Taqī al-Dīn ibn Ma'rūf was a major Ottoman scientist who excelled in science in the second half of the 16th century. From 1571, he settled in Istanbul, the capital of the Ottoman Empire and excelled in several scientific fields such as mathematics, astronomy, engineering and mechanics, and optics. He was the author of several texts, some of which manuscripts survived and are at present the subject of thorough studies in the history of science. One of his books, Al-Turuq al-saniyya fi al-alat al-ruhaniyya (The Sublime Methods of Spiritual Machines), described the workings of a rudimentary steam engine and steam turbine, predating the more famous discovery of steam power by Giovanni Branca in 1629. Taqī al-Dīn is also known for the invention of a 'monobloc' six cylinder pump, for his construction of the Istanbul observatory, and for his astronomical activity there for several glorious years until the observatory was closed.
1. Biographical outline
Taqī al-Dīn Abū Bakr Muhammad ibn Qādhī Ma'rūf ibn Ahmad al-Shāmī al-'Asadī al-Rāsid (1526-1585), was an Ottoman astronomer originary from Damascus who worked in Istanbul. Known as al-Rāsid (the observer) because of his fame as astronomer and especially as observer and head of the known Istanbul observatory, he excelled also in other scientific branches, from mathematics and optics to mechanics and engineering.
Taqī al-Dīn was born in Damascus in 1526. He worked for a time as a judge and teacher at Nablus (in Palestine), Damascus and Cairo. During his stay in Egypt and Damascus, he produced some important works in the fields of astronomy and mathematics. In 1570, he came to Istanbul from Cairo, and one year later (1571-2) was appointed chief astronomer (Munajjimbashi) upon the death of Chief Astronomer Mustafa b. Ali al-Muwaqqit . Taqī al-Dīn maintained close relations with many important members of the ulema and statesmen, chief among whom was Hoca Sadeddin, and was presented to Sultan Murad by the Grand Vizier Sokullu Mehmed Pasha .
2. Istanbul observatory
Taqī al-Dīn informed Sultan Murād, who had an interest in astronomy and astrology that the Ulug Bey Astronomical Tables contained certain observational errors, resulting in errors in calculations made on the basis of those tables. Taqī al-Dīn indicated that these errors could be corrected if new observations were made and proposed that an observatory be built in Istanbul for that purpose. Sultan Murād was very pleased to be the patron of the first observatory in Istanbul and asked that construction began immediately. He also provided all the financial assistance required for the project. In the meantime, Taqī al-Dīn pursued his studies at the Galata Tower, which he continued in 1577 at the partially completed new observatory that he called Dār al-Rasad al-Jadīd (the New Observatory). He founded the first observatory in Istanbul during the reign of Ottoman Sultan Murad III (1574-1595) which housed a library, comprising mainly books on astronomy and mathematics.
The observatory, consisting of two separate buildings, one large and one small, was constructed at a location in the higher part of Tophane in Istanbul. Taqī al-Dīn had the instruments used in the old Islamic observatories reproduced with great care. In addition, he invented some new instruments which were used for observational purposes for the first time. The observatory had a staff of sixteen people-eight "observers" (rāsid), four clerks, and four assistants.
The observatory was designed to provide for the needs of the astronomers and included a library and certainly a workshop for the design and the production of instruments. This institution was conceived as one of the largest observatories in the Islamic world and was completed in 1579. It was comparable to Tycho Brahe's (1546-1601) Uranienborg observatory built in 1576. There is a striking similarity between the instruments of Tycho Brahe and those of Taqī al-Dīn. In his astronomical tables, called the Sidratu Muntaha 'l-afkār fī malakut al-falak al-dawwār (Culmination of Thoughts in the Kingdom of Rotating Spheres), Taqī al-Dīn states that he started activities on astronomy in Istanbul with 15 assistants in 1573. The observatory continued to function until 22 January 1580, the date of its destruction. Religious arguments were put forth to justify this action, but it was really rooted in certain political conflicts .
3. Astronomical instruments of the observatory
The followings instruments were among those used in the observatory to perform observations:
- 1) An armillary sphere;
- 2) A mural quadrant;
- 3) An azimuthal quadrant;
- 4) A parallel ruler;
- 5) A ruler-quadrant or wooden quadrant;
- 6) An instrument with two holes for the measurement of apparent diameters of heavenly bodies and eclipses;
- 7) An instrument with chords to determine the equinoxes, invented by Taqī al-Dīn to replace the equinoxial armillary;
- 8) A mushabbaha bi'l-manātiq, another instrument of his invention, the nature and function of which is not yet explained;
- 9) A mechanical clock with a train of cogwheels;
- 10) A sunaydi ruler, apparently a special type of instrument of an auxiliary nature, the function of which was explained by Alauddin al-Mansur.
Taqī al-Dīn invented new observational instruments that were added to the array of those already in use for observation in the Islamic world. Among the instruments invented by Taqī al-Dīn in the observatory were the following:
- The Sextant (mushabbaha bi-'l manātiq): used to measure the distances between the stars. Taqī al-Dīn's mushabbaha bi'l manātiq and Tycho Brahe's sextant should be considered among the great achievements of the 16th century astronomy. A mushabbaha bi-l manātiq is composed of three rulers. Two of them are attached as the rulers of triquetrum. An arc is attached to the end of one of the rulers. Taqī al-Dīn made this instrument to observe the radius of Venus that was mentioned in the tenth book of Ptolemy's Almagest [6].
- The Dhāt al-awtar: designates the spring and autumn equinoxes. Some astronomers set up a ring, which was not divided, parallel to the equator to designate this. Taqī al-Dīn invented his instrument in the new observatory. The instrument was composed of a base in the form of a rectangle and four columns. The two columns were set on the base so that a string was stretched between them. One of them was equal to the cosine of the latitude of the country and the other to the sine. A hole was made on each of these parts according to this proportion. A rope was hung from these holes with a plumb.
- The astronomical clock: Taqī al-Dīn used a mechanical clock, which he made himself for his observations, and a wooden wall dial, which he set up in the observatory. This clock was more precise than those previously used and considered to be one of the most significant inventions in the field of applied astronomy in the 16th century. It is described as folows in The Astronomical Instruments for the Emperor's Table: "The ninth instrument is an astronomical clock. The following statement is recorded from Ptolemy: ‘I would have been able to establish a great regularity in method if I was able to measure the time precisely'. Now Taqī al-Dīn planned, with the help of God, the astronomical clock by the command of the Sultan, God perpetuates his ruling days. Thus, he was able to do what Ptolemy had failed to do". In addition, in Sidrat al-muntaha, Taqī al-Dīn said: "we built a mechanical clock with a dial showing the hours, minutes and seconds and we divided every minute into five seconds ."
When we compare the instruments that Taqī al-Dīn used in his observatory with those used by Tycho Brahe, they are mostly similar, but some of Taqī al-Dīn's are larger and more precise. For example, they both used a mural quadrant (libna) for the observation of the declinations of the sun and the stars. It is said that Taqī al-Dīn preferred a mural quadrant instead of the sudus al-fakhrī and two rings used by the previous astronomers. Taqī al-Dīn's quadrant was formed of two brass quadrants with a radius of six metres each, placed on a wall and erected on the meridian. The same instrument used by Brahe was only two meters in diameter .
In his observational work, Taqī al-Dīn integrated the Damascus and Samarkand traditions of astronomy. His first task at the observatory was to undertake the corrections of the Ulug Bey Astronomical Tables. He also undertook various observations of eclipses of the sun and the moon. In September 1578, a comet appeared in the skies of Istanbul for one month; the staff of the observatory set to observe it ceaselessly day and night and the results of the observations were presented to the sultan. Taqī al-Dīn was, as a result of the new methods he developed and the equipment he invented, able to approach his observations in an innovative way and produce novel solutions to astronomical problems. He also substituted the use of a decimally based system for a sexagesimal system and prepared trigonometric tables based on decimal fractions. He determined the ecliptic degree as 23º 28' 40', which is very close to the current value of 23º 27'. He used a new method in calculating solar parameters. In particular, he determined that the magnitude of the annual movement of the sun's apogee was 63'. Considering that the value known today is 61', the method he used appears to have been more precise than that of Copernicus (24 seconds) and Tycho Brahe (45 seconds).
The observatory was witness to a great deal of activity within a short period of time between 1577 and 1580 . Observations undertaken there were collected in a work titled Sidrat Muntahā'l-Afkār fī Malakūt al-Falak al-Dawwār. When compared with those of the contemporary Danish astronomer Tycho Brahe, Taqī al-Dīn's observations are more precise. Furthermore, some of the instruments that he had in his observatory were of superior quality to Tycho Brahe's
Dr. Salim Ayduz
