Two books published in 2004-05

•      In Synchrony with the Heavens: Studies in Astronomical Timekeeping and Instrumentation in Medieval Islamic Civilization, vol. 1: The Call of the Muezzin (Studies I-IX), Leiden: Brill Academic Publishers, 2004, ca. 1050 pages.

This first volume deals with astronomical timekeeping by the sun and stars and the regulation of the astronomically-defined times of Muslim prayer for over a millennium. It is based on over 500 Arabic manuscripts unearthed by the author in libraries around the world that had never been studied before. The earliest sources are from 8th- and 9th-century Baghdad, the later ones from all over the Islamic world.

I: A survey of tables for timekeeping by the sun and stars; II: A survey of tables for regulating the times of prayer; III: A survey of arithmetical shadow-schemes for time-reckoning; IV: On the times of prayer in Islam; V: On the role of the muezzin and the muwaqqit in medieval Islamic societies; VIa: Universal solutions in Islamic astronomy; VIb: Universal solutions from Mamluk Syria and Egypt; VIIa: On the orientation of medieval Islamic architecture and cities; VIIb: Architecture and astronomy: The ventilators of medieval Cairo and their secrets; VIIc: Safavid world-maps centred on Mecca; VIII: Aspects of practical astronomy in mosques and monasteries; IX: When the night sky over Qandahar was lit only by stars ... ... .

•      In Synchrony with the Heavens: Studies in Astronomical Timekeeping and Instrumentation in Medieval Islamic Civilization, Vol. 2: Instruments of Mass Calculation (Studies X-XVIII), Leiden: Brill Academic Publishers, 2005, ca. 1150 pages.

This second volume deals with the astronomical instruments used by Muslim astronomers for over a millennium, most of which have not been published previously. It includes the first detailed descriptions of all of the instruments from 8th-, 9th and 10th-century Baghdad, and much new information based on several hundred instruments preserved in museums and private collections around the world.

X: Astronomical instrumentation in the Islamic world; XI: An approximate formula for timekeeping (750-1900); XIIa: On the universal horary quadrant for timekeeping by the sun; XIIb: On universal horary dials for timekeeping by the sun and stars; XIII: Selected early Islamic astrolabes; XIIIa: The neglected astrolabe – A supplement to the standard literature on the favourite astronomical instrument of the Middle Ages; XIIIb: The oldest astrolabe in the world, from 8th-century Baghdad; XIIIc: Astrolabes from late-9th- and 10th-century Baghdad; XIIId: A medieval Italian testimonial to a forgotten Islamic tradition of non-standard astrolabes; XIIIe: The origin of the astrolabe according to medieval Islamic sources; XIV: Selected late Islamic astrolabes; XIVa: An astrolabe made by the Yemeni Sultan al-Ashraf; XIVb: Some astronomical instruments from medieval Syria; XIVc: A monumental astrolabe from 13th-century Damascus; XIVd: An astrolabe for the Sultan Ulugh Beg; XIVe: Two astrolabes for the Ottoman Sultan Bayazid II; XIVf: Brief remarks on astronomical instruments from Muslim India; XIVg: A universal astrolabe from 17th-century Lahore ; XV: An astrolabe from medieval Spain with inscriptions in Hebrew, Arabic and Latin; XVI: The geographical data on early medieval Islamic instruments; XVII: The quatrefoil as decoration on astrolabe retes; XVIII: A checklist of Islamic astronomical instruments to ca. 1500, ordered chronologically by region.