30 BULLETIN 1061, U. S. DEPARTMENT OF AGRICULTURE 
trees ranged from 7 to 12 inches in diameter (measured at breast- 
height, or 41/9 feet above the ground) : each tree was hung with one 
cup and was being worked for the first year. The production for 
the season is computed on the assumption that there were six 
dippings. 
The most noteworthy point here is that a 7-inch tree yields only 
about one-half the gum yielded by a 10-inch tree. The 10, 11, and 
12 inch trees with 2 cups yielded 50 per cent more gum than trees 
of the same sizes worked with only 1 cup each. In operations on 
small timber the expense of cups, hanging, chipping, and dipping 
is incurred in connection with many trees that yield only about a 
quart of gum for a full season's working. Even smaller returns 
than those shown above are not uncommon. In May. 1920. third- 
year workings of these small sizes were found that yielded at the 
rate of 1 ounce of gum to each four streaks. The conclusion arrived 
at from these weighings is that, in general, timber less than 8 inches 
in diameter at breastheight. or about 10 inches on the stump, yields 
gum in such small amounts as to be considered below a workable 
size. 
Faces per tree. — Observations on virgin crops indicate that the 
addition of the second face, when conservatively made and worked 
on longleaf pine trees from 10 to 12 inches in diameter at breast- 
height, increases the yield of the tree by about 50 per cent over the 
yield of one face. However, when trees under 12 to 11 inches in 
diameter have been worked with a second face their growth has nearly 
stopped. They have often been found to be in a sickly or dying con- 
dition. The more observing and practical operators feel justified for 
that reason in not permitting a second face on trees less than 15 inches 
in diameter: but if a second face is allowed, they require that bars 
shall measure at least 4 inches across and that at least 40 per cent of 
the surface or circumference of the tree shall remain uncut. 
Heavy chipping. — For conclusive results regarding the effect of 
heavy and light chipping, reference may be made to the experiments 
carried on in Florida by Dr. Charles F. Herty and published by the 
Forest Service 6 (PL VII). To this may be added some results 
obtained by the Forest Service on the Florida Xational Forest near 
Pensacola. In these workings the trees were conservatively cupped, 
and chipping was limited to one-half inch in depth and the same in 
height. Under these conditions the results per crop of 10.000 cups 
from five successive years' work on a specified body of timber have 
been as follows: First year. -16 barrels: second year. 40 barrels: third 
year. 41 barrels: fourth year, 38 barrels: fifth year. 41 barrels. 
The average season's production of gum per crop was. therefore, 
41 barrels, with a total of 206 barrels. It will be noted that there 
was a slight alternation in the amounts, with production the third 
and last years equal to the average for the operation. A significant 
result was the subsequent death of only 2 per cent of the trees from 
dry facing. Private operations in the same locality using the ordi- 
nary old-time system commonly lose from 10 to 20 per cent of their 
timber and the average yield of gum obtained is approximately as 
3 '• Relation of Light Chipping to the Commercial Yield of Naval Stores." by Dr. 
Charles F. Herty. Forest Service Bulletin 90. For sale by the Superintendent of Docu- 
ments, Government Printing Office, Washington, D. C. Price, 10 cents. 
