26 BULLETIN 1061, U. S. DEPARTMENT OE AGRICULTURE. 



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 70 per cent over the 

 yield of one face. However, when trees under 12 to 14 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 condi- 

 tion. 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 b} 7 Dr. Charles F. Herty and published by the 

 Forest Service 6 (PI. VIII). To this may be added some results 

 obtained by the Forest Service on the Florida National 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, 46 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 

 follows : First year, 46 barrels ; second year, 38 barrels ; third year, 

 25 barrels ; average yearly, 36.3 barrels. 



This total yield of 109 barrels in three seasons' working with an 

 average yearly production of 36.3 barrels per crop stands in bold 

 contrast to the result of 206 barrels obtained under similar condi- 

 tions on the National Forest by the use of better methods. 



SUGGESTED SYSTEMS OF TURPENTINING. 



A method that is now being tried out on the Florida National 

 Forest in fully stocked second-growth stands starts with the gradual 



8 " Relation of Light Chipping to the Commercial Yield of Naval Stores," by Dr. Charles 

 F. Herty. Forest Service Bulletin 90. For sale by Superintendent of Documents, Govern- 

 ment Printing Office, Washington, D. C Price, 10 cents. 



