THE CONTENTS OF LOGS AND TREES 175 



for them, otherwise the values will be too high. What is 

 wanted in scaling logs is the number of board feet that can 

 actually be sawed out of the logs. No rule can be given for 

 deducting for defect in logs. It is a matter of judgment. 

 If it is believed only half the log will cut sound wood, only 

 half the scale should be recorded. Much can be learned as 

 to allowing for defects by watching logs sawed at the mill, 

 and watching the number of board feet thrown out because 

 of a certain sized defect. Crook is often allowed for by 

 reducing the diameter of the log by enough to square up the 

 log. 



Rule of Thumb for Finding the Contents of Logs in Board 

 Feet. — The following rule of thumb is a very simple method 

 of determining without the aid of a log rule the contents of 

 logs in board feet. For logs that are i6 feet in length, sub- 

 tract 4 inches from the diameter of the small end inside the 

 bark and square the remainder. It gives the contents in board 

 feet of logs according to the Doyle Rule. For example, if a 

 i6-foot log is 14 inches in diameter the rule will work as fol- 

 lows : Four inches subtracted from 14 inches leaves 10 inches, 

 and 10 squared gives 100 the number of board feet in the log. 

 If a log is 12 feet long, or any length other than 16 feet, apply 

 the rule as though the log were 16 feet long, then take the part 

 of the scale that the length of the log is of 16. If the log 

 is 12 feet long three-quarters of the scale of a 16-foot log 

 of that diameter is used. If a log is 8 feet long one-half the 

 scale is taken. 



Finding the Volume of a Tree. — The Cubic Contents. — 

 The usual form of a tree is a paraboloid or a cone with slightly 

 bulging sides. The only way to find the actual solid contents 

 of an entire tree would be by displacement of water, cutting 

 the tree into parts and placing them in a tub of water and 

 measuring the amount of water in cubic feet displaced or 

 that runs out. It would be almost impossible to measure 

 the limbs and twigs accurately in any other way. Such a 



