 |
The
Living History Engineer's Triangulation |
|
The
Living History Engineer's Triangulation |
In
short, there are two methods to use in calculating distances using
triangulation. For the more accurate and scientific, you will need a table of
logarithmic functions. These predate the Civil War by many years and their use
in triangulation is attested at the Lewis & Clark page at http://www.surveyhistory.org/distance_across_a_river.htm.
The actual formula can be seen (along with diagram) at http://pirate.shu.edu/~ashworha/astro/labex1_2.html,
from which it would appear that you need only one angle and one distance (the
baseline).
A
simpler way to calculate the distance is to use similar triangles. By this I
mean that you would measure out your baseline such that the far end of it (point
"B") was at a 90 degree angle to the point to which you want to
measure (point "C"). Then measure the angle from the near end of the
baseline (point "A") to point "C". Using the length of the
baseline and the two angle measurements (90 degrees and "whatever"),
draw a smaller identical triangle on a piece of paper, such that you know that
the actual length of the baseline "AB" (say it's 100') equates to say
1' on the paper. Using the ratio of 1:100, draw the line from point
"A" to point "C" (your target), and then simply measure it
and multiply by 100 (in this case). This is the simplest method, although it
takes a bit of explaining. Your men will at least look very knowledgeable
running around taking all these measurements! I suspect that this latter means
was what was more usually employed.