Brunton ECLIPSE 8099, Instruction Manual

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4. Above the horizon (level, 0°), sight top of
object through sight hole (figure 44).
5. Read bearing from black scale ( 38° , this
example).
6. Above the horizon (level, 0°), sight base of
object through sight hole (figure 44).
7. Read bearing from black scale ( 10° , this
example).
8. Calculate height of the object.
· Height = (TanA – TanB) x Distance
·
Height = (Tan38° – Tan10°) x 75 feet
· Height = 45 feet
12.3 Percent Grade
After measuring the angle of inclination (20°),
and finding the tangent of the angle (20°), move
the decimal two places to the right.
· Example: Tan20° = 0.364 = 36.4% Grade
Remember to readjust for magnetic declination before sighting a bearing.
13 – Additional Information
Before heading into the field, practice using the Eclipse  8099 and a map in a familiar area. Also,
carefully re-read the instruction manual to gain a full understanding of Eclipse 8099 applications.
Become an expert with map and compass and you should never get lost. Also, carry a complete
survival kit and educate yourself on survival techniques.
14 – Eclipse

8099 Specifications
Magnetism: NdFeB needle disk
Accuracy: Bearing -- ± 1° accurate reading (0.5° readable)
Clinometer -- ± 1° accurate reading (0.5° readable)
Dimensions: 4.2 x 2.8 x 1 in. (10.7 x 7.1 x 2.5cm)*
Weight: 4.1 oz (116g)**
* Includes Eclipse 8099 compass and rubber shoe
** Includes Eclipse 8099 compass, rubber shoe, reference cards and lanyard
12 – Height Measurement
We can now apply clinometer measurements to height measurement and percent grade. In order
to calculate the height of an object a distance must be known to the object, and the angle of incli-
nation must be determined. The following example uses the 1° graduated dial clinometer.
12.1 Level Ground Height Measurement
1. Measure distance to object (
50 feet , this example)
2. Adjust blue orienting circle to clinometer
index mark.
3. Position the compass at eye-level with
mirror extending outward to the left.
· See section 11.3.a, Up Angle, for help.
4. Above the horizon (level, 0°), sight top of
object through sight hole (figure 43).
5. Read bearing from black scale ( 36° , this
example).
6. Position the compass at eye-level with
mirror extending outward to the right.
· See section 11.3.b, Down Angle, for help.
7. Below the horizon (level 0°), sight base of
object through sight hole (figure 43).
8. Read bearing from green scale ( 10° , this
example).
9. Calculate height of object using the equation.
· Height = (TanA + TanB) x Distance
·
Height = (Tan36° + Tan10°) x 50 feet
· Height = 45 feet
Note: Do not calculate tangent of an angle by adding tangents of two smaller angles.
Example: Tan(60°) is not equal to Tan(30°) + Tan(30°). You must find Tan(60°) from another
table, use a calculator, or step back from object until the angle of inclination is less than or
equal to 45°, to use tangent tables provided on reference card 8.
12.2 Sloping Ground Height Measurement
1. Measure distance to object (75 feet, this example)
2. Adjust
blue orienting circle to clinometer index mark.
3. Position the compass at eye-level with mirror extending outward to the left.
· See section 11.3.a, Up Angle, for help.
22 23
Figure 44
Figure 43