Abū Sahl Wayjan ibn Rustam al-Qūhī (sometimes al-Kūhī), was a Persian[1]mathematician, physicist and astronomer. Quhi was from Kuh (or Quh), an area in Tabaristan, and flourished in Baghdad in the 10th century. He is considered one of the greatest Muslim geometers.
Many mathematical and astronomical writings are ascribed to him. He was the leader of the astronomers working in 988 AD at the observatory built by the BuwayhidSharaf al-Dawla. He devoted his attention to those Archimedean and Apollonian problems leading to equations higher than the second degree. He solved some of them and discussed the conditions of solvability.
In physics, al-Quhi discovered that the heaviness of bodies vary with their distance from the center of the Earth.[2]
^ Professor Mohammed Abattouy (2002), "The Arabic Science of weights: A Report on an Ongoing Research Project", The Bulletin of the Royal Institute for Inter-Faith Studies4, p. 109-130:
"For their parts, al-Quhi and Ibn al-Haytham had the priority in formulating the hypothesis that the heaviness of bodies vary with their distance from a specific point, the center of the earth."
References
Rashed, Roshdi (1996). Les Mathématiques Infinitésimales du IXe au XIe Siècle 1: Fondateurs et commentateurs: Banū Mūsā, Ibn Qurra, Ibn Sīnān, al-Khāzin, al-Qūhī, Ibn al-Samḥ, Ibn Hūd. Reviews: Seyyed Hossein Nasr (1998) in Isis89 (1) pp. 112-113; Charles Burnett (1998) in Bulletin of the School of Oriental and African Studies, University of London61 (2) p. 406.
M. Steinschnieder, Lettere intorno ad Alcuhi a D. Bald. Boncompagni (Roma, 1863)
Suter, Die Mathematiker und Astronomen der Araber (75-76, 1900).
