How Trees are Measured 

 MEASURING DIAMETER 



A tree's diameter is measured by calipers, which consist 

 of a graduated rule, marked in inches and fractions, a fixed arm 

 forming a right angle at one end, and a movable arm, parallel 

 with the first one, sliding on the rule. The rule is set against a 

 tree above the bulge of the base. The fixed arm touches it at 

 one point, and the sliding arm comes up to a point on the bark 

 diametrically opposite. The base of this arm indicates the 

 diameter of the tree on the scale of inches. 



Logs and standing timber are measured by this tool. Calipers 

 for ordinary work have rules four to five feet long. Few trees 

 require longer ones. 



MEASURING VOLUME 



Standing trees are assumed to be regular geometrical solids, 

 resting on a circular base and tapering to the limbs, a compromise 

 between a cone and a cylinder. 



To get the solid contents of a trunk, the area of the base is 

 multiplied by one-half the altitude. With a pair of calipers 

 and any one of the four methods of obtaining the tree's height 

 its cubical contents are easily computed. The forester cannot 

 stop to multiply and compute the circular base on which the tree 

 rests. He uses a table where these are worked out. 



Timber is measured in board feet oftener than by volume. 

 A board foot is a foot square and one inch thick; there are twelve 

 board feet in one cubic foot. It is generally estimated that one- 

 third to one-half of a log is sawdust, slabs and defective wood. 

 Allowance is therefore made for these losses. Much depends 

 upon how the logs are sawed. 



A "cruiser" was an old-time woodsman who went into the 

 forest with a compass, and, pacing off the distances, located and 

 estimated the timber in tracts with obscure boundaries. Once 

 is was saw stuff only that he calculated. Now not only sawlogs, 

 bi't ties and poles and fuel are taken account of in these estimates. 



By tables known as "Log Scales" the number of feet, board 

 measure, a given tree will yield is quickly found. Height and 

 diameter being known, the table gives the contents. In measuring 

 standing timber it is customary for two measurers to go ahead 



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