Musées de Langres – Maison des Lumières Denis Diderot – Musée d'Art et d'Histoire

The sextant (one sixth of a circle) is a post 1757 variant of the octant (one eighth of a circle). In the second half of the 18th century, the combined use of a sextant and marine timekeeper made it possible to locate ships more precisely thanks to the addition of longitude to latitude measurements. The new data made it possible to calculate the coordinates of ships at sea, but also newly discovered lands, leading to significant improvements in cartography. The sextant was used widely from the end of the 18th century, and remained in use until the middle of the 20th century.