81 Getting a Handle on Time
When it is 10:15 in New York, it is 9:15 in Chicago, 8:15 in Salt Lake City, and 7:15 in San Francisco. Isn’t it consistent and orderly? This system based on a grid of time zones, seems so natural that people rarely give it a moment’s thought. So you may find it surprising to learn that prior to the late 1800s each community determined its own time, for example, in Boston it was 12:00 noon there, up the road in Philadelphia, however, it was 12:07, and in Washington, D.C., it was 12:24. To measure time with absolute accuracy, it is necessary to move the clock about one minute for every twelve miles of distance, so according to “sun time,” your pocket watch would be slightly incorrect if you ventured only a few miles down the road.
It was not until the advent of widespread railroad travel that a need for a consistently recognized time arose. You needed the correct time literally. One could over 300 miles were honored within the country, making it impossible for trains to arrive consistently on time every. As a result, in 1883 the continental United States was divided into four time zones, centered on approximately the 75th, 90th, 105th, and 120th meridians of longitude.
The standardization resulting from this system proved so helpful that in 1884 the International Meridian Conference applied the same procedure to establish time zones around the world. Thus, if it is 11:07 p.m. in Tuscaloosa, Alabama, it is 9:07 a.m.—and nor 9:15, a little simple research will quickly determine that in Kuala Lumpur, Malaysia, it is
81 掌握时间
在纽约是10:15的时候，芝加哥是9:15，盐湖城是8:15，旧金山是7:15。这难道不是既一致又有序吗？这种基于时区网格的系统看起来如此自然，以至于人们很少对此多想。所以你可能会惊讶地发现，在19世纪晚期之前，每个社区都自行确定时间——比如，波士顿是正午12点时，不远处的费城是12:07，而华盛顿特区是12:24。要绝对准确地测量时间，每12英里的距离就需要把时钟调快约一分钟，所以根据“太阳时”，哪怕你只走了几英里路，你的怀表也会稍有不准。
直到铁路旅行普及后，人们才产生了对统一时间的需求。你确实需要准确的时间。全国范围内有超过300英里的区域采用不同时间，这让火车根本无法始终准点到达。因此，1883年，美国大陆被划分为四个时区，大致以经度75°、90°、105°和120°为中心。
这套系统带来的标准化效果非常好，以至于1884年国际子午线会议采用了同样的方法，在全球范围内建立时区。因此，如果阿拉巴马州塔斯卡卢萨是晚上11:07，那么马来西亚吉隆坡的时间是早上9:07（而非9:15）——只需简单查证就能快速确定这一点。