Clinometer

work report

1. INTRODUCTION

An inclinometer or clinometer is an instrument for measuring angles
of slope (or tilt), elevation or depression of an object with respect to gravity. It
is also known as a tilt meter, tilt indicator, slope alert, slope gauge, gradient
meter, gradiometer, level gauge, level meter, declinometer, and pitch & roll
indicator. Clinometers measure both inclines (positive slopes, as seen by an
observer looking upwards) and declines (negative slopes, as seen by an
observer looking downward) using units of measure: degrees, are
inclinometers that were used for navigation and locating astronomical objects
from ancient times to the Renaissance.

2. HOW TO USE
A forester using a clinometer makes use of basic trigonometry. First the
observer measures a straight-line distance D from some observation
point O to the object. Then, using the clinometer, the observer measures the
angle a between O and the top of the object. Then the observer does the same
for the angle b between O and the bottom of the object. Multiplying D by
the tangent of a gives the height of the object above the observer, and by the
tangent of b the depth of the object below the observer. Adding the two of
course gives the total height (H) of the object.
The forester stands at a fixed distance from the base of the tree. The most
common distances in the United States are 50 feet (15.24 m) and 66 feet
(20.12 m).

To obtain accurate readings it is best to use taped measured
distance instead of paced distances. For the most accurate readings it is best
to use a distance that is not less than the height of the tree being measured,

.
that is, that the clinometer will measure an angle less than 45° (100%).
The observer sights to the top of tree, if total height is the desired
measurement. If the desired measurement is merchantable height – that is,
the height producing timber that can be sold – the observer sights to a point
on the tree above which no more merchantable timber is found. Note that the
observer should use slopes expressed as a percent. The observer then
measures to the bottom of the tree, again using percents. The observer than
takes the slope to the top of the tree, and subtracts the slope of the bottom of
the tree from it. Note that when the ground slopes downwards, the observer
will record a negative slope to the base of the tree. When this is subtracted

3. from the slope to the top of the tree, it is actually being added. These numbers
are then divided by 100, and multiplied by the distance from the tree.
There is still some error in this number, because the distance is measured
along the ground, and is not the actual horizontal distance. By standing at the
base of the tree, the observer should mark his/her eye level. They then stand
back, and find the slope expressed as a degree to the mark. This is the slope of
the ground. By taking the cosine of that number, and multiplying it with the
previous number, the observer will calculate the height of the tree.
The observer must always measure a leaning tree so that the tree is leaning to
the left or right. Measurements should never be taken with the tree leaning
toward or away from the observer because this will affect
their accuracy because of foreshortening.
The clinometer is also commonly used by foresters to obtain the percent
slope of terrain. This measurement is based on the same trigonometric
principles described above. Slope measurements, however, require that both
observer and target be a constant height above the ground; thus a range pole
or height of measurement (HI) stick is often used in slope measurements.

4. APPLICATION
Inclinometers are used for:
 Showing a deviation from the true vertical or horizontal.
 Surveying, to measure an angle of inclination or elevation.
 Alerting an equipment operator that it may tip over.
 Measuring angles of elevation, slope, or incline,
 Measuring slight differences in slopes, particularly for geophysics. Such
inclinometers are, for instance, used for monitoring volcanoes, or for
measuring the depth and rate of landslide movement.
 Measuring movements in walls or the ground in civil engineering projects.
 Some automotive safety systems.
 Indicating pitch and roll of vehicles, nautical craft, and aircraft. See turn
coordinator and slip indicator.
 Monitoring the boom angle of cranes and material handlers.
 Measuring the "look angle" of a satellite antenna towards a satellite.
 Adjusting a solar panel to the optimal angle to maximize its output.
 Measuring the list of a ship in still water and the roll in rough water.
 Measuring Range of Motion in the joints of the body
 Measuring the inclination angle of the pelvis. Numerous neck and back
measurements require the simultaneous use of 2 inclinometers. .
 Measuring the angles of elevation to, and ultimately computing the
altitudes of, many things otherwise inaccessible for direct measurement.
 Setting firing angle of a cannon or gun (determines projectile range)
 Electronic games