FORKST MKXSURATIOX. 



191 



the distance is more than sixty the slide must be taken 

 out and reversed so that the upper index mark on the 

 slide coincides with the required reading on the left-hand 

 vertical scale. 



FIG. 64. Faustman's mirror hypsometer. A BCD, frame of 

 instrument; E, mirror in which scab is reflected'; a, eyepiece; 

 b, cross-wire on which object is sighted; ge, slide and vertical 

 scale for distance of observer from tree; /, spring to hold slide 

 in place; h, marginal scale which gives height of tree. 



This instrument may also be used in taking levels and 

 grades, and may be mounted on a Jacob's-staff or tripod, 

 but is more often used in the hand. Another instrument, 

 called "Baummesser" by the Germans, mounted on a 

 tripod, is used to take heights, and by means of a stadia 

 attachment, the diameter at any point on the trunk of 

 the tree may also be measured. After some practice with 



