No nails or rope in this raft. 



The instruments used in wood surveying are usually the 

 magnetic compass and the Gunter's chain. Transit lines are 

 sometimes run, and the solar compass is sometimes employed, 

 but the element of cost must be considered, and the ordinary 

 compass is recommended as being accurate enough for all 

 practical purposes. An error of one rod to a mile, 1:320, is 

 considered allowable in forest surveys. The compass is the 

 only instrument with which lines can be run in the woods at a 

 reasonable rate. 



The usual method of marking lines is by well defined blazes 

 on the trees which the line intersects, and of quarter-spot blazes 

 on trees standing near the line. Posts set at the corners are 

 surrounded with stones, when practicable, and witnessed by 

 trees being blazed down about them. 



The posts are properly marked for the corner with the timber 

 scribe or marking iron, and both posts and witness trees bear 

 the date and the surveyor's mark. Where lines cross important 

 roads and waters, the usual method is to plainly indicate them 

 by witnessings or posts so that they may readily be picked up. 



A stadia attachment to the compass is a convenient chain 

 supplement, avoiding the necessity of triangulation of inac- 

 cessible distances, such as water or gorges. 



The cost of well made compass lines in ordinary country 

 varies between $12 and $25 per mile. Such lines need not be 

 renewed for a period of twenty to twenty-five years. 



Methods 

 used in 

 surveying 



