Features October 23, 2002 Su Sung water clock tower use water clocks around 375 BCE. The Greek name for water clock was clepsydras, translated as “water thieves.” The Greeks varied this technology, using large bronze bowls with a tiny hole in the bottom. The sides of the bowl would be marked in the same way as the Egyptian version, but the bronze bow! would float in a large tub of water, and water would seep steadily into the bowl, reaching markers as time passed. Around the year 100 BCE, a Macedonian astronomer named Andronikos was a key player in bringing about the construction of a horologion (device for keeping time) in Athens, which is known today as the “Tower of Winds.” The eight-sided tower features 24-hour mechanized clepsydra and indicators for the eight winds, from which the tower is named. In China mechanized development of clocks occurred between 200 and 1300 BCE. One of the most intricate clock towers was built by Su Sung in 1088 CE. The tower stood over 30-feet tall had a water-driven sundial and celestial sphere for observation, and five paneled doors for observing manikins, which rang gongs, and held tablets announcing the hour and other special times of the day. Technological advancement of clocks slowed down in the Middle Ages in Europe. By the first half of the 14th century, large weight-driven clocks began to appear in the tow- ers of larger cities. Similar to water flow, these weight-driven clocks were difficult to reg- ulate and lost time easily. By the early 1500s, Peter Henlein, from Nuremburg, had invented spring-powered clocks. Smaller watches began to appear, and were popular among wealthier citizens. The clocks time-keeping ability slowed as the spring unwound, but these new devices were far more accurate than previous time inventions. In 1656, a Dutch scientist, Christiaan Huygens, had made the first pendulum clock ( though Galileo Gallilei had experimented with pendulums and had sketched out plans for a pendulum clock, he was unable to construct one before his death in 1642). Huygens first pendulum clock had an error of less than one hour each day. Later ver- sions could keep time within ten seconds of error per day; by the 1720s the pendulum clock’s accuracy had been increased to an error of about one second per day. Pendulum clocks were beginning to be replaced by quartz clocks in the 1920s: it was found that by placing an electric charge to a crystal, it would bend and change its shape; then if the same crystal was put under pressure it would generate an electric field, cre- © page 18 ating an electric frequency consistent enough to operate an electric clock display. Scientists have known for a long time that different elements have a particular res nance: that is, elements absorb and emit electromagnetic energy unique to the eleme As far as is known an atom of oxygen or hydrogen, or any element, is exactly the sa today as it was a million years ago. By tapping the resonance of different elements, sc entists were able to keep time. The first “atomic clock” was based on ammonia, but accuracy wasn't much of an improvement over existing clocks. It was found that cesiu was much better, and the latest records set by the cesium atomic clock claim to be ab to keep time within 30-billionths of a second per year. World time scales In 1852, the Greenwich Observatory began transmitting a standard time. T became known as Greenwich Mean Time (GMT), and acted as a world standard wi the expansion of the British Empire. Previous to this standard, most cities operated o a local time system, as the sun rises and falls at different times in almost every city i the world. After the invention of atomic clocks in the US, pressures were applied develop a new international standard. In January 1, 1972, the new Coordinat Universal Time (UTC) became recognized internationally. Although, it’s a US site, it possible to view time according to an atomic clock on the internet; visit the followi URL: . Global time zones are measured according to longitudinal grid-lines, which run nor to south through the planets poles. The prime meridian, which runs throu Greenwich, England, was agreed to be the prime meridian in 1884. Given the globe h 360 degrees of rotation, and 24 hours of time in a day, each of the globe's time zones approximately 15 degrees wide. The time zones are not exact because different popul tions of different regions have manipulated the zones for convenience. Daylight-Savings Time? The simple explanation is that daylight-savings time was developed to make bet use of sunlight. It saves energy except for the darkest months of the year. It also offe people the opportunity to enjoy more daylight activities in the evenings during summer months. There are some complaints about Daylight Savings time. People complain about ha ing to adjust their schedules and change their clocks. Farmers complain the loude: arguing that twice a year, for several weeks following the time change, chickens t time adjusting to the new routine. In 1947 Robertson Davies, in his work The Diary Samuel Marchbanks, wrote: “I don’t really care how time is reckoned so long as there some agreement about it, but I object to being told that I am saving daylight when reason tells me that I am doing nothing of the kind. I even object to the implicati that I am wasting something valuable if I stay in bed after the sun has risen. As admirer of moonlight I resent the bossy insistence of those who want to reduce my ti for enjoying it. At the back of the Daylight Savings scheme I detect the bony, blue-fi gered hand of Puritanism, eager to push people into bed earlier, and get them up ear er, to make them healthy, wealthy and wise in spite of themselves.” Benjamin Franklin has been credited with pioneering the idea of daylight-savings his essay, “A Economical Project.” The idea intrigued various people in Europe and w first advocated seriously by a London builder, William Willett, who wrote in brochure: “Everyone appreciates the long, light evenings. Everyone laments their sho age as autumn approaches; and everyone has given utterance to regret that the cle bright light of an early morning during spring and summer months is so seldom se or used.” As a builder Willett was usually up early, and was surprised to see how m houses were still shuttered after the sun had risen. Although Willett spent a fortune time and money lobbying British parliament to pass a daylight-savings bill, by the ti of his death in 1915 the bill had not been passed. The first country to legislate dayli savings was Germany on May 17, 1916. Britain followed suit on May 21, 1916. T early days were confusing for a lot of people, and raised much opposition from far ers. After the First World War, legislation in England was put in place that marked beginning of summer as the third Sunday in April, and then summer would end on first Saturday in October. The energy benefits became apparent during the Seco World War, when the clocks in England during the summer months were set two ho ahead of the GMT and remained one hour ahead of the GMT in winter. Today in m countries in the EEC, daylight-saving begins at 1a.m. on the last Sunday of March, ends at 1 a.m. on the last Sunday of October. In the US, daylight-saving begins at 2 a.m. on the first Sunday of April, and ends at a.m. on the last Sunday of October. Canada, along with most of North American offshore American interests, observes the same dates as the US. This year, in Cana Daylight Savings began 2 a.m. April 7 and ends 2 a.m. October 27.