萬物簡(jiǎn)史 第52期:事物的測(cè)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.

牛頓定律解釋了許許多多事情--海洋里潮水的飛濺和翻騰;行星的運(yùn)動(dòng);為什么炮彈著地前沿著一條特定的彈道飛行;雖然我們腳下的行星在以每小時(shí)幾百公里的速度旋轉(zhuǎn)，為什么我們沒有被甩進(jìn)太空--這些定律的全部意義要費(fèi)好大工夫才能領(lǐng)會(huì)。但是，它們揭示的事實(shí)幾乎馬上引發(fā)了爭(zhēng)議。

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.

這意味著，地球不是滴溜滾圓的。根據(jù)牛頓的學(xué)說，地球自轉(zhuǎn)產(chǎn)生的離心力，造成兩極有點(diǎn)扁平，赤道有點(diǎn)鼓起。因此，這顆行星稍稍呈扁圓形。這意味著，1度經(jīng)線的長(zhǎng)度，在意大利和蘇格蘭是不相等的。說得確切一點(diǎn)，離兩極越遠(yuǎn)，長(zhǎng)度越短。這對(duì)那些認(rèn)為地球是個(gè)滴溜滾圓的球體，并以此來測(cè)量這顆行星的人來說不是個(gè)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.

在半個(gè)世紀(jì)的時(shí)間里，人們想要測(cè)算出地球的大小，大多使用很嚴(yán)格的測(cè)量方法。最先做這種嘗試的人當(dāng)中有一位英國數(shù)學(xué)家，名叫理查德·諾伍德。諾伍德在年輕時(shí)代曾帶著個(gè)按照哈雷的式樣制作的潛水鐘去過百慕大，想要從海底撈點(diǎn)珍珠發(fā)大財(cái)。這個(gè)計(jì)劃沒有成功，因?yàn)槟抢餂]有珍珠，而且諾伍德的潛水鐘也不靈，但浪費(fèi)一次經(jīng)歷的也不止諾伍德一個(gè)人。17世紀(jì)初，百慕大在船長(zhǎng)中間以難以確定位置著稱。問題是海洋太大，百慕大太小，用來解決這個(gè)差異的航海儀器嚴(yán)重不足。連1海里的長(zhǎng)度還都說法不一。關(guān)于海洋的寬度，最細(xì)小的計(jì)算錯(cuò)誤也會(huì)變得很大，因此船只往往以極大的誤差找不到百慕大這樣大小的目標(biāo)。諾伍德愛好三角學(xué)，因此也愛好三角形，他想在航海方面用上一點(diǎn)數(shù)學(xué)，于是決定計(jì)算1度經(jīng)線的長(zhǎng)度。