At a glance
Work and section read
Al-Biruni authored the full discussion of possible astrolabe constructions, Istiab al-wujuh al-mumkina fi sanat al-asturlab. This entry particularly records the Moon Box section edited, translated and technically discussed by Hill, not a complete reading of every chapter or a certain inventory of every instrument. It must not be merged with Ibn Abd al-Barr's unrelated biographical Istiab: similar titles do not identify one work 2.
Description, inheritance and modification
Hill associates the older machine with Hellenistic/Byzantine antecedents and leaves its original inventor unknown. The account mentions other craftsmen's variants before Hill attributes a concluding simplified proposal to the author. The work therefore links here to al-Biruni's proposed simplified gearing, not a claim that he invented every box or gear described 3.
Arithmetic and limits
The basic account lists eight wheels of differing tooth counts, manually advanced weekly input and representation of mean motions. The proposal attaches four teeth to the forty-tooth arbor, then meshes four with fifty-two, yielding364days in the engineering reading. The translation mentions360; this discrepancy is not erased by replacing the supposed author's number with the interpreter's result 4.
The28day sidereal lunar period differs from the29.5day mean phase cycle. Both are approximations, not guaranteed crescent visibility or exact daily celestial positions. The basic train yields about366.42days, not the proposal's output; fewer parts do not establish greater accuracy. The invention entry compares these by modern arithmetic while preserving the text's limits 5.
Witnesses and reading
Hill discusses manuscripts, figures and numerical differences, explicitly acknowledging partly inferred assembly. One variant gives327.72days in his calculation against399or359in witnesses, another354. These are questions of reading, attribution and interpretation, not merely mistakes we corrected in an Arabic original independently collated 6.
Actually read: English introduction139–142,translation156–158,commentary158–163,with158and163visually inspected. Not all Arabic apparatus or independent original witnesses. This entry establishes neither a surviving original machine nor manufacture of the proposal. It invents no composition day or transmission chain leading to every European clock 7.
Connections
People and things also explored
Al-Biruni, Muhammad ibn Ahmad· Al-Biruni's proposed simplified calendar gearing
Sources
- Hill — al-Biruni's mechanical calendar , pp.140,158,163
- Hill — al-Biruni's mechanical calendar , pp.139–142
- Hill — al-Biruni's mechanical calendar , pp.140,157–158,163
- Hill — al-Biruni's mechanical calendar , pp.156–163
- Hill — al-Biruni's mechanical calendar , pp.159–163
- Hill — al-Biruni's mechanical calendar , pp.141–142,163
- Hill — al-Biruni's mechanical calendar , pp.139–142,158–163
Cite this page
islam.museum contributors. “Full discussion of possible astrolabe constructions”. islam.museum, https://islam.museum/en/work/biruni-istiab-astrolabe/. CC BY-SA 4.0. Last updated 2026-11-06.
Improve this page on GitHub · Report an error · Help complete it · JSON