330 JOURNAL OF FORESTRY 



and ridges and increasing it, even up to 100 per cent, in the hollows 

 in which heavier stands are located. In open timber it is not difficult 

 to do this by chaining with care or sometimes by blazing the outer lines 

 of the areas subjected to the more intensive cruise; in places, however, 

 where undergrowth such as laurel or ivy is heavy, considerable difficulty 

 is encountered in locating. A very careful chaining and close com- 

 pass work is necessary to prevent much loss of time and the possibility 

 either of skips or overlaps. In the case of tracts smaller than 100 

 acres a 100 per cent cruise is as a rule desirable and even necessary in 

 order to insure accuracy. 



The Determination of Grades and Defects. 



In all cases stumpage values for each species are worked back from 

 the mill-run grades of lumber. The determination of stumpage values 

 from the per cent of the different grades of lumber which the timber 

 will yield is complicated on account of the large number of species, and 

 this complication is increased not only by reason of great variation in 

 the size of timber on different tracts and sometimes on portions of the 

 same tract, but also in many cases as a result of past culling having 

 removed a considerable portion of the prime trees. General grade 

 yields averaged from several mills are not applicable to particular 

 tracts and it is equally inept to employ the grade yield of a nearby 

 mill for a tract unless a careful examination of both tracts shows that 

 the quality of the timber is the same. Mere propinquity is not sufficient 

 to insure equal grade and value, though often relied on. The grade 

 yield of lumber on each tract should be ascertained from the grades of 

 logs in the standing trees with the same thoroughness as the volume. 

 The best checks on the appraiser's field calculation of the per cent of 

 grade volume tables for different species. Grade volume tables, how- 

 ever, are not infallible and must be so prepared as to be applicable for 

 different conditions ; that is, they must be based on quality sites as well 

 as on diameter and age classes, thus requiring several tables for each 

 species ; and it must be possible to correlate the conditions under con- 

 sideration with the appropriate grade volume table. Grade volume 

 tables can be applied, however, only to normal, sound stands, and 

 Appalachian stands are often aberrant. 



There is little difficulty in making appropriate allowance for visible 

 defect. Each tree showing it is discounted as tallied and it is in meeting 



