Equinoctial Sundial Signed Langlois In Paris Datable Circa 1740

Brass equinoctial sundial of octagonal shape. Five city latitudes on the base plate and the signature "Langlois A Paris aux Galleries du Louvre". The bottom of the compass is silver plated and engraved with a compass rose with sixteen directions and the four cardinal points. Original blued steel needle with brass pivot. The hour circle is graduated on the top in Roman numerals from 3 to 12 and from 1 to 8, and on the inside in Arabic numerals from 4 to 12 and from 1 to 8. The underside of the hour circle is engraved with six cities and their latitudes, with the rotating gnomon at its centre. The mobile arc of the latitudes is graduated from 0 to 70. The underside of the base plate is engraved with numerous cities with their latitude, some of which are very rare: "Isle of Iron" (El Hierro), "Portobello" (Panama), "New Orleans", "Cape B. Esper" and "Archangel" (Russia).
Note : this sundial is a traveller's sundial with notably the Iron Island, Archangel (Russian port on the White Sea) and Portobello (port city located in Panama which was the most important colonial port from where Spain sent most of its wealth to Europe in the 16th and 17th century).
Dimensions: 9 cm x 9 cm. In its black chagrin case with red velvet interior.
Paris dated around 1740 (according to the address).