萬物簡史 第60期:事物的測定(18)

Soon afterward, Maskelyne returned to Englandwhere he became astronomer royal, and Mason andDixon—now evidently more seasoned—set off for fourlong and often perilous years surveying their waythrough 244 miles of dangerous Americanwilderness to settle a boundary dispute betweenthe estates of William Penn and Lord Baltimore andtheir respective colonies of Pennsylvania andMaryland.

此后不久，馬斯基林回到英國，成為皇家天文學(xué)家，而梅森和狄克遜--這時候顯然更加成熟--啟程前往美洲，度過漫長而時常是險象環(huán)生的4年。他們穿越393公里危險的荒原，一路上搞測量工作，以解決威廉·佩恩和巴爾的摩勛爵兩人地產(chǎn)之間的以及他們各自殖民地--賓夕法尼亞和馬里蘭--之間的邊界糾紛。

The result was the famous Mason and Dixon line, which later took on symbolic importance asthe dividing line between the slave and free states. (Although the line was their principal task,they also contributed several astronomical surveys, including one of the century's mostaccurate measurements of a degree

of meridian—an achievement that brought them far more acclaim in England than thesettling of a boundary dispute between spoiled aristocrats.)

結(jié)果就是那條著名的梅森-狄克遜線。后來，這條線象征性地被看做是美國奴隸州和自由州之間的分界線。(這條線是他們的主要任務(wù)，但他們還進行了幾次天文觀測。其中有一次，他們對1度經(jīng)線的長度作了當(dāng)時那個世紀(jì)最精確的測量。由于這項成就，他們在英國贏得了比解決兩位被寵壞了的貴族之間的邊界糾紛高得多的贊揚。)

Back in Europe, Maskelyne and his counterparts in Germany and France were forced to theconclusion that the transit measurements of 1761 were essentially a failure. One of theproblems, ironically, was that there were too many observations, which when brought togetheroften proved contradictory and impossible to resolve.

回到歐洲以后，馬斯基林與他的德國和法國同行不得不下結(jié)論，1761年的凌日觀測工作基本失敗。具有諷刺意味的是，問題之一在于觀測的次數(shù)太多。把觀測結(jié)果放在一起，往往證明互相矛盾，無法統(tǒng)一。

The successful charting of a Venusian transit fell instead to a little-known Yorkshire-born seacaptain named James Cook, who watched the 1769 transit from a sunny hilltop in Tahiti, andthen went on to chart and claim Australia for the British crown. Upon his return there was nowenough information for the French astronomer Joseph Lalande to calculate that the meandistance from the Earth to the Sun was a little over 150 million kilometers. (Two further transitsin the nineteenth century allowed astronomers to put the figure at 149.59 million kilometers,where it has remained ever since. The precise distance, we now know, is 149.597870691million kilometers.) The Earth at last had a position in space.

成功繪制金星凌日圖的卻是一位不知名的約克郡出生的船長，名叫詹姆斯·庫克。他在塔希提島一個陽光普照的山頂上觀看了1769年的凌日現(xiàn)象，接著又繪制了澳大利亞的地圖，宣布它為英國皇家殖民地。他一回到國內(nèi)，就聽說法國天文學(xué)家約瑟夫·拉朗德已經(jīng)計算出，地球到太陽的平均距離略略超過1.5億公里。(19世紀(jì)又發(fā)生兩次凌日現(xiàn)象，天文學(xué)由此得出的距離是1.4959億公里，這個數(shù)字一直保持到現(xiàn)在。我們現(xiàn)在知道，確切的距離應(yīng)該是1.495 978 706 91億公里。)地球在太空中終于有了個方位。