26 BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 



of chipping surface or working face (about 32 streaks) was allowed 

 in any one chipping season, so that the operator was at liberty to 

 use more streaks, provided they were less than one-half inch high. 

 (PL VII, fig. 4.) 



This method was found to give satisfactory and sustained returns 

 even over periods of six or more years. Indeed, timber owners in 

 the vicinity who observed the results thus secured voluntarily aban- 

 doned the heavier chipping which they had previously practiced in 

 favor of this method. The question of whether the height of chip 

 used could advantageously be reduced somewhat further — as the 

 results of the narrow chipping at Columbia, Miss., indicated might 

 be the case, at least on the timber of that section — is one needing 

 immediate attention. The yield from the narrow chipping did not 

 show appreciable reduction during the second year, as was generally 

 the case with the crops operated by the standard Forest Service 

 method. 



EXPERIMENTS ON THE FLORIDA NATIONAL FOREST. 



Very interesting results have been obtained by experiments made 

 on the Florida National Forest near Camp Pinchot in an effort to 

 find a system for working longleaf pine that would produce (at the 

 same cost or, if possible, at smaller cost than that which now is 

 customary in ordinary practice) as high an immediate yield of 

 gum as is now obtained, and also a good sustained yield for a 

 longer period. Some of the methods tested are illustrated in Plate I, 

 figures 5 and 6. Special attention was given to finding a method 

 adapted to application on relatively small, young, second-growth 

 timber. A striking illustration of the effect of heavy as compared 

 with conservative chipping on wood formation and general tree 

 responses was observed when some material from the tract on which 

 the French method of turpentining was being used was compared 

 with specimens from very heavily chipped trees from the same 

 locality on a private tract. Figures 5 and 6, Plate VI, illustrate 

 the relative effects of these methods. Both specimens were cut on 

 May 6. 1916. At that time practically no wood cells had been differ- 

 entiated in the case of the heavily chipped tree (streak three- 

 fourths inch or more deep and three-fourths to 1 inch in height), 

 whereas a considerable number of wood cells and a number of resin 

 passages had formed in the specimens from the French-chipped area. 

 (PI. VI, fig. 6.) Moreover, in this latter specimen the ring width 

 and the amount and density of the summer wood formed after tur- 

 pentining were not reduced, as compared with the conditions found 

 in the round timber. In the case of the heavy chipping, however, 



