有聲英文閱讀-為什么我們會走成兩個大圓圈

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Why We Walk in Circles

It is a well-known fact that a person will move in a circle when he cannot use his eyes to control his direction. Dark nights, dense fogs, blinding snowstorms, thick forests - all these can keep a traveler from seeing where he is going. Then he is unable to move in any fixed direction, but walks in circles.
Animals act the same way. You have probably heard the saying "running around like a chicken with its head cut off." Well, a chicken with its head cut off actually does run around in circles. Blind birds fly in circles. And a blindfolded dog will swim in circles.
A Norwegian biologist, F.O.Guldberg, decided that this problem of circular movement was worth investigating. He collected many true stories on the subject.
One of his stories is about people rowing on a lake during a fog on a dark night. One group of rowers who tried to cross three miles of water in foggy weather never succeeded in reaching their goal. Without knowing it, they rowed in two large circles. When they finally got to the shore, they discovered that they were at the spot they had started from.
After studying many stories such as this, Professor Guldberg wrote an article in which he discussed "Circular Motion as the Basic Motion of Animals." A simple example will help you to understand his explanation of why we walk in circles.
Have you ever wound up a toy automobile and started it off across the floor? Then you know that it will rarely travel in a straight path. It will travel, instead, in some kind of arc, or curve. If it is to travel in a straight line, the wheels on both sides have to be of exactly equal size. If they are not, the little automobile turns toward the side with the smaller wheels.
Circular movement in walking is caused in much the same way. Usually a man walking will "watch his step" and "look where he is going." He needs his senses, especially his eyes, to get to the point he intends to reach. When he cannot use his eyes to guide his steps, he will walk straight only if he takes a step of the same length with each foot.
In most people, however, muscle development is not the same in both legs, so that it is probable that the steps will be uneven. The difference may be so small that no one is aware of it. But small as it is, it can cause circular movement.
Let us suppose that a man's left foot takes a step 20 inches long and that his right foot takes a step 30 inches long. Now suppose he takes ten step - five with his left foot and five with his right. His left foot will travel 100 inches. His right foot will travel 150 inches. This sounds impossible. One foot cannot remain 50 inches behind the other. What really happens? At each step the man turns a little bit to the left. Sooner or later he makes a complete circle. The tracks of his feet, however, make two circles, one inside the other. His left foot makes the smaller circle because it is taking larger steps. This is why a person may walk in an arc when he sets out in a straight line.
The muscles of a man's arms are no more identical than the muscles of his legs. This explains why the rowers who set out to cross the lake at night rowed in a circle. By the same rule, a bird's wings do not develop evenly, and so it will fly in circles when blinded. Thus, dear readers, our circular mystery has a very straight answer.

為什么我們會走成兩個大圓圈

觀看別人做"去把尾巴給毛驢安上"的游戲，比自己親自去做更逗人。看到了被蒙住眼睛的參加游戲表演的人所走的路線著實(shí)有點(diǎn)兒讓人吃驚。他們都不走直線，總是要由一邊偏離到另一邊。參加游戲比賽的人距離毛驢越遠(yuǎn)，他們偏離目標(biāo)毛驢也越遠(yuǎn)。
一個人若不用眼睛來掌握走路的方向，就會走成一個大圈。這一事實(shí)是眾所周知的。每遇到漆黑的夜晚，濃濃的大霧，伸手不見五指的暴風(fēng)雪，濃密森林--這一切都會使路上的行人看不見是在往哪個方向走。這時他就不能按既定的目標(biāo)前進(jìn)，只能走成一個大圓圈。
動物也會這樣。你也許聽過這樣一句老話："像砍掉腦袋的雞一樣轉(zhuǎn)著圈跑。"是的，一只被砍掉了腦袋的雞確實(shí)會轉(zhuǎn)著圈跑的。瞎了眼睛的鳥也都是轉(zhuǎn)著圈飛的。一雙被蒙住了眼睛的狗也會轉(zhuǎn)著大圈游泳。一位挪威的生物學(xué)家哥爾柏格認(rèn)為繞圈運(yùn)動的問題確實(shí)值得調(diào)查研究。關(guān)于這一課題他匯集了很多實(shí)際事例。
他匯集的實(shí)例之一就是在一個濃霧黑夜里，人們在湖面上劃般。在大霧的天氣里，一幫想要橫渡三英里的水面的劃船手永遠(yuǎn)也不能成功地劃到他們的目的地。不知不覺地，他們都把船劃行路線劃成兩個大圈。在他們綞上個岸后，才發(fā)現(xiàn)又劃回到了他們原來出發(fā)的地點(diǎn)。
在研究過很多諸如此類的實(shí)際經(jīng)歷之后，哥爾柏格教授寫了一篇題為《動物的基本運(yùn)動模式是圓周運(yùn)動》的論文。一個很簡單的的例子，就可以幫助你弄明白他的論點(diǎn)：為什么我們會走成兩個大圓圈。
你有沒有把一輛玩具汽車上好發(fā)條以后，把它放到地板上讓它從頭跑到那頭的經(jīng)歷？那么，你就會知道小汽車幾乎很少順著直線跑，那么它左右兩邊的車輪的大小必須是正好絕對相等的。
步行時繞大圓周運(yùn)動的規(guī)律在很大程度上是由同一原理引起的。通常一個人走路時會看著腳下所踩的步子，會看著所要去的方向。一個人需要用他們的各種器官，特別是要用兩只眼睛，才能走到他打算要去的地點(diǎn)。只有當(dāng)一個人的兩只腳所邁出的每一步的長短都完全相同時，這個人才可以不用眼睛來引導(dǎo)腳步而能夠順著一條直線往前走。
但是，在絕大多數(shù)人左右兩腿肌肉的發(fā)育并不是一樣的，結(jié)果很可能左右兩腳所邁的步子長短是不一致的。邁步子長短的差距是非常小的，以致于沒有人會意識到這一微小的差距。盡管這個差距很小，但結(jié)果卻導(dǎo)致了圓周運(yùn)動。
我們假定某一人的左腳邁一步是20英寸長，右腳萬一步是30英寸長。現(xiàn)在假設(shè)這個人邁了十步--左腳邁五步，右腳也邁五步。他的左腳總共走了100英寸，他的右腳總共走了150英寸。這聽起來讓人覺得不可能。到底是怎么回事呢？每邁一步這個人就稍微向左轉(zhuǎn)了一點(diǎn)點(diǎn)。遲早，他會走成一個大圓圈。于是他的兩只腳所走過的圓圈稍微小一點(diǎn)，因?yàn)樽竽_邁的步子小。他的右腳所走的圈比較大，因?yàn)橛夷_的每一步都大一點(diǎn)。這就是一個人在出發(fā)時本來是想走的直線，結(jié)果卻走成了一條弧線的原因。
一個人的兩只胳膊肌肉的發(fā)育和他的兩只腿的肌肉的發(fā)育也是不同的。這足可以說明這些在夜間出發(fā)去橫渡湖面的劃船手綞把船劃行的路線劃成了一個大圓圈的道理。同理，鳥的左右兩個翅膀的發(fā)育也是不均衡的，所以如果它的眼睛瞎了以后，也會繞圓圈飛行。由此可見，親愛的讀者，這就是我們的圓圈運(yùn)動之迷的最直截了當(dāng)?shù)拇鸢浮?/p>