A mechanical alarm clock was described by the Ottoman engineer Taqi al-Din in his book, The Brightest Stars for the Construction of Mechanical Clocks (Al-KawÃÂkib al-durriyya fë wadh' al-bankÃÂmat al-dawriyya), published in 1556-1559. It was capable of sounding at a specified time, achieved by placing a peg on the dial wheel. At the requested time, the peg activated a ringing device. In the same treatise, he described a mechanical astronomical clock called the "observational clock", which measured continuance in minutes. He fabricated applicability of his mathematical knowledge to design three dials which showed the hours, degrees and minutes. He later improved the doodle of his observational clock to amount era in seconds in an astronomical treatise written at his Istanbul observatory of al-Din (1577-1580). He described his observational clock as "a mechanical clock with three dials which show the hours, the minutes, and the seconds." This was an important innovation in 16th-century practical astronomy, as previous clocks were not accurate enough to be used for astronomical purposes. He further improved the observational clock, using only one dial to represent the hours, minutes and seconds, describing it as "a mechanical clock with a dial showing the hours, minutes and seconds and we divided every minute into five seconds."
The word clock is derived ultimately (via Dutch, Northern French, and Medieval Latin) from the Celtic words clagan and clocca meaning "bell". For horologists and other specialists the style clock continues to mean exclusively a device with a striking mechanism for announcing Time Clock intervals of time acoustically, by ringing a bell, a customary of chimes, or a gong. A silent instrument needed such a mechanism has traditionally been popular as a timepiece. In general usage today, however, a "clock" refers to any device for measuring and displaying the day which, unlike a watch, is not worn on the person.
