110 THE BOOK OF FORESTRY 



number of board feet be obtained and total measure- 

 ments are rarely taken. 



Locating the Boundaries. Such a system requires a 

 knowledge of the exact area in acres so if a map has 

 not already been made, the boundary lines must be run 

 and the area computed. These lines are generally run 

 with a surveyor's compass, since a transit requires too 

 much clearing out of the line of sight to be easily used 

 in forest surveying. 



If the boundary lines have not been run for many 

 years, their retracing is a matter of great skill and 

 one that requires much experience. The ax marks or 

 blazes on the line trees have grown over; the corner 

 trees with their markings may have been blown down or 

 burned, and it is only by exercising all the skill of a 

 trained woodsman that many old lines can be located. 

 For work of this sort, the aid of an expert should be 

 secured, as he is accustomed to detecting the signs 

 upon trees. If the lines have been run more than 

 once it may be necessary to chop into the tree and see 

 if the overgrown scar was made the correct number of 

 years ago. If the correct survey was made in 1845 

 and the lines are rerun in 1915, chopping down to the 

 original scars should expose seventy rings. In this way 

 the age of the survey is told. 



Strip Surveys. After the boundaries have been located 

 and well marked and the area has been computed, a start 

 is made at a convenient point and parallel compass lines 

 are run back and forth across the tract equal distances 

 apart and all the trees on a strip four rods wide, two 

 rods on each side of the compass line, are measured. 

 The diameter of the trees within this strip, whose width 

 is largely obtained by the eye, are measured four and 

 one-half feet from the ground with a pair of large cali- 



