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Ivory diptych sundial, Charles Bloud. C 1660/1670.
Rectangular ivory diptych sundial with two leaves engraved, in black on each face, with a double-lined frame with typical Dieppe ornamentation along edges and various dials.
The upper face of the lid has two dials, an equinocital dial and a polar dial. The circulair hour scale of the equinoctial dial, for use in spring and summer months, is numbered 1-12 twice. The polar dial has two hour scales numbered 8-12-4 and a central brass rivet with hole for the missing pig-gnomon ( brass clasp on the left side of the base plate to hold gnomon rod)
The nunderside of the lid has a pewter lunar volvelle with several scales, numbered 1-30 (inner), 1-12 twice (middle) and 10-20-30 for each month (outer) from “janvier” through “decembr”. The small rotating disc in the centre has an index and a circular window showing the lunar phases. A latitude scale along right side from 0 to 80 degrees to set the right angle for the dials of the upper face of the lid.
The upper face of the base-plate is a horizontal dial with a green string gnomon and a single hour-scale for approximate latitude of 48, numbered 5-12-7. Inside the hour-circle, a magnetic azimuth dial ( analenmatic with a pewter elliptical scale, numbered V-XII-VII) associated with the compass(printed paper rose wind with 32 directions). A slot in the centre allows the adjustment of the analemme according to the date (showed by a disc on the other side). A blued-irom needle with brass pivot and a glass over all.
The underside of the base-plate has a pewter volvell with perpetual calendar scale to set the date for the magnetic azimuth elliptical hour-scale inside. It is engraved with inscription “Fait et inventic par Charles Bloud Ã¡ Dieppe”. An index in the form of a hand is engraved. Brass hooks and comes with a case. This diptych is described in the Catalogue ofÂ Cadrans Solaires / Sundials by Dominique & Eric Delalande.
Reference: Cadrans Solaires / Sundials by Dominique & Eric Delalande.