A tool used to determine both how level a horizontal surface is and how
plumb a vertical surface is. Most spirit levels are made of tough, lightweight
metals such as magnesium or aluminum. The spirit level has two or three
slightly curved glass tubes or vials, almost filled with ethyl alcohol (used
because of its low freezing point), which measure either plumb (vertical)
or level (horizontal). The amount of liquid in each vial is not enough to
fill it, so there is always a bubble in the vial. When the bubble is centered
between the lines on the vial, the surface is either level (exactly horizontal)
or plumb (exactly vertical), depending on the vial.
The spirit level is the most commonly used level in the construction trade.
Different types are used by carpenters, stone masons, bricklayers, other
building trades workers, surveyors, and millwrights. Other types of levels
include electronic levels and