The Measiirement of Saw Logs 85 



allowance to be made for neglecting the fractions of inches in 

 measuring the widths of the boards sawn from logs is likewise in 

 proportion to the bark surface and may most conveniently be 

 grouped with the edging waste in computations. 



Edging waste is due ( i) to the ciradar form of logs, (2) to 

 the minor crook (irregularity of surface), and (3) to major crook 

 or ' ' sweep ' ' in logs. In the case of perfectly straight smooth 

 logs the allowance for edging need provide for waste in trim- 

 ming the wane from sawn boards only. Few logs, however, are 

 either perfectly straight or free from superficial irregularities. 

 It is therefore necessary that in the computation of any practical 

 log rule due provision be made for these normally occurring 

 defects in the form of the average log. 



The allowance for edging the lumber from logs of various diam- 

 eters and degrees of crook was first determined theoretically by 

 mathematical computation aided by draughting. The amount to 

 be added to this theoretical allowance to provide for the additional 

 loss due to human and mechanical imperfections was next deter- 

 mined by sawing out very carefully measured (white pine) logs 

 having all degrees of crook. I shall not here go into the details 

 of this interesting study but content myself with a statement 

 of my results. 



1 . The discovery that the edging waste remains practically con- 

 stant regardless of the width of kerf cut by the saw has been al- 

 ready noted and fully explained. 



2. It was found that the waste due to crook (major and minor) 

 of all degrees was in direct proportion to the circumference of the 

 logs sawn ; i. e. the waste due to any particular degree of crook 

 in a 20-inch log was practically double that caused by a similar 

 amount of crook in a lo-inch log. 



3. When provision is made in the scaling score for an average 

 taper of i inch per 8 feet lineal, and when the logs show an aver- 

 age major crook oi i]4, inches per 12 feet, the necessary allow- 

 ance for edging waste as above defined was found to be . 8 foot 

 board measure per square foot of bark surface for white pine logs of 

 all dimensions. 



The effect of increasing major crook on the product of sawn 

 lumber was also studied. The results of such a study depend di- 

 rectly on the size of the smallest board which is regarded as mer- 

 chantable by the investigator, for with increasing crook there is 

 a greatly increased out-put of short lengths sawn from the heavy 



