172 FIRST BOOK OF FORESTRY 



Since estimating is alwa3's guesswork and liable to 

 much error, it is far better to make definite measurements 

 wherever we can. This is always possible in the case of 

 the diameter, and usually of the height. In doing this 

 two men go ahead with calipers (see Fig. 62) to measure 

 the diameter and also estimate the number of logs, and 

 one man walks behind them and keeps tally. The meas- 

 uring is done breast high, and each tree is marked with a 

 gauge or chalk to show that it lias been measured. 



During the work each man calls out, as, for instance, 

 " White oak, twenty-four, two," meaning that this tree of 

 white oak is twenty-four inches in diameter and will cut 

 two logs. The heights are measured as shown in the 

 figure, with a homemade triangle or else with a special 

 device, the Faustman '' Heightmeasure." 



In measuring or '• scaling " a log, it is customary, in 

 our country, not to measure its real volume, but to state 

 how many feet B.M. of lumber might ])e cut from this log. 

 Since the saw wastes a great deal of wood, cutting it into 

 dust, and since the slabs also are largely waste, only 

 fifty to seventy per cent of the total volume of the log 

 can be obtained as boards. 



A stick on which are marked the numl^er of feet B.M. 

 for each diameter and the ordinary lengths is called a 

 scale 7'ule. Of these rules the Doyle rule is by far the 

 most common and is quite a fair rule, except for logs 

 smaller than sixteen inches diameter. If a rule is not at 



