98 
HINTS TO TRAVELLERS. 
from a towards b } and take the distance from A to B with the compasses 
from the scale on which it has been decided to construct the map; set it off 
on the line just drawn, and mark it b ; then a b on the board will represent 
the base line A B on the ground. Now set the sights in turn on the other 
points it is desired to fix, and, keeping the fiducial edge of the ruler 
against the pin at a , draw faint lilies to each of them. To prevent 
mistakes, these lines, called “ rays/’ should be marked with reference 
numbers indicating the object to which they are drawn, or the name of 
each object should be written against the line drawn to it. Having done 
this, place the compass on the table, and turn it about until the needle 
points exactly to the centre mark in the compass box, which will be 
magnetic north, then draw a dark line upon the paper, along the edge of 
the compass box, which can be afterwards used for orienting the table as 
explained (p. 105). 
Having drawn all the rays at station A, remove the table to station B, 
set it up and level it in the manner before described; then stick a pin at 
b, place the fiducial edge ol the ruler against it, and against a. Unclamp 
the table, and turn it about until the sights are directed on A, then 
clamp the table, and it will be in a position to continue the work. The 
process of pivoting the ruler against the pin, and directing the sights on 
the objects to be fixed, is to be repeated precisely in the same manner 
as at station A, and the points where the rays drawn from b intersect the 
