118 
HINTS TO TRAVELLERS. 
the angle to the next forward station, C, the angles being read from the 
opposite vernier to that previously used. When the forward angles are 
taken to the right of the zero line, passing through a station , they will be 
less than 180°, when to the left of the zero line they will be more than 
180°. By noticing this it is easy to tell which vernier should be read. 
The traverse is carried out in this manner to all the forward stations, 
reading the angles alternately on the two verniers. Should the traverse 
be carried to a closing point, as from D to Y, the vernier of the vernier 
plate should be at zero when the theodolite is set up at Y, and the point 
A bisected with the cross threads of the diaphragm. The approximate 
accuracy of the work may also be tested at each forward station, by 
setting the vernier to 360°, when one end of the compass needle should 
point to the bearing noted of the zero line. In plotting the work it 
must be borne in mind that all angles are plotted with reference to the 
zero line. 
The second method differs from that previously described, in which 
all angles are referred to a common zero line, as it consists of making the 
station last left zero, and taking rounds of angles at each station to the 
points it is desired to fix. The compass bearing of the second station 
from the first station must be recorded. 
B 
