40 Practical Forestry 



The difference between the sums of the numbers in these two 

 columns will be equal to the height of one extremity (a) 

 of the line, above the other (d). When a number of levels 

 have to be taken in succession, it will be found a saving of 

 time to use the surveyor's level or theodolite instead of the 

 ordinary spirit-level illustrated. 



With regard to the use of the instrument as shown in 

 Fig. 1, it may be necessary to state that the height of the 

 eyesight & from the ground must be deducted from the 

 point observed. As an example : if the object-pole or 

 staff be marked in feet or inches, and the hair wire in taking 

 a sight strike the same at, say, 8 ft., then, if the eyesight 

 be 4 ft. from the ground, the difference of level between 

 the two stations (instrument and station) will be 4 ft., 

 that is, there will be 4 ft. of a fall from the spirit-level 

 station to that of the station where the staff was placed. 

 On the other hand, should the hair wire strike the object 

 pole at, say, 2 ft. from the ground, these 2 ft. must be 

 deducted from the height of the eyesight, which, as we have 

 said, was 4 ft., then the ground at the station-pole must 

 be 2 ft. higher than that at the spirit-level. 



Clearing the Ground. Coarse-growing herbage, which 

 often includes heath, gorse, and rough grasses, that would 

 interfere with planting operations, should be removed, but 

 not indiscriminately, as it may prove of inestimable value 

 under certain conditions. On exposed and high-lying 

 ground, the heath and grasses will prove of great advantage 

 to the young trees, and usually they are not too luxuriant 

 or apt to cause damage at high altitudes. Where, however, 

 the growth of such shrubs or grasses would be detrimental 

 to the young trees, by all means have them removed. The 

 best way is either to cut them over or grub out by the root, 

 and burn on the ground. During a continuance of dry 

 weather it may be possible to burn without either cutting 

 or uprooting, but, generally speaking, removal of the roots 

 is to be encouraged. 



Pitting. The advantages of pitting over any method of 

 planting cannot be questioned, and this is particularly the 

 case with ground that has hitherto been uncultivated. Com- 



