Maragheh: an observatory with a library attached
In the thirteenth century, Nasir al-Din al-Tusi gathered astronomers, instruments and books on a hill in Azerbaijan.
The observatory at Maragheh was founded in 1259 under Ilkhanid patronage and directed by Nasir al-Din al-Tusi. It had large instruments, a staff of astronomers and a substantial library.1
The Persian name is Zij-i Ilkhani.
Tables that took twelve years
Its work produced the Ilkhanic Tables, completed around 1272. Al-Tusi also proposed a pairing of circles, now called the Tusi couple, that turns circular motion into straight-line motion.
- The mater is the body of the instrument: a heavy disc with a raised rim marked in degrees or hours.
- Inside sits a plate engraved for one latitude, with lines for the horizon and the heights above it.
- Over it turns the rete, an open star map. Turning it shows the sky at any hour.
- On the back, the alidade is a sighting rule. Aim it at the sun or a star to read its height.
Notes
- The Persian name is Zij-i Ilkhani. ↩