SCALING 



93 



fallen trees and for laying off log lengths. Instruments for measuring 

 the volume of saw logs or of sawn lumber and timber are known as 

 scale sticks. Instruments for determining the age and growth of trees 

 by taking a sample core of wood in a radial direction to the center of 

 the tree are known as increment borers. 



4. LOG RULES 



Log rules are tables showing the contents in board feet of logs of 

 different top diameters and lengths. The most common log rules are 

 the Doyle, Scribner, and the International rules. The Spaulding rule 

 is widely used on the Pacific Coast and is especially adapted to large- 

 size timber. 



Some rules have official status. For example, the Doyle rule is 

 the official log rule for Louisiana, Florida, and Arkansas. The Scrib- 

 ner rule is the official rule in 

 Minnesota, Idaho, Wisconsin, 

 and West Virginia. It is also 

 the official rule used in timber 

 sales and for other purposes by 

 the U. S. Forest Service. 



Log rules are computed on 

 the basis of a formula or by dia- 

 gram. Excellent rules are based 

 upon experience, that is, by tak- 

 ing actual tally of the output of 

 lumber from the different size 

 logs. 



5. SCALING 



Scaling consists of the meas- 

 urement of logs by a given log 

 rule or log scale. It is generally 

 done by one man using a scale 

 stick to measure the width of 

 the small end of the log inside FIG. 48. Scaling a deck of logs at head 

 the bark and tallying the log of chllte shown in immediate foreground. 



contents in board feet as de- Scaling 1. th , e ] gs decke< ? ^ this fash - 

 , , , .. ion is difficult because of the irregular 



termmed by the reading on the locat i on of the ends of the logs. North- 

 log scale and the length of the ern Rocky Mountains, 

 log. If logs were truly cylindri- 

 cal, symmetrical, and straight, and contained no defects such as rot 

 and decayed knots, scaling would be a very simple operation. Scaling 

 is generally done on a log deck or landing in the woods and is used 



