52 FOREST RJvGUI,ATION 



material, and the costs to one or few per cents and be certain of his 

 figures, then why cannot you do the same ?"' 



JJut if the engineer's material were scattered promiscuously over 

 miles of country, and no two pieces alike, and none of any accurate 

 geometrical figure, none in position to weigh or actually measure, 

 he would probably prefer not to estimate at all. 



Generally, ten per cent must be regarded as an attainable, and 

 also a satisfactory accuracy in forestry estimates of volume. In 

 most forestry work the estimate of the merchantable stuff is not 

 used as final measure ; the logs are scaled when cut, and it is usually 

 far more important to have a good description, to record the condi- 

 tion of the forest on a particular forty than to try for great accu- 

 racy in the estimate of Volume. 



II. SPECIAL STUDIES IN THE FOREST. 



In the examination of large wildwoods properties it is usually 

 desirable, almost necessary, to add the following : 



a. Preparation of Volume Tables of the important kinds of 

 timber ; 



b. Preparation of Yield Tables ; 



c. Study of the Behavior of the important species, and the in- 

 juries of the recent past as well as the principal points of danger; 



d. Special study of conditions not really of the forest, such as 

 grazing lands, camping grounds for tourists ; peat, gravel rock de- 

 posits, etc., which may, in time, become sources of income. 



a. Volume Tables. 



These tables give the volume of the individual tree and are 

 usually of two kinds, one based on diameter breast high, the other 

 on the age of the trees. 



I. The tables based on diameter state that a tree 12" d. b. h. 

 14", 16", etc., contains a certain volume, either in cubic feet or feet 

 board measure. They are useful, primarily, in the computation of 

 the results of estimates or caliper measurements as made during the 

 survey, but they give no information as to the rate of growth of the 

 tree. To be of use for the timber on different sites (soil or altitude) 



