This instrument traces back to the oldest surviving astrolabes and features Latin engravings in the Anglo-Saxon script in addition to the Arabic-Kufic inscription. They probably date from the 14th century, as indicated by the use of Arabic numerals. Such Arabic-Latin astrolabes are frequently found.
The four inlay discs (tympana) are engraved with 6-degree altitude circles (almucantarats) and the lines of the unequal hours. They apply to the geographical latitudes 39°/36°, 33°/30°, 27°/24° and 21°/18° north and thus cover the geographical area of the Persian Empire. Latin translations are also found on the inlay discs.
Above the inset discs, the rete rotates with the eccentric ecliptic (with 3-degree division) and with 19 star points (see star list). As is usual with early Arabic instruments, a pointer (ostensor) is missing.
The border (limbus) shows four 90-degree divisions, marked from 5 to 5 degrees in Kufic Arabic script (Eastern number-letter system). There is no hour division, but there are small markings on the rim every 15 degrees. They serve to determine the time according to equinoctial hours.
The back of the astrolabe has a degree division at the top for measuring the altitude with the graduated pointer (alhidade) and two shadow or cotangent scales at the bottom: On the right, a scale based on the divisor 7 of the square side, on the left, a scale based on the divisor 12. Inside is the zodiac, associated with astrological scales and planetary symbols. The numerals are Arabic. A (solar) calendar circle is not present.
The complete description of the instrument as PDF for download
