138 ELEMENTARY FORESTRY. 



Putting all these trees in one class, and dividing the total 

 basal area by the number of trees, the mean basal area is found 

 to be .4468, which would correspond to a diameter, at breast 

 height, of nine inches. Selecting a tree nine inches in diameter, 

 it is felled and measured accurately, and the volume found to be 

 11.63 cubic feet. This volume of the sample tree is multiplied 

 by the number of trees, 317, for the total volume on the acre 

 3,686.71 cubic feet. Greater accuracy may be attained by taking 

 a sample tree for each diameter size, and a forest may be meas- 

 ured in miniature by felling and measuring a proportionate num- 

 per of each diameter, say one per cent of each. 



The volume of a sample tree, or of sample trees, is often 

 found by applying the factor of shape, which has been previously 

 determined for that particular species and locality. 



The Conversion of Cubic Feet Total Volume of 

 Standing Timber into Feet Board Measure may be done 

 roughly by considering 1,000 cubic feet as the equivalent of from 

 4,000 to 7,000 feet board measure, according to the size of the 

 trees, young growths giving much less than old growths. 



The Conversion of Cubic Feet Firewood into Cords 

 is accomplished by the use of the factors which experience has 

 shown to be practically accurate. A cord of wood piled up occu- 

 pies 128 cubic feet of space, but on account of the shape of the 

 sticks much of this is air space, and the actual wood content 

 much less than 128 cubic feet. In Germany a cord has been 

 found to contain 83.2 cubic feet of wood. In Saxony Dr. 

 Schenck says that eighty-six cubic feet make a cord of ordinary 

 firewood, and that 25.73 cubic feet of branch stuff will pile up to 

 a cord. At the Minnesota Experiment Station, by actual meas- 

 urement of round, straight sticks, a cord has been found to con- 

 tain as high as 102 cubic feet. This factor of 102 cubic feet may 

 apply very well to straight, well-trimmed spruce, tamarack, etc., 

 free from knots and limbs, but will be too high for oak and 

 similar wood, which is inclined to be more crooked, and does not 

 pile so closely. A cord of small oak averaging 3.4 inches in 

 diameter and ranging from 1.5 to 7.5 inches, consisting of 274 

 four-foot sticks, measured 69.67 cubic feet. Averaging these two 

 extremes, 85.85 cubic feet is found in a cord of mixed wood, cor- 

 responding very nearly to the figure given by Dr. Schenck. 



