Volume Determination 335 



The close coincidence in this species led to the belief that if 

 similar results could be obtained with other species a general vol- 

 ume table might be made based on a formula that would be appli- 

 cable to several or all species. A number of comparisons have 

 been made using from 20 to 100 or more trees of each of the fol- 

 lowing species, with results as indicated. For cedar, results are 

 very close for trees up to 24" in diameter but are too high by 10 

 to 15 per cent for trees over this size. For White pine, spruce, 

 Yellow pine, larch, Lodgepole pine and White fir, average results 

 are within 5 or 6 per cent of actual volume for trees of all sizes, 

 individuals varying in extreme cases up to 15 per cent, but seldom 

 over 6 or 7 per cent. 



Such results for individual trees are closer than can usually 

 be found in using volume tables owing to the variation of indi- 

 vidual trees from the average volume for its size usually caused 

 by different degrees of taper in the lower logs of the tree which 

 contain the greatest volume. For example, two trees having the 

 same D. H. B. and same number of logs may vary two or three 

 inches from having the same taper in the lower logs where the 

 volume is greatest and hence may vary considerably from one 

 another in volume. By basing the rule on the scale of the butt log 

 rather than on D. B. H. this variation is largely eliminated. 



Another advantage possessed by this method is that it makes 

 little difference what diameter is used for the top log as long as the 

 number of logs to this point is correctly used. 



The following examples of Yellow pine trees will illustrate this 

 point: 



Yellow pine 22 inches D.B.H., 5 logs to 6-inch top 



Scale butt log 4- scale top log 



2 X number logs = total scale 



D.I.B. Inches Scale 



First log 18.6 24 Rule Actual 



Second log 16.4 16 24-h2 



Third log 14.5 14 2 ^ ^ - ^^ ^-^ 



Fourth log 11.4 7 



Fifth log 6.0 2 



X 4 = 62 61 



63 



If only 4 logs are cut 24-1-7 



~ 

 If 3 logs are cut 24 + 14 



—2 — X3 = 57 54 



Conversely if the butt log is discarded 16+2 



-^— X4 = 36 39 



