32 INSTRUCTIONS FOR MAKING FOREST SURVEYS. ETC. 



$1,000 per square foot. The surveys of the Forest 

 Service call for practical accuracy, rather than technical 

 correctness or precision. 



Figure 10 shows the changing areas in the survey of 

 a square mile in which there is a compass error of one- 

 fourth degree. When measurements close, but not at 

 right angles, the result is a diamond, and the loss in area is 

 about 0.02 of an acre, representing a value of only 5 or 

 10 cents. In a converging section the loss may be 2.80 



Perfect square. Diamond. Converging quadrangle. 



FIG. 10. Areas of a section containing a compass error of 0.25 degree. 



acres, but in either instance such a survey is considered 

 to inclose a conventional section of 640 acres, and this 

 will also be the case if there is an excess acreage to the 

 same extent. To survey a perfect square would be very 

 expensive and not justifiable in view of the trifling 

 values involved. 



TRAVERSE. 



When a survey is run along a road or stream, or fol- 

 lows the crest of a divide, the line "meanders'' and 

 consists of a number of short courses and distances. 

 The courses are read from the north end of the needle 

 and platted on the map with a protractor. Whenever 



