At sea, the natural horizon is used to align the sextant horizontally. For measurements on land, AstroMedia has created a clever substitute: The Artificial Horizon allows comparatively accurate measurements of a point above the mathematical horizon even when it is not visible in the form of the chine, as on the coast or at sea. With the help of a third mirror, a spirit level and the stamped cardboard components, the height can be measured independently of the natural horizon.
How it works: To determine the height of a point (celestial body, mountain peak) above the mathematical horizon, you have to control the horizontal position of the sextant throughout the measurement by looking at the spirit level. You do not need to look at the unmirrored image, but get the mirrored image with the aimed point by swivelling the alidade to the height of the marked line on the horizon mirror. Then make sure that the sextant is horizontal and read off the result.
