62 



NOTES ON FORESTRY. 



venient of which is that figured in the margin. A 

 is a stock about 5 feet long, pointed 

 for insertion in the ground, and 

 mounted at top with a brass ferule, 

 one side of which has a female 

 screw. B is aboard about 6 in. square, 

 divided perpendicularly and hori- 

 zontally into tenths, which ordinarily 

 represent each 10 feet, and is fixed to 

 the upright by a screw in the centre 

 at the back. At the upper edge of 

 the board are two brass uprights, 

 one of which, D, is perforated with 

 a pinhole ; the other, E, is a frame 

 across which a fine wire is stretched 

 on the same parallel as the pinhole. 

 At the right-hand corner, at top, F, 

 is inserted a strong thread of silk, 

 to which a small weight, C, is sus- 

 pended. 



Provided with this instrument, 

 the operator selects a convenient 

 spot from which there is a clear 

 view of the top of the tree; this 

 spot should be nearly on the same 

 level as the tree stands, and about 

 as far from it as the tree is high. 

 Inserting the stock firmly and per- 



