Engineer Compasses

What does an engineer compass allow you to do anything other than a regular bar?
It seems that if you have an e-compass and a map, can determine its location on the map. Find two points on the map and find your E-Compass. Draw precise lines and where they cross is where you are. The improved E-Compass the accuracy of their lines. A regular old compass just tells you which way is north.
Engineer Compasses
Engineer Compasses











