100 A MANUAL FOR NORTHERN WOODSMEN 
Another method of working is by intersections. For 
this, it is necessary to have two known points or a measured 
base. The instrument is set up at one of the known 
points, and, the afidade being pointed at the other, a line 
is drawn and the known distance scaled off upon it. 
Then, from that end of the base line representing the 
point occupied, rays are drawn in the direction of other 
well-defined objects on the shore which it will be desir¬ 
able to locate. Flags may be used to define them, but 
natural objects will often suffice. The instrument is then 
