94 FOREST MENSURATION 



not only to determine the board- foot contents of logs but also to 

 measure pulpwood, fuelwood, shingle bolts, distillation wood, poles, 

 piling, cross ties, cooperage bolts, and many other forms of forest 

 products. A timber sealer must be experienced in sawing lumber at 

 the mills in order to estimate the proper deduction to be made for 

 interior defects, such as splits, heart checks, ring shake, butt or heart 

 rot, and pitch streaks. He must also be able to make proper deduc- 

 tion for crook and crotch defects, unsound sap, cat faces, worm holes, 

 lightning scars, frost checks, pitch seams, and other defects which 

 may occur. 



The accuracy of scaling is very largely dependent upon the ex- 

 perience and skill of sealers. 



6. VOLUME TABLES 



A volume table is one which shows the contents in board feet, 

 cubic feet, or other units for a given species of different sizes. For 

 example, from a volume table one may quickly determine that a tree 

 18" in diameter and 120' high contains a stated number of board 

 feet. There are several different kinds of volume tables.* 



7. CRUISING 



Cruising, timber estimating, or land-looking are the terms com- 

 monly used in woods parlance for determining the volume and value of 

 standing timber. A timber cruiser may also make topographic maps 

 used for logging and management plans. For many years, woodsmen 

 of considerable experience were employed, and they generally did a 

 very efficient job. But as timber values rose, a more scientific method 

 became necessary. At first, rough approximations were followed. 

 With low stumpage values, these were sufficiently accurate. In no 

 case, except on the smaller tracts, is all the standing timber actually 

 calipered or measured for height, diameter, and number of trees per 

 acre. Generally a small percentage of the total area is carefully 

 measured and recorded in a tally book. Timber estimating or cruis- 

 ing may be done by ocular or systematic methods. An experienced 

 woodsman can very accurately determine with his eye the diameter 

 and height of individual trees and make a very close estimate of the 

 number of board feet per acre in a given stand. Ocular estimates 

 are still used to some extent. A more accurate and systematic form 

 is actually to measure the height and diameter of all the trees on 



* For further description and analysis, consult the texts referred to. 



