Computer Print-Out Lessons
DO NOT LOOK AT A BRIGHT SUN. IT WILL BLIND YOU!
You need a compass, clinometer and computer sun position program for these lessons.
Read only the compass instructions about taking readings of (azimuths/directions/
bearings) in degrees, and measuring altitudes (height) above the horizon in
degrees with the clinometer. Do not worry about compass declination adjustments
yet. We will get to that later. If you bought a Suunto Clinometer or Tandum
compass/clinometer ignore calculating the height of objects (right scale), only
use the left altitude/height above the horizon in degrees of objects such as
the sun. Ignore route finding by compass for now.
LESSON: Magnetic Compass Sun Locating (See Measuring Direction of Sun)
Print out a "magnetic north" sun position computer print-out for today. Go outside
and find magnetic north with your compass. Find magnetic east (90 degrees),
south (180 degrees) and west (270 degrees). Look on your print-out for the azimuth/direction
of sunrise and sunset and find where the sun rose and will set with your compass.
Look at the print-out for where the sun will be or was at 9:00 am. Find that
magnetic direction in degrees with your compass and notice a landmark in that
direction. Now try this for different times of the day. If there seems to be
a consistent error between your compass and the print out, you may have a strong
local compass error. If so change your position and see if things improve.
LESSON: Measuring the Elevation of the Sun or Objects.
DO NOT LOOK AT A BRIGHT SUN.
Look at your computer print-out for the altitude of the sun at 9:00 AM. With
your clinometer find that altitude in the same 9:00 AM compass direction, (using
the left scale on the Suunto Tandem). This is where the sun was or will be today
at 9:00 am. Practice this for different times of the day.
DO NOT LOOK DIRECTLY AT A BRIGHT SUN! Without looking at the sun, point your
clinometer at the sun and watch where the sun's shadow and/or reflection falls
on your finger. For an obscured sun or other object look through the clinometer
and line up the object with the horizontal line in the clinometer. Master this
when the sun is low or behind some clouds and not dangerous to look at.
If you bought a sighting compass with a build-in clinometer, read the instructions
with the compass for an obscured sun or other object. For a bright sun open
the compass lid to full length with the mirror on your right. Point the compass
at the sun and watch the shadow on your finger and read the clinometer dial.
If the dial reads "0" when flat with the horizon you are set up correctly. Ignore
the magnetic compass needle.
If you made your own clinometer from "Home Made Clinometer" read the instructions
from there. An Angle Finder from a hardware store and a small mirror to read
the dial will work too.
For other clinometers; Abney level, Alt-Track, Clinometer. Practice with low
sun before you try with a bright sun.
LESSON: Finding the Time with a Clinometer
Measure the altitude of the sun with your clinometer and see if it agrees with
your computer print-out. If it agrees with your watch you have a computer age
LESSON: Finding the Time with a Compass. Measure the azimuth of the sun. Check
the computer print-out. If it agrees with your watch you are doing everything
right.. Practice these methods until you can predict the time within 10 minutes.
LESSON: Magnetic and True Directions
Most new streets are laid out true north, south, east and west. Unless you live
in a narrow line between Florida and Wisconsin, magnetic north and true north
are not the same. Print out both a True and a Magnetic North print-out for the
day and compare them. Compare them for the declination difference for your area.
You will find this handy when we get to map reading.
© Copyright 1999-2004 Ron Dexter. All Rights Reserved.