28 



BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 



Table 7. — Early Forest Service experiments — Summary of total yields for 

 1905, 1906, 1907. and 1908 on tlie basis of the corrected amounts of dip and 

 scrape (125 drippings). 



[Data from U. S. Department of Agriculture, Forest Service Bulletin 90.] 



Crop. 



Dip (oleoresin). 



Yield. 



Scrape (hardened 

 oleoresin). 



Yield. 



In- 

 crease. 



De- 

 crease. 



Total 

 num- 

 ber of 

 chip- 

 pings. 



Aver- 

 age 

 height 



of 

 chip- 

 pings. 



Average 

 depth of 

 chip- 

 pings. 



Dead 

 trees 



at 

 end of 

 sec- 

 ond 

 sea- 

 son. 



Per cent of 

 stand. 



Long 

 leaf. 



Slash. 



A. Standard chipping 

 of Wallrill Turpen- 

 tine Co. 1 



B. Shallow chipping. 



C. Narrow chipping.. 



D. Reduced number 

 of faces, larger trees, 

 prospect of back 

 cupping 3 



206, 235 

 211,911 

 21-1, 503 



279, 260 



2.75 

 4.01 



47, 742 

 44, 838 

 39, 775 



Indies. 



0.51 



.51 



.40 



Inches. 

 2 0.7 to 0.6 

 2 0.4 to 0.3 

 2 0.7 to 0.6 



2 0.7 to 0.6 



1 Minimum diameter of turpentined trees 6 inches, 2 faces permitted on trees over 13 inches. 



2 Shallower cuts on slash. 



3 Minimum diameter of turpentined trees 10 inches, 2 faces permitted on trees over 16 inches. No more 

 than 2 faces per tree. 



A summary of the results obtained is given in Table 7. It is ap- 

 parent that crop* A (standard) showed a successive yearly decrease 

 in yield and the greatest number of dry-faced and dead trees. 



Crop B, the shallower chipping, showed in the four years of oper- 

 ation an increase in yield of about 3 per cent over the standard. 

 This gain took place during the last two years of the operation. 

 There was less relative yearly decrease in yields also than in crop A, 

 and less scrape was formed, which fact, the writer pointed out, was 

 in accord with the current idea that deep chipping produced much 

 scrape. From these results it is concluded in Bulletin 90 that there 

 is " no doubt as to the wisdom of shallow chipping." 



In sharp contrast to this were the results from an operation visited 

 in 1917 in Mississippi. The type of timber and the method of chip- 

 ping employed are illustrated in Plate VII, figures 5, 6, and 8. The 

 streak cut was about 0.75 to 1 inch in depth and a scant 0.5 inch in 

 height, and a very high as well as a sustained yield was reported. 27 

 These trees were characterized by having very wide sapwood. Less 

 than 1 per cent of the trees were lost through death from turpentin- 

 ing. Care and good judgment were exercised in the placing of the 

 cups and in maintaining adequate bark bars between the faces on 

 this timber. 



It would appear from the foregoing that the question of the width 

 of the sapwood and the responsive vigor of the timber on any given 

 tract must be considered as of fundamental significance in determin- 

 ing the depth of the streak to be cut. That the resin passages in a 



27 Reported yield of 105 barrels- of turpentine per yearling crop and an average of 82 

 barrels for different ages, including virgin and fourth-year workings. 



