Construction and Design
The astrolabe is composed of a mater formed from two soldered brass layers, creating the base for the limb and the throne. The throne features scrollwork and floral decoration, while the suspension system uses a shackle and two rings. The limb is divided into two concentric circles, with the outer circle containing degree markings and hour divisions, and the inner circle featuring quadrant divisions.
The instrument includes three internal plates engraved with meridians, equator lines, and tropic markers. These plates also display latitude engravings, including specific markings for Nuremberg at 49 degrees 27 minutes. The rear of the mater features additional circular scales for zodiacal signs and a calendar, surrounding a central shadow square and the Laudian coat-of-arms.
Evidence for this section
- “The mater of the astrolabe is made of two soldered layers of brass, one for the plate and the other for the limb and the throne.”
- “The throne is decorated with two flowers resting on scrollwork and is filleted on the sides.”
- “The third plate is engraved for 'LATI LIII' and on the other side for 'LATI LIIII'.”
Provenance and History
The astrolabe was documented in England by the seventeenth century, where it entered the collection of Archbishop Laud. This ownership is confirmed by the presence of his coat-of-arms on the back of the instrument. The archbishop's arms are those of the archbishopric of Canterbury combined with his own heraldic devices.
The instrument currently exhibits a darkened, black exterior surface. This coloration is suspected to be a result of long-term exposure to atmospheric conditions, specifically the environment of a nineteenth-century gas-lit room. While the exterior and some internal areas show this effect, the inner surfaces of the plates remain unaffected by this process.
Evidence for this section
- “This astrolabe by Georg Hartmann of Nuremberg was in England by the 17th century when it came into the possession of Archbishop Laud, whose coat-of-arms now appears on the back.”
- “The instrument is completely black on the outside, due probably to atmospheric conditions, such as a gas-lit room in the nineteenth century”
State of Preservation
The instrument is incomplete, with several key functional components missing. Specifically, the rete, pin, and wedge are absent from the central assembly. Additionally, the rule and alidade, which are necessary for taking measurements using the instrument, are not present.
Despite the absence of these parts, the primary brass structure of the mater and the three plates remain intact. The engraved details, including the latitude lines, zodiacal scales, and signature, remain visible, and the overall dimensions of the 162 mm diameter frame are maintained.
Evidence for this section
- “The rete , pin and wedge are missing.”
- “The rete, rule and alidade are missing.”
