342 Forestry Quarterly 



method is no exception to the rule. The Abney hand level must 

 be kept in perfect adjustment. The man who fails to test the 

 instrument every morning has no place on a forest-survey crew. 

 The mapper must be exceedingly careful to see that he is not 

 sighting uniformly too high or too low. 



Abrupt changes of slope frequently give trouble. Perhaps 

 the mapper will not be able to see the man at the other end of 

 the tape at all when he reaches the new point, due to a sharp 

 ridge, or to a sudden drop or rise in the ground. He must then 

 "break chain," as it were, and figure the shorter distance. The 

 tape length may carry the compassman across a gully or draw, 

 with an abrupt descent and rise. Shall he "break chain?" Or 

 shall he proceed to the end of the chain, pull it taut, then get the 

 proper correction? 



The members of a crew must always work together so as to lose 

 the least amount of time. Oftentimes the compassman is through 

 mapping at a particular point before the estimator reaches him. 

 Shall he wait, then go ahead his tape length, and again wait for 

 the estimator to come up? Or shall he mark the point promi- 

 nently and go ahead, being careful not to pull the end of the 

 tape past the mark before the estimator reaches it? Where 

 there is very little underbrush, a deep mark made with the heel 

 can usually be picked up easily. Where there is much brush, the 

 estimator may have trouble finding the mark, if the compassman 

 starts ahead too soon. It will often be found helpful in brush 

 country for the compassman to carry some waste paper with him, 

 and impale a small piece on the brush, over the mark on the 

 ground. In brush that breaks easily, two or three pieces of 

 brush broken will answer equally well. 



The most serious drawback to the use of the hand level and the 

 tape in mapping on forest surveys is brush. In heavy, stiff brush, 

 the tape may catch and hold tightly until released by one or the 

 other of the crew. Under such conditions it must be pulled with 

 great caution to prevent its breaking. It must not be overlooked, 

 however, that the estimator can follow his compassman's line 

 easily in brush when he has the tape as a guide. The great 

 drawback lies in the inability of the compassman to see in sighting 

 the hand level. This difficulty may at first appear insurmount- 

 able, but the fact of the matter is that the sound of the esti- 

 mator's voice may be substituted for actually seeing him. The 



