This device has a circular wooden base, with a slightly conical section and a turned foot in the centre. On top there is a semi-circular iron band which is holding a bronze circle, with a rectangular, almost flat, transversal section with three concentric lines engraved in it. On the inner perimeter it has a calibrated millimetric line, on the next line it has a scale for the numbers from 0 to 90, which themselves appear on the following line. This numbering is divided into four segments. Inside this circle is another vertically-orientated circle, made of a narrower strip, which also has a numbered scale. Inside this, is a spherical structure made up of three horizontal and two vertical rings. Inside them, at the top of a vertical shaft is a small globe, with a map of the Earth. The horizontal rings represent the Equator and the two Tropics (the polar circles are missing); the vertical rings mark the two colures of the Equinoxes. All the rings have a calibrated line printed on each side and the names of what they represent. At the level of the North Pole pointing inwards, there is a top leading to two semi-circular metal strips, each of which ends in a small circle representing the sun and the moon, which are depicted with human faces drawn on paper.
This apparatus was used in schools to teach astronomic geography. The rings show the Earth’s most important circles in their relative positions and as if they were in space. This enabled the children to understand the movement of the moon and the earth in relation to the sun.