[Tercüme-i Kedusî li’l Mukantarat – İlâveli Tercüme-i Kedûsî li’l Ceyb / Translation of the Use of the Almucantar Quarter together with Translation of the Use a Quadrant / Ceyb]
An illustrated work in Ottoman language explains the use of two types of quadrants in astronomy and for religious purposes. The work was translated from the Arabic and edited by an Ottoman astronomer Gedusî Süleyman Murad Efendi (died 1854 (1270 H.)).
The book is divided into two parts, the first explaining the use of the almucantar quarter, basic numeric values of Arabic letters and astronomy.
The second part is dedicated to the ceyb, again a type of a quadrant. The word, coming from Arabic jiba (جيب), meaning the pocket (Ottoman and Turkish cep), also started to mark a curved line, and eventually a curved line – sinus -in the mathematics. The word sinus, which we still use today, was translated from Arabic to Latin in the 12th century.
This second part also includes charts of the sunrise and sunset.
The Islamic Quadrant
An Islamic quadrant, also called a “computer of the Ottoman Empire”, is a scientific instrument with two sides, which determines the prayer times, the sun elevation angle, the projection line of a certain latitude. It also calculates spherical trigonometric functions, and position of the celestial objects.
A quadrant is one of the oldest astronomical instruments. It is recorded from the 2nd centuy on and was widely used in the Islamic world in the 16th and 17th centuries, usually made of hardwood, such as boxwood. The use of the quadrant fell out of fashion in the first half of the 19th century during so called Tanzimat Reforms, which lasted from 1839 to 1876, when the ancient knowledge in Ottoman schools was revoked by the Europeanisation of the system, started by Mustafa Reşid Pasha (1800 – 1858).
References: Türkischer Biographischer Index, 2011, pp. 134, 288