76 



THE THEORY AND PRACTICE OF WORKING PLANS 



the time of revision, shows an unintentional increase, the cut 

 was set too low. 



(b) Example. — It is desired to determine the cut of hemlock 

 in the slope type of Catskill forest illustrated by the stand 

 and stock tables quoted above from Bulletin ii of the N. Y. 

 State Conservation Commission.* A breast-high diameter 

 limit of 12 inches is to be observed which, according to U. S. 

 Dept. of Agriculture Bulletin 152, new series, "The Eastern 

 Hemlock," table 10, corresponds to a rotation of 160 years. 

 The current annual increment per cent has been determined 

 from increment borings and Pressler's formula. The com- 

 plete data are as follows: 



D. B. H.. Inches. 



A. I.. Per Cent 

 (Pressler). 



Volume on Average 

 Acre (Stock Table). 



C. A. I. per Acre. 



7 

 8 

 9 

 10 

 II 

 12 



13 

 14 

 IS 

 16 

 17 

 18 



19 



20 

 21 



Per Cent. 

 7.19 



430 

 4.00 

 2.69 

 2.68 



2. 26 



Board Feet. 

 6. J 

 6.4 



•97 

 .89 



17.98 

 24.09 

 28.83 



26.68 

 21.45 

 15-48 

 18.36 

 22.23 

 20.51 

 13.60 



7.78 

 17.56 



> X 



(Cont. in st'k table) 

 See p, 48, 



Total 5. 478 



Board Feet. 

 .488 

 !76 

 ■487 

 .484 

 •645 

 •652 



555 

 376 

 240 

 310 

 329 

 254 

 150 



076 

 156 



To summarize: 



Y 

 Z 



Y+Z- 



^138.31 board feet per acre 

 ^ 168.48 

 306.79 



* Bulletin 11, " Poorest Survey of a Parcel of State Land," Albany, N. Y., 1915, 

 Tables 4 and 5. 



