Travelling sundial / compass-sundial in tortoiseshell horn box

Horizontal travelling sundial in a square box with lid. Inside the lid is a rotating plate that indicates the rising and setting of the moon, as well as the months, days, and night length. On the outer bottom, an engraved small hand can be adjusted to the month of the year. Nearly square sundial consisting of two parts. The bottom section contains a compass with an eight-fold compass rose, a division in 0-90-0-90 degrees, and an elliptical silver ring with a division in VII-I, XII-V hours. On the compass rose are also written the names of a number of French places with their corresponding latitudes. On the back of the bottom part is a rotatable silver disc with a central square subdivided into 49 smaller squares with a numeral (from 0 to 31). Along the edge is a division of months and days. The correct date can be set by rotating the disc. An engraved hand serves as an index. Rotating the disc simultaneously shifts the silver ring in the compass (vertically). To the right of the compass is a folding pin that, when using the instrument as a vertical sundial, is unfolded and set against the lid. According to the 19th-century description, a cord, as usual with an 'ordinary' sundial of this type (cf. the German 'Klappsonnenuhr'), was also present. However, nothing of such a cord is visible in depictions of Bloud sundials. This is therefore a 'çardran magnetique'. The needle of the compass indicates the correct hour. What is missing is the small brass peg, which must have sat in an opening on the side. The opening can be closed with a hook. A lunar dial is applied to the underside of the lid. The fixed silver disc indicates the month and a division into 2 x 1-12 hours. The two rotating discs indicate the day and the lunar phases. On the right side is a vertical scale with latitudes from 0 to 80 degrees. The pin can be folded out against this so that the lid is set at an angle. The top of the lid then serves as a vertical sundial. On the circular border is a division into 2 x I-XII hours. The peg from the side would probably have to be inserted into the small hole above XII. The Rijksmuseum, Amsterdam, holds this object as NG-KOG-1690; its record gives material recorded as tortoise shell, paper, silver (metal), glass; technique cutting, glue, gild, engraving, nailed; measurements length 9.8 cm x width 9.2 cm x height 1.5 cm. Description translated from the museum's Dutch catalogue text; details are those of this museum object, and how far it represents a wider type has not been independently verified.