when using a line. a. The straight
distance between two points is to be obtained. b. The point where the
end of the line comes each time must be marked. c. The line must be
stretched tight.

This method can be used in measuring off the distance for pacing to
obtain the average length of one's pace, as suggested in a later
paragraph under Useful Personal Measurements.

(2) Telemetry. The second method is used in determining long distances
for artillery practice and in surveying. It is called telemetry and the
use of an instrument is necessary.

(3) Triangulation. This is a long word but one a Scout can learn to know
and use. It means that the length of the distance can be computed by
means of triangles staked out on the ground, when to measure with a line
would be impossible or not satisfactory. It is not necessary to make the
sides of the triangles, only the points need to be indicated as it is
the relative position of the points which make a triangle and not the
lines. These can be marked in the country with poles, stakes or stones;
in the city Scouts could stand in position at the necessary points.

When using triangles where shall a Scout place the points?

If the width of a stream, road or field is wanted choose a place where
its sides are on about the same level and if possible fairly straight.
Then proceed as shown in the accompanying diagram A. Select a
conspicuous object on the farther bank of the stream, such as a tree,
bush or stone and call it X. Stand opposite it at the near edge of the
stream or on the bank, and place a stake A in front of you keeping X and
A in direct line, walk backward a few feet and plant a stake B in direct
line with them. Right or left face--(for a right angle is necessary at
this point). Pace a straight line for say 20 feet and plant a stake C,
one high enough to be plainly seen; continue the straight line for say
10 feet more and plant a stake D. Turn inland, (another right angle is
here necessary) and pace to the point where the object X on the far
side of the stream can be seen in direct line with the stake C. At this
point place stake E. Measure the distance from E to D. With paper and
pencil mark down the example--for such it is--in this way:

DC : CB :: DE : BX
or
as the length from D to C is to the length of C to B
so
is the length from D to E to the length from B to X
or as in th