THE DRAGON WATER CLOCK A CLOCK FROM THE 12TH CENTURY AD.

Of the most outstanding master pieces of science and technology of Iran from old ages to the present are the water clocks by Abol ezz-Ibn Al-Jazzari. He lived in the 11th century AD. and his remaining works are proofs of his high levels of capability in different sciences such as mechanical engineering, fluid mechanics, robotics and mechanism design. Amongst his works, water pumps, pump turbines, water clocks, robotic clocks, and fountains are the most outstanding. Since these works were no research work nor any reconstruction or research activity has been performed on them, so the Iranian Research Organization for Science and Technology (IROST) through his mechanical engineering research center embarked upon their revitalization in the form of a research project. Of these master pieces of design and technology, two were selected as the main subjects of a work for a research project titled "Revitalization of innovations and inventions of the Iranian scientists through the history". These two were namely, Peacock Water Clock and Dragon Water Clock. As a part of this work, the two clocks were carefully redesigned and reconstructed, and both tested according to Al- Jazari's book on design and manufacture of his ingenious designs. The article consists of a short introduction of the scientist; Al- Jazari and then the details of designs, manufacture and testing of the clocks. The results of tests are discussed in brief.