万物简史 第52期:事物的测定(10)

Newton's laws explained so many things—the sloshand roll of ocean tides, the motions of planets, whycannonballs trace a particular trajectory beforethudding back to Earth, why we aren't flung intospace as the planet spins beneath us at hundreds ofmiles an hour—that it took a while for all theirimplications to seep in. But one revelation becamealmost immediately controversial.

牛顿定律解释了许许多多事情--海洋里潮水的飞溅和翻腾;行星的运动;为什么炮弹着地前沿着一条特定的弹道飞行;虽然我们脚下的行星在以每小时几百公里的速度旋转，为什么我们没有被甩进太空--这些定律的全部意义要费好大工夫才能领会。但是，它们揭示的事实几乎马上引发了争议。

This was the suggestion that the Earth is not quite round. According to Newton's theory, thecentrifugal force of the Earth's spin should result in a slight flattening at the poles and abulging at the equator, which would make the planet slightly oblate. That meant that thelength of a degree wouldn't be the same in Italy as it was in Scotland. Specifically, the lengthwould shorten as you moved away from the poles. This was not good news for those peoplewhose measurements of the Earth were based on the assumption that the Earth was a perfectsphere, which was everyone.

这意味着，地球不是滴溜滚圆的。根据牛顿的学说，地球自转产生的离心力，造成两极有点扁平，赤道有点鼓起。因此，这颗行星稍稍呈扁圆形。这意味着，1度经线的长度，在意大利和苏格兰是不相等的。说得确切一点，离两极越远，长度越短。这对那些认为地球是个滴溜滚圆的球体，并以此来测量这颗行星的人来说不是个好消息。那些人就是大家。

For half a century people had been trying to work out the size of the Earth, mostly by makingvery exacting measurements. One of the first such attempts was by an English mathematiciannamed Richard Norwood. As a young man Norwood had traveled to Bermuda with a diving bellmodeled on Halley's device, intending to make a fortune scooping pearls from the seabed. Thescheme failed because there were no pearls and anyway Norwood's bell didn't work, butNorwood was not one to waste an experience. In the early seventeenth century Bermuda waswell known among ships' captains for being hard to locate. The problem was that the oceanwas big, Bermuda small, and the navigational tools for dealing with this disparity hopelesslyinadequate. There wasn't even yet an agreed length for a nautical mile. Over the breadth ofan ocean the smallest miscalculations would become magnified so that ships often missedBermuda-sized targets by dismaying margins. Norwood, whose first love was trigonometry andthus angles, decided to bring a little mathematical rigor to navigation and to that end hedetermined to calculate the length of a degree.

在半个世纪的时间里，人们想要测算出地球的大小，大多使用很严格的测量方法。最先做这种尝试的人当中有一位英国数学家，名叫理查德·诺伍德。诺伍德在年轻时代曾带着个按照哈雷的式样制作的潜水钟去过百慕大，想要从海底捞点珍珠发大财。这个计划没有成功，因为那里没有珍珠，而且诺伍德的潜水钟也不灵，但浪费一次经历的也不止诺伍德一个人。17世纪初，百慕大在船长中间以难以确定位置著称。问题是海洋太大，百慕大太小，用来解决这个差异的航海仪器严重不足。连1海里的长度还都说法不一。关于海洋的宽度，最细小的计算错误也会变得很大，因此船只往往以极大的误差找不到百慕大这样大小的目标。诺伍德爱好三角学，因此也爱好三角形，他想在航海方面用上一点数学，于是决定计算1度经线的长度。