STOliRS AGlilCULTUUAL EXrElilMENT STATION. 



315 



tions Ijegiiniiiig- at C. A thread witli a weiglit is attached at M 

 and hangs tree from the zero point ot tlie top of MC. In use a 

 convenient distance, sa)' 100 ft. from the tree, is first measured off 

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

 pends tlie aeeuraey of the lieiglit esliination. At tlie 

 100 ft. mar]^ tlie top of the tree is sighted along the 

 straight edge AF which niav more cou\-enientl\' be fitted 

 with some simple foi'm of siglits. At the jioint B, where 

 the plumb line ci'osscs the line C'K the height of the tree above 

 file eye is indicated in feet. The heiglit of the eye aljove 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 t'H added or subtracted, according to whether 

 the base ot tlie tree is below or above 1lic c\'e ]e\'el. If in the 

 instrument as (igui'cd, the liase line had liceii IIKI ft. as suggested, 

 the height of the 1ree above the eye is gAeii as 4l) ft. If, however, 

 the base line bad been -jO ft. tlie height is gi\"cii as 20 ft., the 

 readin.g lieing iaki'ii at the intersection ol the Ihi-cad \\itb the line 

 running leiigtlnvise tliroiigh wbate\er niiinljci- on ^I( ' has lieen 

 used to repi'csent the liase line. Tlie t«'o sniallei' diagrams show 

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



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Kig. '2. Height Measurer in pcsition for sighting to top of tree. 



