by helio`(680)一屏多。第一段讲某个年份，某某发明了pendulum clock，这个钟已经被什么使用，然后讲了它是如何运作的，有时针和分针，时针通过某个装置运动，然后分针通过一个什么linkage, 好像是electronic device之类的运动，时针转动多少分针转动多少blahblah..好像也讲到了它的精确度。
By 大个钊(710)还有一个是超长的，讲clock 它的design 还有在某个阶段是作为衡量时间标准的，然后又讲了一哥们做了个实验发现了一个自然现象(太长了没必要全读)有问到主旨
by ephemeral00关于pendulum clock的，说这个东东如何如何的巨准无比，以至于能用它来发现tide change on earth什么的。然后提到了一个人，好像对这个钟做了啥深入的研究，发现了些啥东东(洋洋洒洒写了2段，我都没太仔细看)。。。
2.1) 问这个钟导致了什么发现。我选了发现tide change。
2.2 ) 问其中一个pendulum(这个钟有2个pendulum)所在的chamber有何特点。文中提到chamber是vacuum的，所以我选了sealed so that no air can get in什么的。
2.3) 问这片文章用意何在。我选的好像是衡量一个东东(就是钟)功能准确不准确什么的。
考古(已确认) 我爱忽然MM~~~~
一种异常准确的机械钟。(难，高分区)
第一段：说这种钟可以说是世界上最后的机械钟了，而且有两个，一个在爱丁堡，一个在某observing station.(记不清了，但此处无题)。这种钟就两个钟摆(pendulum), the first 在一个真空(vacuum)的容器中(此处对真空有题)，另一个来管钟的各指针(大概是这个意思)。第一个钟摆会适时第第二个钟摆信号，来进行适度调整。这个钟就是靠这个运行的
1)What is truth about the first pendulum (in the first paragraph)?
基金主人选和真空有关的
2)Which of the following can NOT be experimented in 1984?
基金主人选了一个更准确的钟。
3)What does this clock coincidentally find?
基金主人选地球转速因引力而不同。(有人说这个选项有问题)
因为原文说的是seasonal rotation. 但是答案里面是year one year 的rotation。所以没选这个，那个人选的是对大陆，海洋的tidal都有影响。(请大家确认)
网上找到的，据说仿真度较高，请大家仔细阅读
The Shortt clock had two pendulums. The first, known as the master, swung freely in an evacuated case. Its only job was to synchronize the swing of the second pendulum, called the slave, which was housed in a neighboring cabinet. Every 30 seconds the slave sent an electrical signal to give a nudge to the master. In return, via an elaborate electromechanical link, the master ensured that the slave never got out of step.
Shortt clocks were standard provision in astronomical observatories of the 1920s and 1930s, and are credited with keeping time to better than 2 milliseconds a day. Many were on record as losing or gaining no more than 1 second a year – a stability of one part in 30 million. The first indications of seasonal variations in the Earth’s rotation were gleaned by the use of Shortt clocks.
In 1984 Pierre Boucheron carried out a study of a Shortt clock which had survived in the basement of the US Naval Observatory since 1932. Using the modern optical sensing equipment instead of the electromechanical coupling, he measured its rate against the observatory’s atomic clocks for a month. He found that it was stable to 200 microseconds a day over this period, equivalent to two to three parts in a billion. What is more, the data also reveal that the clock was sensing the distortion of the Earth due to tides from the Moon and the Sun.
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发表于 2010-10-23 15:25:16
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