USE OF COMPASS 
at the end of the needle. As the course moves to the east the needle 
appears to have moved to the west, and vice versa; for this reason 
E. and W. are often reversed in position so as to make correct 
reading easier. 
Methods of Use 
In use the compass 
should be held in an 
approximately horizontal 
position and as steadily 
as possible. It is easier 
to do this if the arms from 
shoulder to elbow are 
pressed against the body 
and any rotation of the 
compass done by twisting 
the body rather than by a 
motion of the wrists. 
Some compasses have 
two small level vials at- 
tached at right angles so 
as to show when the in- 
strument is level; in others 
the observer must judge 
by the position or motion 
of the needle or of the 
sight vanes whether or 
not the instrument is near- 
ly level. Fig. 15. Usine THe Pocket TRANSIT 
The compass needle 
is easily affected by iron or steel, and care should be taken not to 
use it near any such metal. Even for approximate hand work it 
should not be used within 8 or 10 feet of a wire fence or telephone 
line or 20 or 25 feet of a railroad, while for careful instrument work 
37 
