MEASUREMENT OF DISTANCE 
17 
tance a e may be computed by traverse. If a e runs N and 
S, the distance a e will be the latitude of the traverse, or, 
stated in other words, it will be the sum of 
the products of the cosines of the several 
courses into their respective distances. The 
departure of such a traverse should be zero. 
Thus, if e is not visible from a , or if it is not 
convenient to take the range a e, e may be 
set when the sum of the departures figures 
up 0. This process of surveying a lake or 
river shore is called “ meandering.” It is the 
method pursued in the United States land 
surveys on considerable bodies of water. The 
same method may also be employed to get 
round a precipitous hill or some other inac¬ 
cessible object. 
An example of the computation necessary 
for solving a problem of this kind is given on 
page 33. 
8. Method by 60° Angles. (G) A precipitous bluff or 
impassable swamp may occasionally be passed most read¬ 
ily in the following manner. With 
the compass at a, lay off a 60° 
angle and run out a c, carefully 
chaining. Next, making an angle 
of 60° at c, run out c b to an equal 
distance. Then, if the work has 
been done accurately, b is in the 
line and a b = a c — b c. 
In working by any of these 
methods it is better, if possible, 
to set b in range by the compass 
from a rather than to rely for the range on any process of 
figuring or angulation. 
Fig. F 
6. Stadia Measurement 
A substitute for chaining, which has to some extent 
been employed in forest land surveying and which deserves 
