Brass Bowl

A heartening sight. Surveyors working on the streets. Somebody wants to know where a property line is. Usually when this happens, things get built. What you see here is a Back Sight (Triple Prism) set up on a known point. The man in the distance is also set up on a known point, and after sighting on the Back Sight and establishing a base angle, he has swung around and is now shooting a laser beam to the Rod, being held by the Rod Man to establish a new point.

At least, this is how I remember it being explained to me. If I’m wrong, please add a comment and let us in on the real story.