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SKU 42433 For technical questions please call 1-800-444-3353. Page 4
5. Pendulous Arm - To read the vertical angle of an object of elevation or declination.
6. Magnetic Declination Scale - Works in conjunction with the Pendulous Arm for reading angles of
elevation and declination.
7. Compass Needle - To be used with the Graduated Dial for basic bearings. The Red Mark points
toward magnetic north.
8. Peep Sight - With the Lid fully open, you can use the Peep Sight in conjunction with the Mirror to
look directly at an object while taking a reading. Warning: Do not look at the Sun.
9. Sine Chart - Standard geometrical reference numbered 1 to 45 degrees of angle and the figure
opposite each degree is the linear measurement from the baseline at 1 inch from the vertex
of the angle. For example: Envision 2 lines meeting to form a 45 degree angle. The point
they meet is the vertex. Add 1 inch from this point; the measurement from one line to the
other is .707 inches-see Figure 1.
Opening up the Compass
The Compass opens up into two sections. The lower section contains the Magnetic Needle, the
Graduated Circle, and a Sight. The upper section contains the Mirror, a Sighting Line and a Sight.
Note: The Compass produces best results when it is used on a firm, level surface.
Preparing the Compass for Use
The Compass contains a Circular Bubble Level. Check the Circular Bubble Level to make certain
that the Compass is perfectly horizontal. Make certain that the Needle is free to rotate. Extend the
Front Sight making certain that the slotted part is horizontal and that the sight is vertical.
Sighting with the Compass
Take a sighting of the object you wish to measure. A sighting can be taken either by the mirror or
using the Sight. Once the object is sighted, press down the needle clamp so that the Needle is held
in a fixed position. Note the position before unclamping the Needle.
Figure 1-Sine Chart