Description

The instrument consists of a partially hollowed-out disk mounted on a knee stand.

It is engraved on its circumference with a 360-degree scale with double numbering in reverse (each 10-180 X 2); the two diameters, adorned with foliage, bear the signature C. Langlois Au Niveau on the reverse.

Four non-folding pinnae, each with a slot and a window, are screwed onto the circumference.

The alilade, which rotates with the compass, has an index that points to the circular scale; it has two pinnae of the same type as the previous ones. The compass, which needle , is inscribed on its base with a sixteen-way compass rose with a fleur-de-lis to the north, the French names of the four cardinal points and the abbreviated names of four collaterals; around the compass rose, a scale of four times 90 degrees is engraved on a platform (O-90-0 X 2 from north).

Same model in Collection Scientific instruments Musee du Louvre INV OA 10691