94 
HINTS TO TRAVELLERS. 
In filling in a survey, the observer can fix his position, 0, by observing 
two fixed points, A and B, and plotting from those points the opposite 
bearings to those observed; their intersection fixes the point required. 
The nearer the two bearings meet at a right angle the more correct will 
the point be determined, and, if a third fixed point is visible, a bearing to 
it will act as a check on the other. 
A third and accurate method of fixing the position is by the angles 
subtended between three known objects. The instrument called the 
station-pointer is generally used for this purpose; but the position may 
also be found with a pair of compasses and protractor, or, more simply. 
as follows, by means of a protractor and a sheet of tracing paper. Draw 
a line through the centre of the paper; place the protractor on it near to 
the bottom of the sheet; lay off the right-hand angle to the right, and the 
left-hand angle to the left of the centre-line; rule pencil-lines, radiating 
from the point over which the centre of the protractor has been placed, 
to the points that have been laid off; then place the paper on the plan or 
map, and move it about until the three lines coincide with the objects 
taken; prick through the point that lay beneath the centre of the 
protractor, and the observer’s position is transferred to the plan. When 
possible, the centre object should be the nearest. 
