then the balance is level. if the bubble is outside of this circle then the balance is not level. if you find a balance that is not level, carefully adjust the foot on each corner until the bubble is located in the center. in most cases, you should not attempt to move an analytical balance because they are very sensitive. if you do, then you will want to make sure the balance is still weighing correctly.
before you start, you should make sure that the inside of the balance is clean and dry. you should also make sure that all of the doors are closed when you are recording your masses. 