Abney Level and the Chain 339 



For intensive work the method of using the Abney hand level 

 with pacing of the distance lays itself open to the criticism that 

 the resulting map cannot be more nearly accurate than is the 

 pacing. Therefore, under conditions where it is extremely difficult 

 to pace, owing to steepness of slope, presence of brush or wind- 

 fall, or other disturbing factors, the horizontal distance must be 

 obtained in some other way than by pacing. This has led to the 

 trial, along with the Abney hand level, of the tape or the chain. 



The tape will generally be found more acceptable than the 

 chain. The use of either renders necessary a table giving the 

 correction for the slope, which figure must be added each time to 

 the distance on the slope to give the desired horizontal distance. 



The following table shows the distance that must be added on 

 slopes of different per cents, to get the desired horizontal dis- 

 tance. The corrections for the intervening per cents can be got 

 by interpolation. 



Table of Slope Corrections 



