mum length of 8 feet. The surface does not need to be 

 clear, but at least 50 percent of the volume must be sound. 



Log Rules 



Tree Classification 



Good sawlog-size tree. — A pine or cypress tree at least 9 

 inches d. b. h., or hardwood tree at least 13 inches d. b. h., 

 which will produce one sound butt log at least 12 feet long, 

 or which contains at least 50 percent of its gross volume in 

 sound material in case this butt log is a cull. 



Good under-sawlog-size tree. — Any tree between 1 inch and 

 the minimum merchantable diameter at breast height, 

 with not more than 25 percent rot and a reasonably straight 

 stem. 



Sound cull tree. — A tree which, because of form, crook, 

 extreme limbiness, or other sound defect, is not and never 

 will become suitable for saw timber. 



Rotten cull tree. — A sawlog-size tree that is over 50 percent 

 defective, or an under-sawlog-size tree that is more than 

 25 percent defective. 



Doyle log rule. — Using as the formula for a 16-foot log: 

 V= CD— 4)2. 



Scribner log rule. — Using as the formula for a 16-foot log 

 with allowance, for a %-inch saw kerf: V=0.79D 2 — 2D — 4. 



International log rule. — Using as the formula for a 16-foot, 

 log, with allowances for a %-inch saw kerf and J4 6 -inch 

 shrinkage: V= 0.07961)2- 1.375D- 1.23. 



Diameters 



D. b. h. {diameter at breast height). — Diameter, outside of 

 bark, A)A feet from the ground. 



Two-inch diameter classes. — Including diameters 1 .0 inch 

 below and 0.9 above the stated midpoint, e. g., trees 5.0 to 

 6.9 inches d. b. h. are placed in the 6-inch class; cor- 

 responding limits apply to the other diameter classes. 



VI 



