TIMBER ESTIMATING. 66 



to judge distances, to note the average height and the diameters 

 of trees, and to guess at their average contents. 



Accuracy in estimating timber depends primarily on this indi- 

 vidual capacity and judgment, and secondarily upon the methods 

 and upon the time which can be given to the work. To obtain the 

 closest possible estimate, three things are essential: First, actually 

 to cover the entire area instead of measuring only a portion of it 

 on the assumption that an average may thus be obtained; second, 

 to count the individual trees instead of merely guessing how many 

 there are on the tract; third, to estimate the actual contents of each 

 I -^ separate tree instead of depending upon an average. Since most 

 estimates must be made hurriedly and at moderate expense, it is 

 seldom possible to obtain this maximum accuracy. Hence the 

 value of the trained cruiser who can substitute his judgment for 

 expensive detailed measurements. The same degree of detail will 

 not always give proportionately accurate results. The smaller the 

 area the more carefully the work must be done, since there is less 

 room for averages and generalizations. 



The larger and more valuable the individual trees the greater will 

 be the care necessary to secure a close estimate. The more varia- 

 tion in the stand due either to topography or to openings the more 

 work is required to get an accurate result. The less skillful the 

 cruiser the more closely must he cover his territory if he desires 

 an estimate which will compare in accuracy with that of a more 

 experienced man. 



* DETERMINATION OF THE CONTENTS OF STANDS, 



Covering the Whole Area. 



Since it is more accurate to cover the entire area than to estimate 

 only a portion of it, timber cruisers endeavor to see all the timber 

 whenever the character of the forest permits. 



ESTIMATE BY THE EYE. 



Formerly nearly all timber cruisers depended solely on their 

 ability to make an approximate estimate of the amount of timber 

 standing on a tract, after a more or less thorough inspection; and 

 timber was so plentiful and cheap that accuracy was not essential. 



♦ Usually the cruisers' guess, based on a superficial examination of 



35450°— Bull. 36—12 5 



