A COMPARISON OF THE DOYLE AND SCRIBNER 



RULES WITH ACTUAL MILL CUT FOR SECOND 



GROWTH WHITE PINE IN PENNSYLVANIA. 



By N. R. ]\TcNAur,HTON. 



The fact has long been recognized that the old log rules, de- 

 signed for use with virgin timber of large size, give results which 

 are far from accurate when applied to our present stands of 

 second growth timber. The reasons for this inaccuracy may 

 be roughly outlined as follows : 



(i) As' stated above, the rules were designed for use with 

 old trees, hence a greater proportionate reduction was neces- 

 sarily made for defects, such as shakes, rot, etc. 



(2) Logging and milling operations were conducted on a 

 less intensive scale than at present. Measurements* were less 

 accurate, and the waste in the woods and at the mill was greater 

 than it is to-day. 



(3) Most of the rules are based on incorrect and inflexible 

 formulas or diagrams. By the statement that the formulas and 

 diagrams are inflexible it is meant that they cannot be modified 

 easily so as to be made applicable to local metliods of manufac- 

 ture and local species and grades of logs. 



It has been the custom of the Pennsylvania Department of 

 Forestry to base its sales on actual mill cut, or on scale by the 

 Doyle Rule plus twenty-five per cent. This latter is a tacit 

 recognition of the painful inaccuracy of this rule in present day 

 use, and the same words apply in greater or less degree to al- 

 most every other log rule commonly employed. 



To determine just how far the old rules fall short of actual 

 mill cut under average conditions, the Pennsylvania Department 

 of Forestry authorized the collection of data, a part of which 

 the following tabulations summarize. This data was collected 

 in Cameron county, Pennsylvania, during 1912. The logs came 

 from a stand of second growth white pine about seventy-five 

 per cent, pure, which was killed by fire in the spring of 191 1, 

 and was cut the following winter. Only normal, sound, white 

 pine logs were taken; that is, an attempt was made to secure 



