Al-Khazini

Abū al-Fath Abd al-Rahman Mansūr al-Khāzini or simply al-Khāzini (أبوالفتح عبدالرحمن منصور الخازنی (Persian), flourished 1115–1130) was an Iranian astronomer, mechanician and physicist of Byzantine Greek origin who lived during the Seljuk Empire. His astronomical tables, written under the patronage of Sultan Sanjar (Zīj al-Sanjarī, 1115), are considered to be one of the major works in mathematical astronomy of the medieval period.^: 107 He is considered to have been one of the greatest scientists of his era, among the greatest makers of scientific instruments of any time, and as "the physicist of all physicists".

Al-Khazini is one of the few Islamic astronomers to be known for doing original observations. He provided the positions of fixed stars, and for oblique ascensions and time-equations for the latitude of Marv in which he was based.^: 197 He also wrote extensively on various calendrical systems and on the various manipulations of the calendars. He also devised the world's most precise instrument for weighing ordinary objects, determining specific gravities, and even examining the composition of alloys. On the basis of his detailed description, it has been possible to reconstruct his complex mechanism, which he dubbed "The Comprehensive Balance". Modern study affirms his claim to its extraordinary accuracy of 1:60,000.

Al-Khazini was the author of an encyclopedia on scales and water-balances called The Book of the Balance of Wisdom (Kitab Mizan al-Hikmah, 1121), which explored theories of density, specific gravities of metals, precious stones, and liquids, as well as principles of equilibrium. The book is thought to have been "one of the most sophisticated and advanced balances to be designed and manufactured in the medieval Islamic world", and "the most comprehensive work on [weighing] in the Middle Ages, from any cultural area".