DISCUSSION OF LOG RULES. 37 



the value of c in the rule used and the width of the saw-kerf. The 

 effect of the constant & becomes small for intermediate sized logs, and 

 is practically negligible for large ones. Large logs will run higher in, 

 per cent of mill overrun than the intermediate, since the slab allowance 

 in this type of log rule increases directly as the volume of the log plus 

 a constant. The principle is incorrect. 



r 7t D Z i 



(1 c) b \ L = B.M. can be represented diagramatically 



L ** X 1^ J 



by drawing two concentric circles, the larger one with diameter D and 

 the smaller one with diameter sufficient to allow for & board feet ; then 

 drawing a sector forming an angle of c X 360 at the center. The 

 area of the sector and the small circle will represent the waste allowance 

 for slabs, sawdust, etc., while the remaining area will be the lumber 

 product. 



