30 INSTRUCTIONS FOR MAKING FOREST SURVEYS, ETC. 



With the thumb pressing the release, the sight is 

 taken on the object and the height is read at the same 

 time; or the thumb may be lifted, and the pendulum 

 thus being clamped, the height of the tree may be read 

 through the window. 



If the observer stands only 50 feet from the tree the 

 reading must be divided by 2. If he stands 200 feet 

 away it must be multiplied by 2, and proportionately 

 for other distances. 



The reading gives the height above the level of the 

 eye. Allowance must be made if the observer's eye is 

 above or below the stump height of the tree. 



The notebook and pencil are held in the right hand 

 while an observation is being taken, and the notebook 

 is passed to the left hand when the observation is 

 entered. The hypsometer being on the back of the 

 fingers allows free play for the thumb, palm, and ends 

 of the fingers of the left hand to hold the notebook. 

 In moving from station to station the right hand is 

 then free to assist in getting through the brush or in 

 crossing logs. 



The circular pendulum is graduated to tangents. 

 Therefore it may be used to determine the per cent of 

 grade of a road or trail. For this purpose sights may 

 be taken downhill as well as uphill. No conversion of 

 figures is necessary. If the reading is 10 the grade is 

 10 per cent. It will not hereafter be necessary to use 

 pocket levels for this class of work, since the hypsom- 

 eter-grademeter answers every purpose. 



