As we saw in the last two articles, the Arabs were the world’s experts in astronomy during the Arab renaissance, between the tenth and fifteenth centuries. They left behind the hundreds of manuscripts about this science, as well as various astronomical instruments that were masterpieces of science and art.
The Center for Documentation of Culture and Natural Heritage had set a special exhibition called “Stargazers”, to highlight the contribution of Arab civilization to Astronomy.
The exhibition includes perfect replicas of astrolabes, sundials, water & sand clocks and celestial and terrestrial globes. There are eleven astrolabes, dating back to between the tenth and fourteenth centuries, with the originals exhibited in museums in countries like Germany, France, Italy, the United Kingdom and Turkey. The average diameter of the astrolabes is about 15 cm, but there’s even a pocket astrolabe, only 7cm in diameter.
There are three sundials, one being a replica of the one at Ibn-Tuloun Mosque in Cairo, the second a replica of the one at the Umayyad mosque in Damascus and the third the replica of a Latin sundial that was manufactured by an Arab called Mohamed Al-Tantawi.
One of the masterpieces in the exhibition is the replica of a water clock, installed on the outer wall of the Umayyad mosque and engineered by Mohamed Ben Ali Alsaati in the twelfth century. This clock, although burnt in a fire, was reconstructed for the exhibition using the description and sketches found in a manuscript written by the manufacturer.
The water clock, 2m long by 3m wide, contains a tank of water that has a regulating tap at the bottom and a float at the top. When the water flows, the float goes down; pulling a thread that activates a mechanism which in turn lets panels carrying twelve numbers fall down one after another with every hour of the day. Also with every hour, two small metal balls fall in a metal cup making two knocking sounds. That was really one of the first ticking clocks.
Another masterpiece in the exhibition is a terrestrial globe constructed according to information in a manuscript entitled “Masalik Al-Absar” written at the time of Caliph Al Ma’mun in the ninth century. Half of the globe id called the “Sea of Darkness” where the Americas were to be discovered 700 years later.
The exhibition also includes a multimedia presentation on a big screen that explains how the astrolabe works.
