STORKS AGRICULTURAL EXPERIMENT STATION. 315 



tions beginning at C. A thread with a weight is attached at M 

 and 'hangs free from the zero point of the top of MC. In use a 

 convenient distance, say 100 ft. from the tree, is first measured off 

 as a base line, and upon this measurement largely de- 

 pends the accuracy of the height estimation. At the 

 100 ft. mark the top of the tree is sighted along the 

 straight edge AF which may more conveniently be fitted 

 with some simple form of sights. At the point B, where 

 the plumb line crosses the line CK the height of the 'tree above 

 the eye is indicated in feet. The height of the eye above the 

 ground is added to this reading if the measurement is on the 

 level, or a second sight may be made to the base of the tree and 

 the reading noted on CH added or subtracted, according to whether 

 the base of the tree is below or above the eye level. If in the 

 instrument as figured, the base line had been 100 ft. as suggested, 

 the height of the tree above the eye is given as 40 ft. If, however, 

 the base line had been 50 ft. the height is given as 20 ft., the 

 reading being taken at the intersection of the thread with the line 

 running lengthwise through whatever number on MC has been 

 used to represent the base line. The two smaller diagrams show 

 the instrument in position for sighting to top and base of tree 



Fig. 2. Height Measurer in position for sighting to top of tree. 



