The dial is in the form of a book with clasps. The upper leaf is badly cracked next to the hinge. The outer side of the upper leaf has a wind rose with 32 directions numbered by two from east in alternate red and black ink. The cardinal directions are named 'SEP', 'ORI', 'MER', 'OCCI' and outside the wind rose in the form of petals are engraved eight main directions 'nort', 'nort ost', 'ost', 'suid ost', 'suid', 'suid west', 'west', 'nort west'. There is a compass viewing hole and a brass arm in the form of a hand. Around the wind rose is inscribed 'WEGWEISSER' and 'COMPASSVS' in red and black ink. In the corners are three brass plates (one missing) with bun feet and on the opening side are two catches.The inside of the upper leaf has a pin gnomon dial (pin missing) for 'QVANTITAS DIEI' numbered from 8 to 16 and with the symbols of the zodiacal signs, filled with alternating red and black ink. Below is a vertical string gnomon dial (string missing), for common hours from VI to XII to VI in red, inscribed in a blue triple lined circle.
The inside of the lower leaf has a compass with magnetic deviation marked and the cardinal points inscribed 'S', 'ORI', 'M', 'OCCI'. The dial is partially inscribed in a triple-lined square, together with a pin gnomon scaphe dial for Italian hours marked from 9 to 24 and numbered from 8 to 24 in red. A metal loop passing through a hole in the leaf from side to side and centred on the lunar volvelle on the back looks like a later addition. Below is a twelve-petalled flower. Inside the square is a decoration of sun, clouds and stars. Along the edge of the leaf is a string gnomon dial for common hours marked from 4 to 12 to 8.
The outside of the lower leaf has a lunar volvelle (brass volvelle missing), with hours marked from 1 to 12 twice and days marked from 1 to 291/2. In the centre is a decoration and sun effigy. The whole volvelle is marked in red and blue ink. The edge of the leaf is lined and there are four brass plates in the corners, with four bun feet. Next to the hinge is the maker's mark (a crowned snake) and initials 'H T'. On the hinge is a ring for suspension, and on the opposite side of the lower leaf is a hole for stowing the pin.
The instrument was purchased in 1896 and is described in F. A. B. Ward, A Catalogue of European Scientific Instruments in the Department of Medieval and Later Antiquities of the British Museum (London, 1981), p. 38, no. 87.
Ilaria Meliconi
