Risālah fī al-burūj wa-al-manāzil : Farāʼid jawharīyah fī fawāʼid al-mīqātīyah

This work is an introductory, but well-organized, treatise on the elements of time-keeping and reckoning. The treatise is divided into seven sections and a conclusion. It introduces the Arabic, Coptic, and Syriac (or Alexandrian) calendars, and comments on the Persian, Roman, and Hebraic calendars. The work gives the names and lengths of the months in various calendars, explains the different methods for ascertaining the beginnings of years and months, discusses the signs of the zodiac and their relation to the four seasons, and describes the apparent motion of the sun and the moon, explaining the changing length of days and nights in the course of the seasons. The concluding section presents methods for the determination of the date, time, and the qibla (direction of prayer) in various geographical locations. Parts of the text have brief commentary in the margins. The text includes two tables and a diagram. The manuscript was completed on 28 Jumādā II 1247 AH (December 4, 1831). World Digital Library.