OLEORESIX PRODUCTION. 29 
considerable number of the outer sapwood rings are involved in the 
yields of gum obtained is evident from the discussion on pages 9 
and 10 and from Plate III, figure 2. 2S It would therefore appear 
that the proportion of the sapwood which it is desirable to expose 
in chipping probably varies somewhat according to circumstances, 
and that the range of depth should be more exactly determined by 
further experiments on different types of longleaf and slash pine 
timber, especially on young timber, since this is of great future 
significance. 
Crop C, the narrow chipping, did not have as narrow streaks as 
those cut at Columbia, Miss. Although it was intended that the 
streaks should be about one-fourth inch in height, it is stated that " in 
spite of continued urging and the closest supervision, the chippers in- 
variably made the cut wider than was desired. * * * Neverthe- 
less in spite of the failure to reduce the width of the cut as much 
as desired, a considerable decrease was made." The height of the 
faces at the end of 4 years on crop A (standard) was 6-1.3 inches, 
and on C, 50 inches, or an average height of chip of about 0.4 inch. 
Under the narrowed chipping this crop showed an increase over the 
standard which was greater than that secured by the shallow chip- 
ping of crop B. Furthermore, less dry-face and dead trees resulted, 
and about one year of chipping surface (14.3 inches) was gained. 
These facts, therefore, furnish another instance of successful narrow 
chipping. How far the streak can further be narrowed with ad- 
vantage beyond this 0.40 inch and the 0.34 inch obtained at Columbia, 
Miss., and sometimes obtained in commercial " pulling," is a subject 
for further experiment. 
Crop D, the light cupping at Walkill, Fla., where fewer faces were 
cut per tree and no tree under 10 inches was cupped, but where the 
standard streak was cut, gave the highest yield of all the crops and 
the least loss from dry-facing or death of trees. It should be borne 
in mind that on the other crops trees with a diameter as small as 6 
inches were cupped, and two faces were permitted per tree on timber 
with a diameter of 13 inches and over. (See Table 7.) As has been 
recently shown, it is unprofitable from the point of view of the 
growth in length and diameter of the timber, as well as from that of 
the yield of gum. to turpentine too small trees by the methods gen- 
erally practiced in the United States. 29 (See Table 8.) 
It was demonstrated clearly both in the Walkill experiment and in 
Cary's observations (Table 8) that it was of fundamental importance 
to maintain the vitality and responsive power of the tree. Too large 
28 This fact was not recognized at the time that the conclusion in regard to shallow 
chipping was expressed in Forest Service Bulletin 90. 
29 Cary, Austin. "A look ahead " in Naval Stores, published by the Weekly Naval Stores 
Review, and in " Money is actually lost in working small trees for turpentine and rosin." 
Naval Stores Review and Trade-Journal. Vol. XXX, Jan. 22, 1921, p. 14, and Nov. 19, 
Dec. 3, 10, 24, and 31, 1921, and Jan. 7 and 14, and Feb. 4, 1922. 
