UNIVERSAL EQUINOXIAL RING by Claude LANGLOIS,... Lot 113

UNIVERSAL EQUINOXIAL RING by Claude LANGLOIS, PARIS, ABOUT 1750. Brass instrument composed of a meridian circle and an equatorial circle: the meridian circle is engraved with the signature, two 90-degree scales for north and south latitudes, and seventeen city names with their latitude; the equinoctial circle is engraved, on the front, with two hourly scales of I-XII and, on the back, with fourteen city names with their latitude; the diametrical blade is engraved with sixteen city names with their latitude and embellished with an alidade engraved with the signs of the Zodiac. Signed on the meridian circle : "Langlois AParis aux Galleries du Louvre". Diameter : 17,5 cm Height with the ring : 22 cm 700/1 000 € Note: Claude Langlois, active from 1720 to 1756. Engineer in mathematical instruments and official supplier of the Royal Academy of Sciences, member of the corporation of founders of Paris. Reference: An almost identical ring by Claude Langlois is preserved in the collections of the Louvre Museum, diam. 15.5 cm. (OA 10164) Bibliography: Musée du Louvre, Département des Objets d'Art "Les instruments de mathématiques, XVIe-XVIIIe siècle" by Camille Frémontier-Murphy, RMN, Paris, 2002, p. 105-106, No. 59) described as follows: "The meridian circle is engraved with the signature, two 90-degree scales for north and south latitudes (divided into half degrees and numbered from ten to ten), and a list of latitudes (in degrees and minutes) of fifteen cities, twelve of which are European. On the perimeter of this circle, the suspension ring and its cursor are adjusted according to the latitude by sliding in two grooves. The equinoctial circle is inscribed, on one plate, with the time scale (I-XII X 2, with divisions up to 5 minutes) and, on the other plate, with a list of the latitudes of twelve cities, of which only six are European. In the axis of the poles, the diametrical blade with the latitudes of twelve other cities (of which six are European) carries in its center an alilade with pinnacles to aim at the Sun. This alilade is oriented according to the declination of the Sun in relation to the two arcs of a circle graduated, on one side, with the twelve signs of the zodiac (divided into three parts subdivided into two) and, on the other side, with the same scale with the initials of the months. Vegetal motifs decorate the diametrical blade, its alilade and the supports of the equinoctial ring."