Forest Mensuration 197 



merits give results accurate enough for most purposes, if 

 the tract is large ; on small tracts — -100 acres and less 

 — all the trees should be measured. If the owner wishes 

 to do the work alone and desires only a rough estimate, 

 he may pace the distances and estimate the diameters of 

 the trees in the strip. He should, however, first measure 

 a number of trees to accustom his eye to accurate 

 estimating. It is best to train the eye in this way every- 

 morning before starting the work. 



There are dozens of such so-called "cruising" methods, 

 and any one of them is fairly accurate for all practical 

 purposes. The one described is, in the author's opinion, 

 the most easily applied to small tracts by the untrained 

 cruiser. The estimator should at the same time note, 

 as nearly as possible, the percentage of loss from crooked 

 and defective trees ; also the average height of the various 

 trees of different diameters. The field work of the valua- 

 tion survey is then complete. It remains to figure out 

 the result from the collected data. 



These records from the different tally sheets are then 

 collected on a single sheet. The totals thus obtained are 

 divided by the number of acres surveyed and the result 

 is an average acre of the whole tract, giving the number of 

 trees of each diameter and species. 



The data seoured from the valuation surveys are worked 

 up in the form of a table giving the number of trees of 

 different diameters in each species on the average acre. 

 This is called a stand table. By means of it the number of 

 trees of different diameters and species on any number 

 of acres on the tract may be calculated. 



