Ring dial

Forged ring dial for 45° North. This instrument has a suspension loop but no ring. On the outer face is a zodiac scale set either side of the slit. Various inscriptions surround an engraving of a cock on a shield set in a diamond: 'Dum Sol amicus hora dico secure' (When the Sun is friendly I tell the hours surely); 'Joan Paulus Gallucius Saloentis sua manu f. Venetiis 1564'. The inner face carries a date scale set either side of the slit. Declination lines are drawn parallel to the rim, divided from Tropic to Tropic by zodiac sign and marked by symbol. Curved hour-lines are drawn across the declination parallels and there is a further inscription: 'Toramen mobile secundum singula signa Zodiaci uel qualibet diem ad Latitud 45°' (Slider moved according to single sign of the zodiac or the day, whichever you please, for latitude 45°). A nickel strip acts as the gnomon.

A burin was used for engraving the numerals and lines on this instrument, but the technique was extremely poor. Despite the date of 1564, the list of dates for the sun's entry into the zodiac signs is given according to the Gregorian calendar (and all dates are given as the 21 of the month, which is incorrect). The use of long final 's's is also incongruent with a 16th century date. Like AST0374, it purports to have been made by Giovanni Pauli Gallucci.

Object Details

ID: AST0274
Collection: Astronomical and navigational instruments
Type: Ring dial
Display location: Not on display
Creator: Gallucio, Joanne Paulo; Unknown
Date made: 1900-1950; 1900-50
Credit: National Maritime Museum, Greenwich, London, Caird Collection
Measurements: Overall: 23.5 x 65 mm