Why automatic level is called automatic level?

Answer 1

Sometimes people call it self leveling. Its not really either. If you look at the bullseye bubble on the level, as long as its halfway in the circle, the line of sight won't change. This basically because of comething called a compensator which is a Prism usually suspeneded by wires and maintains the same angle as long as that is within the bubble described, Surveyors like it because if you walk around a tripod and the ground settles a little bit, you won't have to adjust the thumb screws...