Astrolabe by Hans Bamman
Record status
Individual type · partial
Period
1490
This brass planispheric astrolabe, dating to 1490 and measuring 140 mm in diameter, is the work of maker Hans Bamman. Only the mater of this instrument currently survives.
The piece features a throne with a shackle adorned by rose decoration on both sides and includes a suspension ring. The limb contains a degree scale from 0 to 360, while the outer rim is marked for hours in two sets of 1 to 12. The back of the mater displays an intricate arrangement of scales including a degree scale, a zodiacal scale with names and symbols, a scale for 28 lunar mansions, and an eccentric calendar scale for accounting for the sun's progress.
Centrally, the instrument is etched with a double shadow square and a diagram for unequal hours. It is signed with the mark 'h b' along with the maker's distinctive triangular mark.
Evidence at a glance
- Linked sources
- 1
- Photograph views
- 1
- Catalogue references
- 0
Counts describe this entry’s documentation, not authenticity, rarity or completeness. Photographs may show one specimen; check each caption and licence.
Technical characteristics
- Date
- 1490
- Type
- German astrolabe
- Maker
- Hans Bamman
- Origin
- German
- Diameter
- 140 mm
- Signature
- h b with triangular mark
- Place recorded
- Germany
- Maker / attribution
- Hans Bamman
Design
- Visible features
- • The instrument features a throne with a rose-decorated shackle. • The back plate is circular with a central hole for an alidade or rule pivot. • The outer rim is graduated for degree measurements. • The object exhibits visible surface patina and wear marks throughout the brass plate.
- Identification and Attribution
- The instrument is dated to the year 1490 and carries the signature of the maker. The identification is confirmed by the initials 'h b' engraved on the surface, accompanied by a specific triangular mark associated with Hans Bamman. The object remains in the collection of the Museum of the History of Science, Oxford, under inventory number 46769. The information provided serves as the primary record for this item, emphasizing the survival of the mater as the sole remaining structural component of what would have been a more complex assembly including the rete and various climate-specific plates.
- Structural Design of the Mater
- The surviving mater of this 140 mm diameter astrolabe consists of a back plate integrated with a limb. The structural integrity of the instrument is maintained by a throne located at the top, which incorporates a shackle featuring rose decorations on both sides and a functional suspension ring. The limb itself is marked with a comprehensive degree scale ranging from 0 to 360, divided into 5-degree increments and subdivided into 1-degree units, with markings numbered by 10. The perimeter of the rim is further divided to accommodate an hour scale, which is presented as two sets of 1 to 12. The construction is strictly of brass, maintaining a consistent circular form that housed the missing internal components.
- Astronomical and Calendar Scales
- The reverse side of the mater is heavily engraved with multiple concentric scales designed for astronomical calculation. The outermost ring is a degree scale (90-0-90-0-90) used for altitude measurement. Moving inward, the zodiacal scale provides names and symbols for the twelve signs, each paired with a 30-degree scale. A significant feature is the inclusion of a scale of 28 lunar mansions, representing the zodiacal sections occupied by the moon. The innermost scale is a calendar, which is purposely eccentric. This eccentricity is positioned offset relative to the zodiacal scale to reconcile the sun's apparent motion along the ecliptic over the year. Additionally, the central area of the plate is occupied by a double shadow square, containing scales 0 to 12, and a geometric diagram dedicated to calculating unequal hours.
Identification
- Inventory Number
- 46769
- Source note
- Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.
Catalogue references
No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.
Research required
- Research required: The source notes that only the mater of the instrument survives, meaning other components like the rete, alidade, and plates are absent.
- Research required: The specific identification of the 'h b' initials with Hans Bamman relies on the presence of a triangular mark attributed to him by the museum.