细节
A 17th-century Dieppe ivory diptych dial
the circle of Ephraim Senécal (fl.1686-99)
unsigned and undated, black colouring throughout, dials all bordered with 'pecked' Dieppe ornamentation;
leaf 1a equinoctial dial 1-12 twice divided to the half-hour and polar dial (the ivory cracked), the hour lines parallel 8-12-4; leaf 1b scale to elevate dial 5°-80°, brass lunar volvelle (once silvered), the outer disc with the months engraved, the days punched (28 for Feuvier), 1-12 twice, the middle disc 1-30 with index arm, the upper disc with index arm and viewing window revealing silk for lunar phase on the disc below;
leaf 2a horizontal dial 5-12-7, magnetic azimuth dial 7-12-5, degree scale for compass, paper gazetteer for nineteen French towns, index arm;
leaf 2b date scale and perpetual calendar with engraved index-finger pointer;
Covered hole to left-hand side for pin gnomon (missing)
2¾in. (7.3 x 6.2 x 1.4cm.)