72 LOBLOLLY OR NORTH CAROLINA 1". 



YOU .MK TABLES. 



Table 23 gives the volumes of both upper and lower logs of different 

 diameters, measured inside the bark at the small end of the log, in (1) 

 cubic feet; (2) by Doyle-Scribner rule; (3) band-sawed 1-7 inch kerf; 

 (4) circular-sawed 1-4 inch kerf; and (5) the number of board feet ob- 

 tainable per cubic foot of solid wood, mill factor. 



The saw gain of logs from the upper part of the tree over logs from 

 the lower part of the tree is noteworthy. This is due to the greater 

 actual volume in cubic feet of the top logs on account of their taper, the 

 volume being calculated on the basis of the average diameter at the 

 small end. The number of board feet per cubic foot shows that even 

 in converting a tree 14 inches in diameter breasthigh with a band saw 

 1-7 inch kerf, more than one-half of the volume of wood in the logs is 

 lost in kerf, shrinkage, and slabs. Even in a tree with a diameter of 30 

 inches, the average diameter of logs being 18 inches, this loss exceeds 

 one-third of the volume of the cubic contents of the logs. 



Tables 24 to 31 give the merchantable volumes in board feet of trees 

 of different diameters and heights in actual mill tallies and in Scribner 

 Decimal C, Doyle-Scribner, and Tiemann log rules. The volume tables 

 based on the actual mill cut are both for logs band-sawed with seven cuts 

 to the inch and for logs sawed with a circular saw with four cuts to the 

 inch. Trees less than 50 years old will yield less than the volumes 

 given in Tables 24, 26, 28 and 30; in stands 40 to 45 years old about 

 10 per cent less; in stands 30 to 40 years old about 15 per cent less. 

 The actual volume of trees in a 45 year old stand is shown in a footnote 

 to Table 26. This is the actual cut at the mill. 



The volume as given in Tables 24 to 31, inclusive of Table 30a, is 

 based on straight logs or crooked logs in which the crook amounts to 

 less than 2 inches in a 16-foot log. The rule is to scale down into an 

 inch lower diameter class logs which have about this degree of crooked- 

 ness. In about 30 per cent of the logs cut, the crook amounts to more 

 than 2 inches. There is little loss in the cut from crook, however, until 

 the crook amounts to more than one-fourth of the diameter of the log, 

 which will seldom occur in trees more than 12 inches in diameter. No 

 allowance is made in these tables, or in the tables based thereon, for 

 crooks which exceed 2 inches, for waste, which is often 5 per cent (see 

 footnote to Table 26), or for breakage. In ordinary calculation of 

 volume, estimating, or of yield a deduction, which will vary with the 

 class of timber and the locality, should be made for losses from these 

 sources. On poor sites the deduction for crook may amount to 6 per 

 cent (Plate XII) ; on good sites it may not exceed 2 per cent. With 

 careful felling and cutting the loss from breakage should be less than 

 one-half of one per cent. A comparison of Table 26 with the table in 

 the footnote shows that in an average operation a deduction of 25 per 

 cent should be allowed from the mill cut volumes given for 6, 7, and 8- 



