THE CONSTRUCTION OF A TAPER TABLE 37 



C. References. — Numbers 33, 34 and 40. 



D. Discussion. 



1. What is gained over Method I by using IVIethod II? 



2. Compare the frustum form factor method and the regular method of 



constructing volume tables as to time required and as to accuracy. 



3. How might the table bo constructed by averaging according to the 



number of 16-foot logs as well as according to D.B.H. as explained 

 in Method H? 



PROBLEM 20. (Office.) The Construction of a Taper Table. 



Expl.\nation: Taper Tables show for each D.B.H. the top diameter inside 

 the bark of the respective 16-foot logs (the usual length employed). Such 

 tables can be used in place of volume tables in cruising where the trees are 

 tallied according to the D.B.H. and number of 16-foot logs. This method 

 has an advantage over volume tables in that an estimate can be worked up 

 according to any log rule or any one of the units of log measure. It presents 

 the disadvantage of requiring more subsequent calculations for securing the 

 volume of an estimate than does the use of volume tables. 



Directions: 



A. Data Required. — Use data collected in Problem 6. 



B. Method of Procedure. (Prerequisite study — Reference Number 38.) 



1. On a separate sheet of cross-section paper for each 20-foot total height 



class, lay off heights above the ground as abscissae and diameters 

 inside of bark as ordinates. 



2. Plot all trees in 2-inch D.B.H. classes. 



3. For each D.B.H. class plot points representing the D.I.B. at the top 



end of each 16-foot log section. If possible, plot all curves on one 

 sheet using a different symbol (., x, o, O,) for each diameter class in 

 order to keep the various classes separate. 



4. Average points for each 16-foot section of each D.B.H. class, and 



construct regular curves for each D.B.H. class. 



5. Assume an arbitrary stump height (e.g., 3 feet), and read off the D.I.B. 



values for each 16-foot section. 



6. For the same 20-foot total height classes and u^ith the same ordi- 



nates but using D.B.H. for abscissae, replot and average the data 

 in separate 16-foot classes above the stump. 



7. From the averaged data found in 6, for each 2-inch D.B.H. class plot 



a series of 16-foot curves above the stump, using the same ordi- 

 nates and the total heights of trees as abscissae. 



8. With the averaged data from 7 now plot a fourth set of curves 



exactly as was done in 1 and then, with the data thus obtained, 

 plot a fifth set of curves as was done in 6. Retain the data thus 

 obtained in graphic form or read off a set of tables. 



