All the markings of this brass astrolabe are in Hebrew script.
The rim of the MATER has a 360° altitude scale numbered in alphanumerical notation (where letters stand for numbers) clockwise by 10° starting at the throne, leaving the hundreds out. The rim is rivetted to the backplate. The inside of the rim has a recess at 12 o'clock underneath the throne to accommodate the tongues of the plates. The inside of the mater is engraved with several circular scales in two sets as follows (from the outside):
1) the numbers from 1 to 28 anti-clockwise in alphanumerical notation, standing for the 28 years of the solar cycle when the first day of the year falls on the same week day and the pattern restarts.
2) the corresponding weekdays numbered 1 to 7 in alphanumerical notation indicating the first week day of that particular year
3) the Hebrew letter 'כ' (meaning 'Kabush' or leap year) at every fourth year indicating leap years.
1) the names of the months in Judaeo-Arabic in Hebrew script as follows (in transliteration): 'Yanir, Febrir, Mars, Avril, Mayah, Yunyah, Yulyah, Agust, Setenber, October, Novenber, Dejember';
2) the corresponding 'Pashut' (dayletters for ordinary years) in alphanumerical notation: 3, 6, 6, 2, 4, 7, 2, 5, 1, 3, 6, 1. These numbers indicate the day of the week of the first of each month.
3) the corresponding 'Kabush' (dayletters for leap-years) in alphanumerical notation: 3, 6, 7, 3, 5, 1, 3, 6, 2, 4, 7, 2.
The THRONE has a pierced design composed of three quatrefoils made up of three layers of metal.
The RETE has a semi-quatrefoil design with the star-pointers in the shape of bent daggers sitting on single or triple lobes. Two little knobs are attached to both sides of the double counterchanged equinoctial bar which act as handles to turn the rete. 24 star names are given partially in Hebrew, partially in Judaeo-Arabic in Hebrew script. One star-pointer on the left-hand edge of the equatorial circle is marked 'en zeh kokhav' ('this is not a star'), thus indicating a dummy pointer whose sole purpose is to offer aesthetical balance.
The ecliptic is marked with the Hebrew names of the zodiacal signs which are divided around the rim into sections of 30°with subdivisions of 5°.
Starting from the vernal equinox, the star names are inscribed in a mixture of Hebrew and Judaeo-Arabic, all in Hebrew script, and appear as follows:
Beten Qitus; En zeh kokhav; Rosh ha-Shor; Al-Dabaran; Regel Teumim; 'Ayyuq; Al-'Abur; Al-Gumitza; Yad ha-Dov; Zenav ha-Kelev; Regel ha-Dov; Lev ha-Aryeh; Kenef ha-'Orev; Al-A'zal; Al-Ramih; [name unclear]; Tzevar ha-Hayah; Lev ha-Aqrav; Nofel; Ha-Nesher ha-me'ofef; [name unclear];Eqev ha-Sus; Zenav ha-Gedi; Shekhem ha-Sus; Zenav Qitus.
The 5 PLATES are marked on both sides with the circles for the equator and the tropics, azimuths for every 10°, almucantars for every 5° (numbered only on plate 3b in alphanumerical system) and the lines for the unequal hours (numbered only on plate 3b in alphanumerical system). The ten sides are marked in alphanumerical notation and laid out for the following latitudes: 1a) 33°; 1b) 43°; 2a) 35°; 2b) 42°; 3a) 36°; 3b) 40°; 4a) 37°; 4b) 41°; 5a) 38°; and 5b) 39°.
The BACK of the instrument has several circular scales as follows (from the outside, all numbers in alphanumerical notation):
1) a concentric altitude scale marked twice 0° to 90° starting at the east-west line culminating at the throne. The lower half is blank.
2) a concentric scale with the Hebrew names of the zodiacal signs, each sign divided into 30°, labelled every 10° and subdivided into 5 and single degrees;
3) an eccentric calendar scale with the names of the months in Judaeo-Arabic in Hebrew script as given on the mater (apart from 'Setenber' which is now 'Setember'), divided into the corresponding number of days and labelled every 10 days with the correct number of days for each month, subdivided into 5 and single days. The equinoxes correspond to March 11½ and September 15.
The bottom half of the vacant space inside these circles is taken up by a double SHADOW SCALE marked 'tzel yashar' (straight shadow) and 'tzel haphukh' (inverted shadow) to the base of 12, every fourth digit numbered. The top half contains two HORARY QUADRANTS for unequal hours.
The ALIDADE is counterchanged without any markings and with one hole in each sighting vane.
- Height: 11 centimetres (includes the throne)
- Thickness: 0.4 centimetres (MATER plate)
- Thickness: 2.18 centimetres (fully assembled)
- Diameter: 9.2 centimetres
This exquisite small astrolabe with quatrefoil decoration is one of the very few known instruments of European origin with markings in Hebrew.
Other instruments with Hebrew markings are in collections in Chicago and Paris. The BM instrument is neither signed nor dated, but the style and the month names used suggest it might have been made in 14th century Spain or Italy.
See Bernard R. Goldstein, The Hebrew Astrolabe in the Adler Planetarium, Journal of Near Eastern Studies 35, 1976, 251-260 (repr. in B. Goldstein, Theory and Observation in Ancient and Medieval Astronomy, London 1985, paper xix) with detailed discussion of the BM instrument.The detailed markings on the plate for 40 degrees may indicate that the instrument was constructed for this latitude which would include places such as Toledo and Naples, for example.
2015-2016 May-May, HOTW, tbc. PROMISED
2014-2015 Dec-Mar, HOTW, tbc. PROMISED
2014 Mar-Jun, HOTW, tbc. PROMISED
6 July 2009
Reason for analysis
Report on the scientific examination of an Astrolabe with Hebrew inscriptions P&E 1893,0616.3
This astrolabe is unusual in being inscribed in Hebrew script but in the Arabiclanguage. A scientific examination was carried out to contribute to the understandingof this rare piece, which is one of the hundred objects chosen to illustrate A History ofthe World. The instrument is a bright golden colour and is described in Merlin as giltbrass. XRF analysis was used to clarify this description. Microscopic examination andradiography were carried out to investigate the techniques used in its manufacture.All the components of this astrolabe were made from brass with approximately 10%zinc and 5% tin as deliberate additions to the copper, the other elements detectedbeing accidental impurities. No gilding is present, the golden colour being attributablepurely to the high polish of the brass. The markings are all engraved. The mater isconstructed from a cast back plate and separately cast rim, held together with rivets.The throne has an additional component, adding depth to the openwork decoration.The five latitude plates were made of hand-forged sheet brass. All these features areconsistent with a medieval date.
Analysis reference number
Prehistory and Europe
Astrolabe; gilt-brass; engraved with Hebrew characters; a) mater rim graduated 0-360 degrees clockwise; Moorish style rete; pierced mounts; 25 star-pointers; outer ring of womb: numerals for years of solar cycle; 5 plates; almucantars every five degrees; azimuth lines every 10 degrees; lines of unequal hours of the night; b) dorsum; outermost ring with half graduated; ring with zodiac signs; ring of days and months; equinoxes at 11 March and 15 September; upper half: lines of unequal hours; lower half: 2 shadow squares.
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Object reference number: MCC3708
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