Actual homework question: What is the reason for the variety of colors that quartz exhibits?
quartz clock-Sheibe and Essen First water clock-Ctesibius
Quartz clock. According to the Smithsonian In 1927, Canadian-born Warren Marrison, a telecommunications engineer, was searching for reliable frequency standards at Bell Telephone Laboratories. Building on earlier work in piezoelectricity, he developed a very large, highly accurate clock based on the regular vibrations of a quartz crystal in an electrical circuit - the first quartz clock. Water Clocks Water clocks were among the earliest timekeepers that didn't depend on the observation of celestial bodies. One of the oldest was found in the tomb of the Egyptian pharaoh Amenhotep I, buried around 1500 BCE. Later named clepsydras (water thieves) by the Greeks, who began using them about 325 BCE, these were stone vessels with sloping sides that allowed water to drip at a nearly constant rate from a small hole near the bottom. More elaborate and impressive mechanized water clocks were developed between 100 BCE and 500 CE by Greek and Roman horologists and astronomers. In the Far East, mechanized astronomical/astrological clock making developed from 200 to 1300 CE. Third-century Chinese clepsydras drove various mechanisms that illustrated astronomical phenomena. One of the most elaborate clock towers was built by Su Sung and his associates in 1088 CE. Su Sung's mechanism incorporated a water-driven escapement invented about 725 CE. The Su Sung clock tower, over 30 feet tall, possessed a bronze power-driven armillary sphere for observations, an automatically rotating celestial globe, and five front panels with doors that permitted the viewing of changing manikins which rang bells or gongs, and held tablets indicating the hour or other special times of the day.
