Museum- Claude Langlois Full Surveying Circle At Level 21 Cm

“The instrument consists of a partially hollowed-out disc 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, on the reverse, the signature of C. Langlois Au NIveau... Four non-folding pinnules, 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, with the needle at its center (possibly posterior), is inscribed on its base with a sixteen-direction 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).” (Frémontier-Murphy, 2002, p. 283)

Same model in Scientific Instruments collection in Louvre Museum