 



Set 2. 



Diameter breast high 

 (inches) . 



Width of 



face 

 (inches). 



Yield 



(average 



of 15 



trees). 



In pea- 



centage 



of 10-inch 



trees. 



Yield. 



5 





Ounces. 





Ounces. 

 4 



6 











7 



7 



8 



9 



9i 

 10 

 10 



10 



15 



19 



22J 



23 



24 



44 

 67 

 84 

 100 

 102 

 i 107 



8J 



11 



14 



164 



19 



21 



8 



9 



10 



11 



12 





1 4 trees. 



Table 9. 



-Gain obtained by light cupping as compared with Standard chipping 

 at Walkill, Fla. a 





Dip. 



Increase. 



Last three years compared to first. 



Year. 



A, stand- 

 ard. 



D, light- 

 cupped. 



Pounds. 



Per cent. 



A 



D 





Increase. 



Decrease. 



Increase. 



Decrease. 



1905 



Pounds. 

 63,615 

 64, 583 

 43, 675 

 34, 362 



Pounds. 

 73, 704 

 84,074 

 69, 286 

 52, 196 



10, 089 

 19, 491 

 25,611 

 17,834 



16 

 30 

 58 

 52 











1906 



6 1| 





b 14 





1907 



31 



46 



g 



1908 







29 











a For. Serv. Bui. 90, p. 20. 



b This increase was chiefly due to the fact that in 1905 there were 31 streaks and in 1906, 35 streaks cut. 



Because of the gains secured in the first three years of the Walkill 

 experiments, a different experiment was instituted on two crops 

 during the fourth year (1908), which combined both the shallow 

 and the narrow chipping features. " Yearling " or second-year 

 crops were used, and the yields of gum were compared with those 

 from a similar adjacent crop chipped by the standard method. An 

 increased production of about 35 to 38 per cent was secured in this 

 experiment. The " dip " from these shallow and narrow-chipped 



