42 



then a strip is run back parallel to the first, as indicated on 

 the diagram. If the long chain, 66-foot, is used, 10 chains 

 make an acre; if the short chain, 33-foot, is used, 20 

 chains make an acre. 



170. There are several log rules in use. Most of them 

 were made with Northern conditions in view. The follow- 

 ing rule has been constructed for the purpose of getting a 

 rule adapted to the conditions found in the average small 

 mill in Georgia. It is based on the following suppositions; 

 that the saw-kerf is a quarter of an inch; that the boards 

 are an inch thick, the smallest 3 inches wide and the largest 

 12; and that the logs are normally sound and straight. A 

 special allowance must be made for hollow and very crooked 

 logs. The height to which the logs will run is estimated. 

 A ten-foot pole set against the tree is a great help in estima- 

 ting heights; for it gives a point for comparison. After a 

 little practice the pole may be set aside. When the distance 

 from the ground to the point where the tree ceases to be 

 usable has been estimated and the height of the stump de- 

 ducted, the trunk is divided into logs. If, for instance, the 

 usable part of the tree is 33 feet long, it will make two 

 16-foot logs. The next step is to estimate the diameters of 

 the top ends of the logs. A steel square is helpful in esti- 

 mating diameters. Hold it in one hand at breast height 

 with the tongue and blade against the tree; then a lath or 

 straight stick held in the other hand laid against the tree 

 parallel to the tongue will indicate the diameter on the blade. 

 With the diameter at breastheight known, the diameter at 

 the tops of the logs can be estimated by comparison. In a 

 short time the eye becomes accustomed to estimating diam- 

 eters without the use of the square. The rule is for diame- 



