' DISCUSSION OF LOG RULES. 33 



Log rules of this form are correct in principle, and can be adapted 

 to conditions existing at different mills, and to the character of the 

 timber in different localities. The sawdust allowance, however, should 

 not be fixed, but should depend upon the width of saw-kerf and the 

 average dimensions of the lumber. The slab allowance should also be 

 flexible, and should be determined by the timber to be sawed. Allow- 

 ances for taper, excessive taper in small logs, shrinkage, etc., can be 

 applied when making up a table based upon 



This type of log rule can be represented diagramatically by drawing 

 concentric circles of diameters D and (D a) respectively. The differ- 

 ence between the two rings will represent slab allowance. Draw a 

 sector of the small circle with angle equal to c X 360. This will 

 represent the sawdust allowance. 



The following is a comparison of log rules which may be expressed in 

 the form : 



(1 c) 

 ' 



4 X 12 

 Constantine : 



(1 0)- -L = B.M. 

 '4X 12 



Saco River: (Original values slightly erratic) 



Derby: (Original values slightly erratic) 



Square of Three-quarters: 



Partridge: (Original values slighty erratic) 



