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This work, by Abu al-‛Abbās Ahmad b. Yūsuf al-Qaysī al-Tīfāshī, a 13th-century writer and mineralogist who was born in Tunisia and worked in Egypt, describes precious gems found in the treasuries of kings and rulers. The author lists 25 gemstones and dedicates a chapter to each. They include the ruby (*yāqūt*), emerald (*zumurrud*), topaz (*zabarjad*), diamond (*almās*), turquoise (*fīrūzaj*), magnetite (*maghnātīs*), agate (*‛aqīq*), lapis lazuli (*lāzward*), coral (*marjān*), and quartz (*talq*). In each chapter, the author discusses the causes of the gemstone’s formation, provenance, criteria for appraisal of ...

This work is a treatise for timekeepers (singular *muwaqqit*), and discusses the telling of time from such astronomical observations as the sun’s angle of inclination (*mayl*), altitude (*irtifā‛*), as well as the direction (*samt*) and length of cast shadows (*zill*). In 14 chapters, the author goes through methods for the computation of these factors, determination of the direction of prayer (*qibla*), and time of the day. He observes that using instruments (*ālāt*), such as markings on the ruler (*mistara*) and the compass (*bargār*, from the Persian *pargār*), and geometric ...

The author of this work, Ibn al-Majdī (1366-1447 [767-850 A.H.]), was a renowned mathematician, geometrician, and astronomer. He was linked with the influential Marāgha School through his teacher, Jamāl al-Dīn al-Māridīnī, who in turn had studied with Ibn al-Shātir al-Dimashqī’. As a descendant of a powerful local family with Mamlūk ties, Ibn al-Majdī served as the official astronomer and timekeeper at Al-Azhar. The work is divided into three chapters and a conclusion. Chapter 1 covers the procedure for projecting the circle of projection (*fadl al-dā’ir*) onto planes that ...

This manuscript is a didactic work on arithmetic and algebra, composed in versified form, as a *qasīda* of 59 verses. It was composed by Ibn al-Hā’im al-Fardī in 1402 (804 A.H.). The beginning of the work also names ‛Alī b. ‛Abd al-Samad al-Muqrī al-Mālikī (died Dhu al-Ḥijja 1381 [782 A.H.]), a scholar and teacher who had come to Egypt and taught at the ‛Amr b. ‛As madrasa for several years. The main part of the *qasīda* begins by introducing and defining key terms in arithmetic and algebra ...

This treatise, written on ten folio pages for an Ottoman official and patron of books known as Ismā‘īl Afandī, is on the inter-conversion of units of measurement. It is a useful guide for merchants and others engaged in the measurement of quantities. It provides instructions for converting *arṭāl* (plural of *raṭl*) into *uqaq* (plural of *auqiya*), and back; *darāhim* (plural of *dirham*) into *mathāqīl* (plural of *mithqāl*) and back; and converting the number of Ottoman (referred to as Roman, *rūmī*) loading bags into the number of Egyptian loading bags ...

This work is a tutorial text on elementary arithmetic, in 20 folios. It is divided into an introduction, 11 chapters, and a conclusion. In the beginning, the sign for zero is introduced, along with the nine Indian numerals, written in two alternative forms. This is followed by a presentation of the place system. The first four chapters cover, respectively, addition, subtraction, multiplication, and division. Chapter five introduces operations on non-whole numbers. The remaining six chapters discuss fractions and operations on them.

This work is a treatise on the important subject of timekeeping. It is a work of technical astronomy, in 19 folios, that begins by emphasizing the religious significance of knowledge of time. It is divided into an introduction, two chapters, and a conclusion. Comprehensive procedures for the construction of tables and their use are provided. The work was completed in 1473 (878 A.H.).

This work is a comprehensive tutorial guide on arithmetic and plane geometry, in 197 folio pages. It also discusses monetary conversion. The work is composed in verse form, and is meant as a commentary on existing textbooks. The author gives the following personal account of the writing of this guide: In Rajab 827 A.H. (May 1424) he traveled from Damascus to Quds al-Sharīf (in Palestine), where he met two scholars named Ismā‘īl ibn Sharaf and Zayn al-Dīn Māhir. There he took lessons on arithmetic, using an introductory book ...

This work, by a timekeeper at the Al-Azhar Mosque in Cairo, is an important and comprehensive textbook on timekeeping. It introduces the useful device of dividing a quarter of a circle of projection into sections known as *almucantars* (*muqanṭarāt*). The work, comprising 100 folio pages, contains 30 chapters and a conclusion. The work was composed in 1440-1 (844 A.H.) and was copied in 1757 (1170 A.H.).

This work is a noteworthy treatise on optics that covers such basic topics as direct vision, reflection and refraction, and the length of shadows. It discusses convex and concave mirrors and the physiology of vision, and has a section on optical illusions. It is a cogent work on geometrical optics. It is particularly significant because it was written under the Ottoman sulṭān, Murāt ibn Selīm (reigned 1574-95 [982-1003 A.H.]). The name of the author is illegible on the front page, and seems to have been deliberately wiped off for ...

This is a work on timekeeping and the determination of the direction of prayer (*qibla*), particularly intended for people who travel. The author, Abu al-‛Abbās Shihāb al-Dīn Ahmad b. Zayn al-Dīn Rajab b. Tubayghā al-Atābakī, known as al-Majdī or Ibn al-Majdī (1366-1447 [767-850 A.H.]), was descended from a powerful family with ties to Mamlūk rulers and was a renowned and prominent mathematician, geometrician, and astronomer. He served as the timekeeper of the Al-Azhar Mosque. This work is an abridgment of his other major book, *Irshād al-ḥā’ir ilā ...*

This work, a treatise on practical astronomy, deals with such issues as timekeeping and determining the proper direction of prayer. The work begins with a brief introduction, but the bulk of the manuscript contains tables used to determine time. The introductory section contains illustrative examples on how to use the tables.

This work on elementary knowledge of practical astronomy begins by emphasizing the religious significance of knowing how to keep the time and how to determine the proper direction of prayer (*qibla*). It describes the conventional correspondence between ordinal numbers and the letters of the Arabic alphabet. It then enumerates, and goes through, the names of the months in the lunar Arabic calendar and in the solar Coptic calendar. It highlights certain important dates, such as the beginning of the New Year, and introduces the 12 zodiacal signs. The front page ...

This manuscript is a work on practical astronomy and the drawing of the circle of projection and related concepts from spherical trigonometry. It is rich with geometric diagrams, tables of empirical observations, and computations based upon these observations. An interesting feature of the manuscript is the appearance on the margins of the cover, and on several pages in the manuscript, of edifying verses, proverbs, and witty remarks. One reads, for example, “It is strange to find in the world a jaundiced physician, a dim-eyed ophthalmologist, and a blind astronomer.” Most ...

This treatise deals specifically with basic arithmetic, as needed for computing the division of inheritance according to Islamic law. It contains 48 folios and is divided into an introduction, three chapters, and a conclusion. The introduction discusses the idea of numbers as an introduction to the science of arithmetic. Chapter I discusses the multiplication of integers. Chapter II is on the division of integers and the computation of common factors. Chapter III deals extensively with fractions and arithmetic operations on them. The author, an Egyptian jurist and mathematician, was the ...

This treatise contains information on a medley of subjects, including alchemy, numerology, mineralogy, and magic. It begins with quotations from *Kashf al-asrār wa hatk al-astār *(Unveiling of secrets and tearing of covers), a well-known eighth-century (second-century A.H.) work attributed to Jābir (ibn Ḥayyān). A whole other work seems to be written in the margins. The text mentions such authorities as Galen (Jālīnūs), Zīsmūs, Hermes, Democrates, Shaykh Abu al-‘Abbās Aḥmad al-Baunī, and Ghazālī. Parts of the manuscript are smudged and damaged.

The present work is a further commentary on the *ḥāshiyah* (gloss) by al-Sayyid al-Sharīf al-Jurjānī (died 816 AH [1413 AD]) on the *Lawāmi’ al-asrār* by Qutb al-Dīn al-Taḥtānī al-Rāzī (died 766 AH [1364 AD]). The latter is, in turn, a commentary on a book of logic entitled *Maṭāli’ al-anwār* by Sirāj al-Dīn Maḥmūd al-Urmawī (died 682 AH [1283 AD]). The scribe of this work, who may also have been the author, was Muhammad ibn Pir Ahmad al-Shahir bi-Ibn Arghun al-Shirazi. Written for the library of the Ottoman Sultan Selim I ...