to write his first book on the construction of mechanical clocks called, "al-Kawakib al-Durriya fi Bengamat al-Dawriyya" in 1563 A.D. which he used throughout his research at the short-lived observatory. He believed that it would be advantageous to bring a "true hermetic and distilled perception of the motion of the heavenly bodies." In order to get a better understanding of how clocks ran Taqī al-Dīn took the time to gain knowledge from many European clock makers as well as going into the treasury of Semiz Ali Pasha and learning anything he could from the many clocks he owned. Types of clocks examined Of the clocks in the Grand Vizier's treasury Taqī al-Dīn examined three different types. Those three were weight-driven, spring-driven, and driven by lever escapement. He wrote of these three types of watches but also made comments on pocket watches and astronomical ones. As Chief Astronomer, Taqī al-Dīn created a mechanical astronomical clock. This clock was made to permit more precise measurements at the Constantinople observatory. As stated above the creation of this clock was thought to be one of the most important astronomical discoveries of the sixteenth century. Taqī al-Dīn constructed a mechanical clock with three dials which show the hours, minutes, and seconds, with each minute consisting of five seconds. After this clock it is not known whether Taqī al-Dīn's work in mechanical clocks was ever continued, given that much of the clockmaking after that time in the Ottoman Empire was taken over by Europeans. Steam In 1551 Taqī al-Dīn described a self-rotating spit that 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) al-Dīn describes this machine as well as some practical applications for it. The spit is rotated by directing steam into the vanes which then turns the wheel at the end of the axle. Al-Dīn also described four water-raising machines. The first two are animal driven water pumps. The third and fourth are both driven by a paddle wheel. The third is a slot-rod pump while the fourth is a six-cylinder pump. The vertical pistons of the final machine are operated by cams and trip-hammers, run by the paddle wheel. The descriptions of these machines predates many of the more modern engines. The screw pump, for example, that al-Dīn describes predates Agricola, whose description of the rag and chain pump was published