132 THE WOODSMAN 'S HANDBOOK. 
SPECIAL INSTRUMENTS USEFUL TO A WOODSMAN. 
It is unnecessary to describe the instruments which are familiar 
to every woodsman. It is believed, however, that those described 
in the following pages are not generally known, at least in the 
form recommended. They will prove useful in many cases to 
cruisers and other woodsmen. Further information regarding 
the instruments will be furnished upon application to the Bureau 
of Forestry, Washington, D. C. They may be procured through 
any first-class dealer in field instruments. 
STAFF COMPASS. 
This instrument (shown in fig. 5) is used for running Ines 1n the 
woods. It consists of a compass set into a shallow, circular metal 
box, having two sights hinged to its edge. A removable support, 
screwed into the bottom of the box, terminates in a socket, adapt- 
ing the instrument to be mounted upon a staff or upon a tripod. 
The support also comprises a ball-and-socket joint, by which the 
compass is leveled with the aid of spirit tubes located in its bed, a 
swivel, which permits the compass to be turned in sighting it, and 
a set screw for securing it against turning after sighting. When 
not in use the sights are folded down and the support unscrewed 
from the box. When taken apart the entire instrument is in 
compact form for transportation. It is made in different sizes, 
with needles from 23 to 4 inches long. The price varies from 
$10.50 to $13; without spirit tubes, from $8 to $11.50. 
MIRROR RIGHT=ANGLE FINDER. 
This handy instrument (shown in fig. 6) is used for finding right 
angles in laying out rectangular valuation surveys. It consists of 
an open triangular metal box containing two small mirrors 
mounted in frames secured to the sides of the box and set at an 
angle of 45° to each other. Rectangular sight openings are formed 
above the mirrors in the sides of the box. The device is provided 
with a handle, preferably made removable for convenience. The 
observer looks directly into the box through its open side and sights 
the instrument through one or the other of its two sight openings 
at some given object. At the same time an object at a right angle 

