Taqi ad-Din Muhammad ibn Ma'ruf ash-Shami al-Asadi (1526–1585) was an Ottoman expert in many fields who lived and worked in Cairo and Istanbul. He wrote more than ninety books on subjects such as astronomy, clocks, engineering, mathematics, mechanics, optics, and natural philosophy.

In 1574, the Ottoman Sultan Murad III asked Taqi ad-Din to build an observatory in Istanbul. He created tools like an armillary sphere and mechanical clocks to study the Great Comet of 1577. He also used European celestial and terrestrial globes that were given as gifts to Istanbul.

His most important work from the observatory is called "The Tree of Ultimate Knowledge in the Kingdom of the Revolving Spheres: The Astronomical Tables of the King of Kings [Murad III]." This work was based on observations made in Egypt and Istanbul to improve and complete Ulugh Beg’s 15th-century book, the Zij-i Sultani. The first 40 pages explained calculations, followed by descriptions of astronomical clocks, heavenly circles, and details about three eclipses he observed in Cairo and Istanbul.

As an expert in many areas, Taqi ad-Din wrote books on astronomy, mathematics, mechanics, and theology. His method for finding star coordinates was so accurate that his measurements were better than those of his contemporaries, Tycho Brahe and Nicolas Copernicus. Brahe is believed to have known about Taqi ad-Din’s work.

Taqi ad-Din also described a steam turbine that could rotate a spit in 1551. He built astronomical clocks for his observatory and wrote a book on optics. In this book, he explained how light comes from objects, proved the Law of Reflection through experiments, and studied refraction.

Biography

Taqī al-Dīn was born in Damascus in 1526, according to most sources. His background has been described as Arab, Kurdish, Syrian, and Turkish. In his book, titled "Rayḥānat al-rūḥ," Taqī al-Dīn claimed his family was related to the Ayyubids, a group of rulers from the 12th century in Syria. The Encyclopaedia of Islam does not mention his background, only calling him "the most important astronomer of Ottoman Turkey."

Taqī al-Dīn’s education began with studying religion. Later, he became interested in subjects like math and science. He studied these subjects in Damascus and Cairo, alongside his father, Maʿruf Efendi. He later taught at several schools and worked as a judge in Palestine, Damascus, and Cairo. He stayed in Egypt and Damascus for a time, where he did important work in astronomy and mathematics. In 1571, he became the chief astronomer to the Sultan, replacing Mustafa ibn Ali al-Muwaqqit after moving to Istanbul.

Taqī al-Dīn had close connections with religious scholars and government officials. He shared information with Sultan Murad III, who was interested in astronomy and astrology. He told the Sultan that the Ulugh Beg Zij, a set of astronomical records, had errors. He suggested these errors could be fixed with new observations and proposed building an observatory in Istanbul. Murad III supported the idea and provided money for the project.

While this was happening, Taqī al-Dīn continued his studies at the Galata Tower. He studied there until 1577, when the observatory, called Dar al-Rasad al-Jadid, was nearly finished. The observatory had a library with books on astronomy and math. It was built in Tophane, Istanbul, and had two buildings: one large and one small. Taqī al-Dīn used instruments from older Islamic observatories, made copies of them, and created new ones for observations. The observatory had sixteen staff members, including eight observers, four clerks, and four assistants.

Taqī al-Dīn used creative methods and new tools to solve astronomical problems. He created trigonometric tables using decimal numbers. His calculations placed the ecliptic at 23° 28' 40", while the current value is 23° 27'. His measurements of the sun’s movement were also more precise than those of Copernicus and Tycho Brahe.

The observatory’s main goal was to help astronomers by providing a library and workshop for making instruments. It became one of the largest observatories in the Islamic world. Completed in 1579, it operated until January 22, 1580, when it was destroyed. Some believe religious disagreements caused the destruction, but political issues were the real reason. A report by Grand Vizier Sinan Pasha explained that the Sultan and Vizier tried to keep Taqī al-Dīn away from religious scholars to avoid accusations of heresy.

Although Taqī al-Dīn was original in his work, his influence was limited. Few copies of his writings survived, so they did not reach many people. However, one of his works and a library he owned reached Western Europe quickly. Dutch professor Jacob Golius, who studied Arabic and math, collected manuscripts in Istanbul. In 1629, Golius wrote to Constantijn Huygens about seeing Taqī al-Dīn’s work on optics in Istanbul. Later, this work was placed in the Bodleian Library, showing Golius successfully acquired it.

According to Salomon Schweigger, a chaplain for the Habsburg ambassador, Taqī al-Dīn was a charlatan who tricked Sultan Murad III into spending large amounts of money.

Taqī al-Dīn died at age 59 in 1585, after writing more than ninety books.

The Constantinople Observatory

Taqī al-Dīn was the founder and director of the Constantinople Observatory, also known as the Istanbul Observatory. This observatory is often called one of Taqī al-Dīn's most important contributions to astronomy in the 16th century. It is considered one of the largest observatories in Islamic history. It is frequently compared to Tycho Brahe's Uraniborg Observatory, which was known for having the best instruments in Europe at the time. Taqī al-Dīn and Brahe are often compared for their work in astronomy during the 16th century. The observatory was started in 1570 when Taqī al-Dīn returned to Istanbul after spending 20 years in Egypt studying astronomy and mathematics. Shortly after his return, Sultan Selīm II appointed Taqī al-Dīn as the head astronomer (Müneccimbaşı) following the death of the previous head astronomer, Muṣṭafā ibn Alī al-Muwaqqit, in 1571.

During his early years as head astronomer, Taqī al-Dīn worked in the Galata Tower and a building near Tophane. His work helped him gain the support of important Turkish officials. These relationships led to an imperial order in 1569 from Sultan Murad III to build the Constantinople Observatory. The observatory housed many books and instruments, had sixteen assistants who helped make scientific tools, and included many respected scholars of the time. While details about the building’s design are unclear, many drawings show the scholars and instruments used there. It was from this observatory that Taqī al-Dīn discovered the Great Comet of 1577. Sultan Murad III saw the comet as a bad sign for a war with the Safavids and also blamed Taqī al-Dīn for a plague happening at the time. Due to political problems, the observatory was closed in 1579 and completely destroyed by the state on January 22, 1580, just 11 years after it was built.

The success and failure of Taqī al-Dīn and his observatory were influenced by political events. Because his father was a professor at a law school in Syria, Taqī al-Dīn spent much of his life in Syria and Egypt. During his trips to Istanbul, he connected with important scholars and used the private library of the Grand Vizier, Semiz Ali Pasha. He later worked under the private mentor of Sultan Murad III, Sokollu. While in Egypt, Taqī al-Dīn continued his research on the stars using the Galata Tower and Sokollu’s home. Although Sultan Murad III ordered the observatory to be built, Sokollu had the idea after learning about the sultan’s interest in science. The sultan provided Taqī al-Dīn with financial and intellectual support, including access to books and resources. Murad III saw the observatory as a way to show the power of his monarchy, not only by funding it but also by uniting top astronomers to work together. He ensured records of the observatory’s work were kept by his court historian, Seyyid Lokman, who claimed the sultan’s power was greater than that of rulers in Iraq, Persia, and Anatolia. Lokman also said Murad III was superior to other kings because the observatory’s discoveries were new and replaced older knowledge.

Taqī al-Dīn used many instruments to help with his work. Some were already used by European astronomers, while others were inventions of his own. He not only used existing tools but also created new ones. One of his most important inventions was an automatic mechanical clock.

• Instruments described by Ptolemy: An Armillary Sphere (a model of the sky with rings showing longitude and latitude), a Paralactic Ruler (or Triquetrum, used to measure the height of stars), and an Astrolabe (used to find the position of celestial objects).
• Instruments created by Muslim astronomers: A Mural Quadrant (a device for measuring angles up to 90 degrees) and an Azimuthal Quadrant.
• Instruments created by Taqī al-Dīn: A Parallel Ruler, a Ruler Quadrant (or Wooden Quadrant, used to measure the size of objects and eclipses), a mechanical clock with gears to track the movement of stars, and the Muşabbaha bi'l-menatık (a tool with strings to determine the equinoxes, replacing the equinoctial armillary).
• A Sunaydi Ruler, a special tool whose purpose was explained by Alaeddin el-Mansur.

Contributions

Before the sixteenth century, European mechanical clocks were not widely used. This was because they were very expensive and not accurate enough for people who needed to know when to pray. People used hourglasses, water clocks, and sundials, which met their needs well.

Around 1547, the Ottomans began to want mechanical clocks more. This started when the Austrians gave gifts that included clocks. This created a market for clocks in the Ottoman Empire. European clockmakers made clocks that matched the tastes and needs of the Ottoman people. These clocks showed the phases of the moon and used Ottoman numbers.

Because of the high demand for mechanical clocks, Taqī al-Dīn was asked by the Grand Vizier to build a clock that could show the exact time for the call to prayer. This led him to write his first book on building mechanical clocks, called al-Kawakib al-Durriya fi Bengamat al-Dawriyya (The Brightest Stars for the Construction of Mechanical Clocks), in 1563 A.D. He used this book during his research at an observatory. He believed that understanding the movement of the stars and planets would help improve clock design. To learn more about how clocks worked, Taqī al-Dīn studied with European clockmakers and examined many clocks in the treasury of Semiz Ali Pasha.

In the Grand Vizier’s treasury, Taqī al-Dīn studied three types of clocks: weight-driven, spring-driven, and lever escapement-driven. He wrote about these and also mentioned pocket watches and astronomical clocks. As Chief Astronomer, he built a mechanical astronomical clock. This clock allowed more precise measurements at the Constantinople observatory. This invention was considered one of the most important astronomical discoveries of the sixteenth century. Taqī al-Dīn created a mechanical clock with three dials that showed hours, minutes, and seconds. Each minute in his clock was divided into five seconds. After this, it is not known if his work on clocks continued, as European clockmakers later took over much of the clockmaking in the Ottoman Empire.

In 1551, Taqī al-Dīn described a self-rotating spit, which is important in the history of the steam turbine. In Al-Turuq al-samiyya fi al-alat al-ruhaniyya (The Sublime Methods of Spiritual Machines), he explained this machine and its practical uses. The spit rotated when steam was directed into vanes, which turned a wheel at the end of an axle. He also described four water-raising machines. The first two were animal-powered water pumps. The third and fourth used a paddle wheel. The third was a slot-rod pump, and the fourth was a six-cylinder pump. The final machine used vertical pistons operated by cams and trip-hammers, which were powered by the paddle wheel. These descriptions came before many modern engines. For example, the screw pump Taqī al-Dīn described was made before Agricola’s description of the rag and chain pump in 1556. The two-pump engine he described was also the basis for the steam engine, which was first described by al-Jazarī.

Important works

• Sidrat muntahā al-afkār fī malakūt al-falak al-dawwār (al-Zīj al-Shāhinshāhī): This is considered one of Taqī al-Dīn's most important works in astronomy. He wrote this book based on his observations in Egypt and Istanbul. The goal of this work was to improve, correct, and finish the Zīj-i Ulugh Beg, a project started in Samarkand and continued in the Constantinople Observatory. The first 40 pages of his writing explain trigonometric calculations, including functions like sine, cosine, tangent, and cotangent.
• Jarīdat al-durar wa kharīdat al-fikar is a zīj that is said to be Taqī al-Dīn's second most important work in astronomy. This work includes the first recorded use of decimal fractions in trigonometric functions. He also calculated the parts of degrees for curves and angles using decimal fractions with precise measurements.
• Dustūr al-tarjīḥ li-qawā id al-tasṭīḥ is another important work by Taqī al-Dīn. It focuses on how to project a sphere onto a flat surface, as well as other geometric topics.
• Taqī al-Dīn is also credited with writing Rayḥānat al-rūḥ fī rasm al-sā āt alā mustawī al-suṭūḥ. This work discusses sundials and their features drawn on a marble surface.

• al-Kawākib al-durriyya fī waḍ al-bankāmāt al-dawriyya was written by Taqī al-Dīn in 1559. It addresses mechanical-automatic clocks. This work is considered the first written description of mechanical-automatic clocks in the Islamic and Ottoman world. In this book, he acknowledges Alī Pasha for allowing him to study his private collection of European mechanical clocks.
• al-Ṭuruq al-saniyya fī al-ālāt al-rūḥāniyya is a second book on mechanics by Taqī al-Dīn. It emphasizes the geometric and mechanical structure of clocks, a topic previously studied by Banū Mūsā and Ismail al-Jazari (Abū al-Izz al-Jazarī).

• Nawr ḥadīqat al-abṣar wa-nūr ḥaqīqat al-Anẓar was a work by Taqī al-Dīn that discusses physics and optics. This book explains the structure of light, the connection between light and color, as well as diffusion and global refraction.