The jeweler would display a clock in his window, which was periodically adjusted to solar noon by consulting sundials and astronomical tables. According to Selling the True Time, a common arrangement at the time was to designate a jeweler as a city’s official timekeeper. Atkin appointed Chicago's first official timekeeper. A large ball dropped from a high place and visible throughout a city was the answer. However, since sound takes 4.7 seconds to travel a mile, far-away observers would get inaccurate signals. Bells and guns had long been used to transmit time. This didn't affect ordinary people much, they still got up and went to bed with the sun. Circa 1800: accurate chronometers and advanced astronomy now allowed time to be transferred over a distance.Still, especially since there was no means or desire of transferring a time signal over any distance, every place observed local solar time. Time began, at least for scientists, to be thought of as constant, rather than varying with the seasons. Circa 1600: mechanical clocks were developed in Europe allowing somewhat accurate measurements of intervals of time.However, time measurement continued to be based on the concepts of darkness, light and noon. Water clocks allowed the measurement of intervals of time.
Prehistoric times: several cultures developed means of measuring solar time, such as sundials.Often a city had not only its local time, but each railroad passing through the city used yet a different time-meaning that railroad stations needed multiple clocks. The railroads themselves used 49 time zones. This meant that when it when it was noon in Washington, D.C., it was 12:02 in nearby Baltimore, 12:07 in Philadelphia, 12:12 in New York, 11:17 in Chicago, etc. used its own time based on the local solar noon. This began a slow worldwide conversion to time zones based on the Greenwich meridian. The Convention adopted "Standard Time" with four time zones, each offset by an exact number of hours from English standard time. for less than 100 years.Ĭhicago played a pivotal part, being the site of the 1883 General Time Convention. It is difficult for us to realize that this system only started 132 years ago. Today, everybody may show up at a meeting within seconds of each other and every part of the world is in a time zone offset from English time by an exact number of hours (in some cases by 15, 30 or 45 minutes). Plaque at LaSalle and Jackson commemorating the 1883 General Time Convention.
0 kommentar(er)
