Mechanical equinoctial and declinatory dial... - Lot 4 - Tessier & Sarrou et Associés

  2. Result
  3. Mechanical equinoctial and declinatory dial... - Lot 4 - Tessier & Sarrou et Associés
  4. Lot n° 4 
Lot n° 4
Go to lot
Estimation :
10000 - 15000 EUR
Mechanical equinoctial and declinatory dial... - Lot 4 - Tessier & Sarrou et Associés
Mechanical equinoctial and declinatory dial in brass, rectangular plate with cut sides on four wedge screws. Plumb bob holder in the shape of an A (the bob is missing). The plate is bordered by two Latin inscriptions, "latus in muro meridionalis applicandum" (side to be applied to the south wall) and "latus in muro septontrionalis applicandum" (side to be applied to the north wall). Between these two inscriptions, a circular plate engraved with a compass rose (with 32 named directions) rotates within a 360-degree scale (divided at one degree into four quadrants). The scale is engraved on the plate with Latin indications for their declinations. In the upper part, a circular serrated hour dial is mounted between two supports. The minute dial turns around the central dial (the needle is missing) to aim at the sun by means of the summit alidade. The circular plate engraved with the places, the plate with a zodiac calendar and the alidade are later. Germany or Central Europe, first half of the 18th century H. 23 cm W. 24 cm D. 16 cm Provenance : - Sale Roussel Collection, 13-14-15 March 1911, Drouot Paris, lot 198 - Gertrude HAMILTON Collection, n°135, reproduced under figures 135 Fig. I and Fig II. In spite of the modifications (notably the zodiacal calendar detached from a probably Italian instrument), this dial remains of the highest interest as it is the only example currently known where the functions of an equinoctial dial are combined with those of a declinator. Mechanical equinoctial dials were developed at the end of the 17th century and enjoyed a certain popularity in southern Germany and central Europe for their very accurate direct time reading (to one minute or less). Several specimens of various forms are in the National Museum of Technology in Prague, in the Huelsmann Collection in Bielefeld and a beautiful series was at the time, part of the collections of the Time Museum, Rockford The declinators designed at the same time were used to measure the eastern or western declination of a vertical surface on which a dial was drawn. A side of the instrument is placed on the wall adjusted for the latitude and altitude of the sun. At noon, the orientation of the instrument indicates on the compass rose the declination sought (see the description in Nicolas Bion, Traité de la construction et des principaux usages des instrumens de mathématiques, 1709, 304-5, plate 25, figure 3). EXPERT : Anthony TURNER - 06 80 20 44 97
My orders
Sale information
Sales conditions
Return to catalogue