64 THE WOODSMAN'S HANDBOOK. 



Even when used in very irregular stands, where the trees differ 

 largely in age and development of crown, such tables are more accu- 

 rate than volume tables based on diameter alone. 



Volume tables based on diameter and height have been con- 

 structed for several species in this country and used in the practical 

 work of estimating. They give good results with trees of regular 

 form like the pines and spruces, but with the hardwoods they are 

 not entirely satisfactory .unless separate tables are made for different 

 tree classes. 



Volume tables may be made for poles, and it would* be of great 

 practical value to have tables showing the average length and top 

 diameter of poles yielded by chestnut of different diameters, or 

 the length and middle diameter of piles contained in pitch pines 

 of different sizes. 



The purpose of studying the volumes of single trees is to facilitate 

 the compilation of the contents of stands. Occasionally a single 

 tree is sold, and a knowledge of its volume is desired, but ordinarily 

 the single tree is of interest to the woodsman only as it forms a part 

 of a whole stand or forest. 



Factors that Affect the Accuracy of Estimates. 



Different methods of estimating the contents and value of timber 

 have been developed in various parts of the country. These 

 methods differ in degree of accuracy of results and each is designed 

 for a particular region and set of conditions. Each timber cruiser 

 has his own peculiar method of estimating the contents of a stand 

 of trees. With many the general principle of procedure is the 

 same, but the actual application varies. The reason for this is that 

 accuracy is not so much a matter of method as of judgment, which 

 can be acquired only through practical experience and training. 

 Therefore it is not possible to learn from books how to estimate 

 timber, though a discussion of the various general methods of work 

 should prove helpful. 



Standing timber nearly always contains defects. Allowance is 

 made for these defects in various ways, but the cruiser must be 

 able to detect the outward signs of defects, and, from his general^ 

 knowledge, must decide what percentage of the timber is sound. 

 The personal training of the cruiser also enables him to use his eye 



