The Sole Known Astrolabe Of An Important Iranian Instrument Maker

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Location
London
Lot Number
27

The Sole Known Astrolabe Of An Important Iranian Instrument Maker

The sole known astrolabe of an important Iranian instrument maker, Muhammad Husayn ibn Muhammad Bâqir al-Yazdî, dated 1057 H [= 1647/48]

Catalogue Note

This is a historically significant piece the maker of which is possibly to be identified with the Muhammad Husayn who made one of three surviving world-maps engraved on circular brass plates that caught the attention of the scholarly world some 20 years ago.

The mater is low and plain. The rim is divided and labelled for each 5°. The rete is distinguished by a full circular frame for the equinoxes, rare on Safavid instruments. Its purpose is simply to support star-pointers. The names of the 24 stars counter-clockwise in the four quadrants beginning on at the vernal equinox on the left are:

kaff al-khadîb / dhanab-i qaytus (shimâ)lî / ghûl / ‘ayn al-thawr / ‘ayyûq / rijl al-jawzâ’ al-yusrâ / yad al-jawzâ’ al-yumnâ // yamâniya / shâmiya / fard / qalb-i asad / ? (hidden by horse) / janâh al-ghurâb // a’zal / râmih / nayyir al-fakka / qalb (al-‘aqrab) / ‘unuq al-hayya / ra’s al-hawwâ’ // wâqi’ / tâ’ir / ridf / fam al-faras / sâq-i sâhib al-mâ’

There are two original plates, one for latitudes 32° and 34° and the other for 40°0′ and 42°0′. The lengths of longest daylight are given respectively 14h7m, 14h17m, 14h51m and 15h6m. (For obliquity 23°35′, the standard value amongst Safavid scholars, these are in error by 0, 0, -1 and +1 minutes.) There are altitude circles for each 3° and no azimuth circles.

The mater is engraved with four sets of half-horizons for each 8° of latitude from 12° to 84°, 14° to 86°, 16° to 88° and 18° to 90°.

The third plate is different from the other two and is surely by another maker, who has added a date 1197 H [= 1783/84]. The crude incision for the hole at the bottom of the plate confirm that we are dealing with another maker. This plate bears astrolabic markings for latitudes 21°40′, for Mecca (Makka-yi mukarrama), and 24°40′, for Medina (al-Madîna). The length of longest day is given only for the former, namely, 13h19m28s, accurately to minutes 13h20m). There are altitude circles for each 3° and azimuth circles for each 5° above the horizon and each 10° below it.

The upper back bears a trigonometric quadrant with horizontal lines for each unit up to 60, as well as a solar quadrant with markings for the altitude of the sun in the azimuth of the qibla throughout the year. The cities represented are Kufa, Mosul, Samarra Basra, ?, ?, Isfahan, Astarabad, Yazd, Tus, Nishabur, Shiraz, Qandahar and Multan, and the Persian inscription relates to the use of these curves.

Below the horizontal diameter is a double shadow square to base 7 (aqdâm, feet) on the left and 12 (asâbi’, digits) on the right. The alidade is plain and cannot be original. (Scales are needed for use with the two quadrants.) The inscription in the cartouche below is written in a most unusual way, the space between the text being hatched with mainly diagonal strokes. The text reads:

sana’hu al-faqîr Muhammad Husayn ibn Muhammad Bâqir al-Yazdî sanata gh-n-z

that is, “Made by the (slave of God) needy (of his mercy) Muhammad Husayn ibn Muhammad Bâqir al-Yazdî in the year 1057 H [= 1647/48]”

The maker’s father, Muhammad Bâqir al-Yazdî, was the leading mathematician of Safavid Iran. Muhammad Husayn authored some works on instruments that survive but have not been studied yet.

Bibliography: On Muhammad Husayn see King, World-Maps, pp. 255-256, and also the entry under his name in the forthcoming Biographical Encyclopedia of Astronomers. On this astrolabe see Sotheby’s, London, 21 August 2000, lot 27, and more especially King, In Synchrony with the Heavens, II, pp. 1061-1063.

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