26 



BULLETIN" 8 6 3, U. S. DEPARTMENT OP AGRICULTURE 



probably the most common rule in use is the Doyle, although for 

 small logs under 16 to 20 inches it is very inaccurate, because from 

 one-third to one-half more lumber is usually sawed out than is indi- 

 cated by the rule. The international log rule (for 14-inch saw kerf) 

 gives more nearly what small mills cut from logs. (See page 43.) 



Illustrative material. — Procure any 

 saw timber is measured and estimated. 



Language : 

 of a 



good pictures showing how 

 Observe and study the con- 

 tent of tables for scaling 

 logs. 



Correlations 

 Write an account 

 method of scaling logs. 



Arithmetic : Scale and es- 

 timate the number of feet 

 in a given saw log. 



How bolts and billets are 

 measured. "What makes a 

 standard cord of wood? 



Allowances made for de- 

 fects in saw logs, bolts, 

 or blocks, and in other 

 material. 



Estimating standing 

 trees : Finding approxi- 

 mately the contents of 

 standing trees in cords or 

 board feet of lumber by 

 measuring the diameter at 

 breast height (4% feet 

 above the groimd), esti- 

 mating or measuring the 

 number of 16-foot log cuts 

 in the tree, and by the in- 

 formation given in Farm- 

 ers' Bulletin 1210. (Fig. 

 16.) Find the merchant- 

 able contents of the tree 

 expressed in board feet. 

 Estimating whole woods : Applying the same method to all the 

 trees on a measured one-tenth or one-quarter acre, and thereby esti- 

 mating the contents per acre. Recording the measurements by dif- 

 ferent species on a simple blank form ruled in squares in two 

 directions. 



Practical exercises. — This lesson should be essentially one of prac- 

 tice. The class should measure logs according to the Doyle and inter- 

 national rule (page 34). standing trees by the use of volume tables 

 for trees and tree-scale stick (fig. 16), and cordwood by dimensions of 

 the piles. A good exercise for the more advanced students is to make 

 estimates on logs and standing trees and then by applying the Doyle 

 and the international rules or the volume table test the accuracy of 

 the estimates. The practical value of this lesson is in acquainting 

 the pupils with comparatively easy ways by which they can measure 



Figure 16. — Measuring and estimating the saw- 

 timber in a stand of shortleaf pine 



