Ivory diptych sundial, Charles Bloud. Dieppe, c. 1660/1670.
signed on the silvered-brass calendar volvelle Fait par Charles Bloud Dieppe, the upper face of the lid with pin gnomon dial the quarters decorated with scrolls, the inner face of the lid similarly decorated, with white-metal calendar volvelle, latitude scale and string gnomon, the horizontal face with pierced azimuth ellipse with hour scale engraved with Roman numerals, the engraved paper compass dial with latitudes of continental cities (needle and glass missing), with folding latitude arm, the underside with the signed calendar volvelle, further decoration and hand and finger pointer, with two hooks and eyes, the pin gnomon and hook keep missing — 31/8in. (7.9cm.) long 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 equinoctial 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 underside 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-iron needle with brass pivot and a glass over all.
The underside of the base-plate has a pewter volvelle 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 á 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 of Cadrans Solaires / Sundials by Dominique & Eric Delalande.
Reference: Cadrans Solaires / Sundials by Dominique & Eric Delalande