wth, 
INSTRUMENTS USEFUL TO A WOODSMAN. 105 
The hand level is often of use to lumbermen in laying out roads 
and trails and in locating dams. To use the instrument as a hand 
level it must first be set by swinging the case containing the spirit 
tube into line with the main tube. The observer then sights at an 
object through the tube, which he brings to a level by the bubble 
reflected in the mirror, and then notes whether or not the object 
is above or below the cross wire. If the object is in direct line 
with the cross wire it is on the same level with his eye; other- 
wise the object is above or below the level of his eye, as the case 
may be. 
The lumberman may also use the hand level in finding the 
height of a hill, or the height of any point on the slope of a hill, 
as is necessary in making topographical maps. To find the height 
of a hill, the observer begins at its base, and after leveling the 
instrument, sights in the desired direction, and notes the point 
ahead intersected by the cross wire; he then advances to that point 
and repeats the operation, and so moves up the hill from point to 
point until the top is reached. As between each observation he 
advances a height equal to the distance from the ground to his 
eye, the height of the hill will be the product of that distance by 
the number of observations taken. 
The instrument may also be used as a clinometer to ascertain 
the slope of a hill. To do this the observer sights the instrument 
at an object on the slope which is the same height above the 
ground as his eye and located above or below where he stands, 
according as he is sighting up or down the hill. He now uses the 
handwheel to swing the tubular case until the bubble shows it is 
level. The measuring arm, which swings with the case, is at the 
same time swept over one or the other of the two scales, and 
indicates upon it the slope of the hill in degrees. 
If the observer will provide himself with a table of natural tan- 
gents, he may use the instrument for measuring the height of 
trees. He sights the instrument at the top of a tree and turns the 
handwheel until the bubble shows that the case is level, at which 
time the measuring arm, which swings with the case, indicates » 
upon the right-hand scale in degrees the angle formed by a line 
running from the observer’s eye to the top of the tree and a hori- 
zontal line extending from his eye to the trunk of the tree. He 
then consults his table of natural tangents, which gives him the 
