SECTION IV— PRELIMINARY CALCULATIONS 



Explanation. — The object of this section is to give the student sufficient 

 practice in making calculations by means of the various units used in forest 

 mensuration, so that such calculations may be largely dispensed with in suc- 

 ceeding problems wherein they become merely clerical work. 



PROBLEM 12. (Office.) The Determination op the Merchantable Con- 

 tents IN Board Feet of Felled Trees. 



Directions : 



A. Data Required. — Use the tree measurement data collected in Problem 6. 



B. Method of Procedure. 



1, With the aid of a Scribner decimal C log table or scale stick determine 

 the volume in board feet of each log section measured except stump 

 and tip, as shown by the length of the section (log) and the diameter 

 inside of bark at the small end of the section. Round off all diam- 

 eters to the nearest whole inch above or below the actual 

 diameter. In rounding off diameters classify logs with diam- 

 eters exactly half-way between inches (0.5 inch) in the next 

 lower inch. Place all lengths in the even 2-foot length next 

 below the actual size, unless "penalty scaling" is practised in which 

 case place logs which exceed a certain amount allowed for trimming 

 in the sawmill, in the next higher even-foot length. Enter the 

 volumes in the proper columns on the analysis blank. (Form 2A.) 

 Since in the construction of the Scribner decimal C rule the end 

 figure is dropped, add a cipher to the volume of each section as read 

 from the table to secure the full scale of the log to the nearest 10 feet. 



Note. — Where the Scribner decimal C. rule is used for scaling Pacific Coast timber, the 

 maximum scaling length of any section should not exceed 32 feet; i.e., logs up to and including 

 82 feet in length should be scaled as one log, and logs longer than this as two logs of as 

 nearly equal even-foot lengths as possible, the shorter length to be taken nearer the 

 smaller diameter. In this case the diameter at the end of the larger log will be determined in 

 Pacific Coast species by allowing one inch increase for every 10 feet of length for taper; 

 i.e., for lengths from 5 to 15 feet allow 1 inch, for lengths from 16 to 25 feet 2 inches. To 

 illustrate further, a 36-foot log should be broken into two 18-foot sections, and the diameter 

 at the end of the butt section as 2 inches larger than the top diameter at the small end of 

 the whole (36-foot) log. Similarly, a 38-foot log would be broken into a 20-foot section and 

 an 18-foot section, the longer section at the butt end with a diameter 2 inches larger than 

 the top section. 



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