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 Crucifix Dial The sides of the plinth are engraved with personifications of the four elements, 'IGNIS' with a hammer in his hand and a cannon in the foreground, 'TERRA' with a plough, 'AER' blowing a trumpet, 'AQVA' with a man pouring water from two vases. The front side of the cross (with the representation of fire) is hinged near the top and opens completely. It is engraved with a Crucifixion with 'INRI' at the top, and a skull and crossbones at the bottom of the cross, on one of the sloping sides. Underneath, a brass plate hinged at the bottom of the cross is lined on the sides and has a volvelle for converting hours. The rotating part of the volvelle is engraved with a scale of Italian hours from 1 to 24, divided to one, numbered by two. The index rotates on a scale of common hours, divided to the half hour by alternate shading, numbered 1 to 12 twice. The two sides of the cross are engraved with hour lines on the body of the cross, divided to the half-hour by alternate shading and numbered from 4, 5, from 7 to 11 and correspondingly IIII, V and VII to XI. On the other side the hour lines are divided in the same way and numbered from bottom to top 1 to 5, 7 and 8, and I to V. The top is engraved with a scrollwork and a scale of latitudes, numbered from 35 to 59 by three. A movable arm points to the latitude but is not attached to a mechanism for adjusting the latitude itself. The other sides of the arms are lined with a geometrical motif. The back side of the cross is inscribed 'TABELLA Ex qua cognoscit[?] quot horas et minuta nocturnus Lunae splendor efficiat' and a lunar volvelle. In the centre is a similar volvelle to the one on the other side. The rotating part of the volvelle is engraved 1 to 12 twice, numbered by two. The outer, fixed part of the volvelle has a scale 1 to 24, divided to one by alternate shading, numbered by one. Surrounding it is another ring with lunar days numbered from 1 to 291/2. Below the volvelle is a table for the difference between lunar and solar time according to the age of the moon. The table is inscribed 'D{IES} H{ORAE} M{INUTIS}'. On the sloping part, below the table is a coat-of-arms. Inside the cross, on the opening side of the cross, are two rectangular drawers lined with geometrical decoration. They could possibly be an inkpot and a pounce pot. On the top of the cross is a hinged round compass case, now slightly broken and with needle and glass missing. The bottom of the cross is inscribed with a table, 'TABVLA DOMINII PLANETARVM', with the hours of the day from 1 to 12 to 2 and of the night 3 to 12, and the respective ruling planets. The instrument was bequeathed by Maurice Rosenheim in 1922 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.34, no.73. Ilaria Meliconi |