astrolabe
- Museum number
- 1914,0219.1
- Description
-
The MATER of this brass astrolabe is empty except for some construction markings. The RIM, which is soldered to the back plate, has an equal 24-hour scale calibrated by letters instead of numerals (A, B, C, D, E, F, G, h, I, k, L, M, N [reversed], O, P, Q, R, S, T, V, X, Y, Z) and a 360° altitude scale, numbered 0° to 360°.
The THRONE is trilobal.
On the RETE with its distinctive Y inside the ecliptic, 23 stars are indicated, some names now illegible. The star pointers are partly zoomorphic (dragon's head and dog's head), partly flamelike and partly in the form of bent swords.
The star names are given as follows: [illegible], 'Batukaito', 'Algenib [?]', 'Menkar [?]', 'Aldeb', 'Alaior', 'Rigil', 'Algomeiza', 'Alhabor', 'Vrsa', 'Alfard', 'Corvus', [illegible], 'Alram', 'Alchim{e}c', 'Alacrab', 'Elfeca', 'Al[illegible and broken off]', 'Wega', [illegible], 'delfin', 'Denebalgedi', [illegible].
The ecliptic bears the usual Latin names of the zodiacal signs, each sign is divided to 30°.
The three PLATES have markings for the equator and the tropics, azimuths for every 22½°, almucantars for every 2° (numbered by 6°), and curves for the unequal hours (numbered 1 to 12). They are laid out and marked for the following latitudes: 1a) 'Dover’ 51°; 1b) 'Oxoni{ensis}’ 52°; 2a) 'Notinghm’ 53°; 2b) 'Ebo’ [York] 54°; 3a) 'Novucas{trum}’ [Newcastle] 55°; 3b) 'Berwik’ 56°.
The BACK has several circular concentric scales as follows (from the outside):
1) a 360° altitude scale, marked four times 0° to 90° starting at the east-west line;
2) a scale with the usual Latin names of the zodiacal signs (except 'Wirgo'), each sign divided to 30°;
3) a Julian calendar scale marked with the usual Latin names of the months, each month divided to the corresponding number of days; the equinoxes corresponding to March 11 and September 13;
4) to 6) three bands with the names of saints and feast days, the corresponding dates and the corresponding day letters, amongst which are the English saints Dunstan (19 May) and Augustine of Canterbury (26 May).
The lower half of the vacant space inside these circles is taken up by a double SHADOW SCALE to the base 12.
The counterchanged RULE and ALIDADE as well as the SCREW and the PIN are modern replacements. All except the screw are marked '1888', the year of their replacement.
- Production date
- 15thC-18thC (previously dated to c. 1450, or to c. 1375, but more likely to have been made later)
- Dimensions
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Diameter: 123 millimetres
-
Thickness: 6 millimetres
- Curator's comments
- The design of this astrolabe has suggested links between it and the diagrams in Geoffrey Chaucer's 'Treatise on the Astrolabe'. However, details including the mounting of the ring indicate that this astrolabe was made following the diagrams in Chaucer's text, and therefore is likely to post-date the late-14th century date of its composition. Catherine Eagleton, "Chaucer's own astrolabe" : text, image and object'. Studies in History and Philosophy of Science, 38:2 (2007), 303-26, discusses this and other astrolabes usually linked to Chaucer, concluding that they are more likely to date from the 15th-18th centuries than to an earlier period.
- Location
- Not on display
- Exhibition history
-
Exhibited:
2009 11 Dec-2010 10 May, Madrid, Canal de Isabel II, Treasures of the World's Cultures
2009 1 May-20 Sep, Victoria, Royal BC Museum, Treasures of the World's Cultures
- Condition
- Latest: 2 (Jul 2015)
- Acquisition date
- 1914
- Department
- Britain, Europe and Prehistory
- Registration number
- 1914,0219.1