This is not a spelling mistake
Elements of Flight-Instruments
The ATTITUDE INDICATOR shows the aircraft's position in relation to the earth's horizon. The white semi-circle of the instrument represents the sky. The white dot at the center of the display represents the nose of the airplane in relation to the horizon and the whitel bars represent the wings of the airplane. In straight and level flight, the nose and wings correspond to the horizon line (see figure). At the top of the indicator is a marker and ball. The ball is covered by the marker indicating level flight. Although this instrument is used at all times, it is particularly important at night and when flying in clouds in order to control the position of airplane relative to the earth. See the examples given below for details.
http://www.allstar.fiu.edu/aero/images/main.gif
