Volume Tables. 7 



may be supposed, is a very laborious and time-consuming work. 

 This can perhaps be best appreciated by glancing at the labor 

 involved in the preparation of Baur's volume tables for the Nor- 

 way or European Spruce, published in Munich in 1891. 55,- 

 874 stems of Norway Spruce were carefully measured and their 

 volumes separately calculated. This involved over six million 

 measurements and as many calculations. Then came the great 

 labor of digesting, classifying and preparing the results for publi- 

 cation, which required an additional eighteen months of labor. 

 The great value of such tables, however, has been a sufficient in- 

 spiration to lead to the preparation of such tables for all the com- 

 mercially important species of Europe. These tables are widely 

 used to-day wherever the species for which they were prepared 

 are under careful forest management. 



Volume tables, as already mentioned, are based on a classifica- 

 tion of the stems measured into height, diameter and age classes. 

 The height and diameter measurements are of course fundamental 

 and must be used as factors for classification in any volume table. 

 A classification based on these two factors alone, however, was 

 early found to be insufficient, for great variations in cubic content 

 constantly occur in trees of the same diameter and height. Vari- 

 ous factors cause this variation in the form of the stem, among 

 which might be mentioned age, exposure, soil and climatic con- 

 ditions, altitude and variations in the light conditions obtaining 

 during the growth of the individual trees. 



The exigencies of table-making limit the factors to be used in 

 a classification of data for a single table to two. This may be in- 

 creased to three if the tables are to be a combination of the sim- 

 pler tables, as many tables being necessary as the third factor is 

 given divisions. To introduce a fourth factor as a base of classifi- 

 cation would make the tables so large and complicated that they 

 would be impracticable. 



Recognizing that the two factors, height and diameter, while 

 fundamental, were not sufficient for practical purposes, age 

 classes were chosen as a third factor by all except the most recent 

 workers, and the volume tables for height and diameter classes 

 were computed for each age class (age classes of forty years were 

 usually used). Age was selected from among the various factors 

 as being at once one of the most important factors in influencing 



