【課文】
First listen and then answer the following question.
聽錄音，然后回答以下問題。
What does a pen have to do to record on paper the vibrations generated by an earthquake?
An earthquake comes like a thief in the night, without warning. It was necessary, therefore, to invent instruments that neither slumbered nor slept. Some devices were quite simple. One, for instance, consisted of rods of various lengths and thicknesses which would stand up on end like ninepins. When a shock came, it shook the rigid table upon which these stood. If it were gentle, only the more unstable rods fell. If it were severe, they all fell. Thus the rods, by falling, and by the direction in which they fell, recorded for the slumbering scientist the strength of a shock that was too weak to waken him, and the direction from which it came.
But instruments far more deliecate than that were needed if any really serious advance was to be made. The ideal to be aimed at was to devise an instrument that could record with a pen on paper, the movements of the ground or of the table as the quake passed by. While I write my pen moves, but the paper keeps still. With practice, no doubt, I could in time learn to write by holding the pen still while the paper moved. That sounds a silly suggestion, but that was precisely the idea adopted in some of the early instruments (seismometers) for recording earthquake waves. But when table, penholder and paper are all moving, how is it possible to write legibly? The key to a solution of that problem lay in an everyday observation. Why does a person standing in a bus or train tend to fall when a sudden start is made? It is because his feet move on , but his head stays still. A simple experiment will help us a little further. Tie a heavy weight at the end of a long piece of string. With the hand held high in the air, hold the string so that the weight nearly touches the ground. Now move the hand to and fro and around but not up and down. It will be found that the weight moves but slightly or not at all. Imagine a pen attached to the weight in such a way that its point rests upon a piece of paper on the floor. Imagine an earthquake shock shaking the floor, the paper, you and your hand. In the midst of all this movement, the weight and the pen would be still. But as the paper moved from side to side under the pen point, its movement would be recorded in ink upon its surface. It was upon this principle that the first instruments were made, but the paper was wrapped round a drum which rotated slowly. As long as all was still, the pen drew a straight line, but while the drum was being shaken, the line that the pen was drawing wriggled from side to side. The apparatus thus described, however, records only the horizontal component of the wave movement, which is, in fact, much more complicated. If we could actually see the path described by a particle, such as a sand grain in the rock, it would be more like that of a bluebottle path described by a particle, such as a sand grain in the rock, it would be more like that of a bluebottle buzzing round the room; it would be up and down, to and fro and from side to side. Instruments have been devised and can be so placed that all three elements can be recorded in different graphs.
When the instrument is situated at more than 700 miles from the earthquake centre, the graphic record shows three waves arriving one after the other at short intervals. The first records the arrival of longitudinal vibrations. The second marks the arrival of transverse vibrations which travel more slowly and arrive several minutes after the first. These two have travelled through the earth. It was from the study of these that so much was learnt about the interior of the earth. The third, or main wave, is the slowest and has travelled round the earth through the surface rocks.
H.H,SWINNERTON The Earth beneath Us
【New words and expressions 生詞和短語】
earthquake n. 地震
slumber v. 睡眠
ninepin n. 九柱戲中的木柱
rigid adj. 堅(jiān)硬的
delicate adj. 靈感的
seismometer n. 地震儀
penholder n. 筆桿
legibly adv. 字跡清楚地
drum n. 鼓狀物
wriggle v. 扭動(dòng)
bluebottle n. 綠頭蒼蠅
graph n. 圖表
graphic adj. 圖示的
longitudinal adj. 縱向的
transverse adj. 橫向的
【課文注釋】
1.slumber v.睡眠
例句：She fell into restful slumber.
她進(jìn)入寧靜的安眠之中。
Allow no sleep to your eyes, no slumber to your eyelids.
不要容你的眼睛睡覺，不要容你的眼皮打盹。
【詞義辨析】
sleep, doze, nap, slumber 這些動(dòng)詞均含“睡”之意。
sleep : 普通用詞，指一般的睡眠?？捎米饕曛搁L眠或靜止不動(dòng)。
doze : 多用于口語中，指輕微的小睡或處于半睡狀態(tài)。
nap : 指白天的小睡。
slumber : 多指人安詳?shù)鼗蜷L時(shí)間地睡。
2. stand up on end 豎立著
3.rigid adj.堅(jiān)硬的;刻板的
例句：The tent has a rigid support.
帳篷有一個(gè)堅(jiān)硬的支柱。
He's very rigid in his ideas.
他的想法非常固執(zhí)。
【詞義辨析】
rigid, strict, rigorous這些形容詞均含“刻板的，嚴(yán)格的”之意。
rigid: 指沒有靈活性、機(jī)動(dòng)性。
strict: 指在行為規(guī)則上要求嚴(yán)格。
rigorous: 側(cè)重指嚴(yán)格到毫不寬容的地步。
4.The ideal to be aimed at 理想的目標(biāo)
5.devise vt. 設(shè)計(jì)， 發(fā)明， 遺贈(zèng)
例句：This time we'll devise a better solution.
這次我們將設(shè)計(jì)一種新的解決方案。
He devised a new type of transistor.
他發(fā)明了一種新的晶體管。
【詞義辨析】
devise, conceive, formulate 這些動(dòng)詞的均含“設(shè)計(jì)、設(shè)想”之意。
devise: 側(cè)重設(shè)計(jì)的臨時(shí)性和權(quán)宜性，并隱含有更多的設(shè)想可用。
conceive: 強(qiáng)調(diào)在制定計(jì)劃之前的先有設(shè)想構(gòu)思。
formulate: 與conceive相反，指在devise之后的具體設(shè)計(jì)活動(dòng)。
6.I could in time 我終能夠……
7.legibly adv.字跡清楚地
例句：He can write as neatly and legibly as the next person if he takes his time over it.
若他不匆匆忙忙寫的話，他能寫得和別人一樣整潔、清楚。
8.help us a little further 幫助我們進(jìn)一步搞清這個(gè)問題
9.With the hand held high in the air, hold the string 這是一個(gè)祈使句，謂語動(dòng)詞是hold, with the hand held high in the air是介詞短語作方式狀語。
10.to and fro 往復(fù)，來來回回
11.rotate v. 輪流，(使)旋轉(zhuǎn)
例句：He rotates the handle gently.
他輕輕地轉(zhuǎn)動(dòng)手柄。
The post of chairman rotates among members of the committee.
主席一職由委員會(huì)的成員輪流擔(dān)任。
【詞義辨析】
rotate, revolve, roll, spin, turn, whirl, circle 這些動(dòng)詞均有“轉(zhuǎn)動(dòng)、旋轉(zhuǎn)”之意。
rotate: 側(cè)重指物體圍繞自己的軸或中心旋轉(zhuǎn)，即自轉(zhuǎn)。
revolve: 強(qiáng)調(diào)指物體圍繞本身以外的中心旋轉(zhuǎn)，即公轉(zhuǎn)。
roll: 指某物在平面上滾動(dòng)或翻滾。
spin: 指沿內(nèi)軸迅速而連續(xù)旋轉(zhuǎn)，或沿外部一個(gè)點(diǎn)作快速圓周運(yùn)轉(zhuǎn)。
turn: 普通用詞，中性，含義廣泛，根據(jù)搭配，可指作一個(gè)圓周運(yùn)動(dòng)或連續(xù)地作圓周運(yùn)動(dòng)，也可指僅是沿圓的弧形轉(zhuǎn)動(dòng)。
whirl: 指旋轉(zhuǎn)或作圓周運(yùn)動(dòng)，側(cè)重急速或力量。
circle: 指作圓周運(yùn)動(dòng)。
12.wriggle v.扭動(dòng)
例句：I can't brush your hair if you keep wriggling all the time.
你要是一直扭來扭去，我就沒法給你梳頭了。
He had to wriggle his way out.
他得扭著身子才鉆了出來。
13.vibration n.顫動(dòng);振動(dòng);搖動(dòng)
例句：Even at full speed the ship's engines cause very little vibration.
這條船即使全速前進(jìn)，發(fā)動(dòng)機(jī)的震動(dòng)也很小。
【參考譯文】
地震就像夜間的小偷，不打招呼就來了。因此，有必要發(fā)明一種儀器，既不打盹兒，也不睡覺。有些裝置非常簡單。例如，有一種裝置是由一些長短、粗細(xì)不同的木棒組成，就像九柱戲的木棒一樣堅(jiān)立著，一旦有地震，就會(huì)震動(dòng)豎立在堅(jiān)硬的桌上的木棒。如果地震輕微，只有不穩(wěn)定的木棒倒下;如果地震劇烈，所有的木棒都會(huì)例下。由于地震太弱而未驚醒科學(xué)家時(shí)，木棒倒下的多少和倒下的方向就為科學(xué)家記錄下了地震的強(qiáng)度和地震方向。
但是，如果要取得真正重大的進(jìn)展，需要有比這種裝置精細(xì)得多的儀器。理想的目標(biāo)是設(shè)計(jì)出這樣一種儀器：當(dāng)?shù)卣鸢l(fā)生時(shí)，它能用筆在紙上記錄下大地和桌子運(yùn)動(dòng)情況。我寫字時(shí)，筆是移動(dòng)的，紙是靜止的。毫無疑問，經(jīng)過練習(xí)，我終能夠?qū)W會(huì)筆不動(dòng)而紙動(dòng)來寫字。這聽起來似乎是一種愚蠢的想法，但是早期記錄地震波的儀器(地震儀)正是采用了這種思路。可是，當(dāng)桌子、夾筆裝置、紙都在移動(dòng)時(shí)，怎么能書寫得清楚呢?可以從我們的日常生活觀察中找到這個(gè)問題的答案。一個(gè)站在公共汽車或火車上，當(dāng)車突然開動(dòng)時(shí)，他為什么會(huì)傾倒呢?這是因?yàn)樗哪_動(dòng)了，而他的頭保持著靜止。再做一個(gè)簡單的實(shí)驗(yàn)可以幫助我們進(jìn)一步理解這個(gè)問題。把一個(gè)生物拴在一根長繩子的一端，把手高高舉在空中握住繩子，讓重物幾乎接觸地面。然后把手前后左右以及旋轉(zhuǎn)擺動(dòng)，但不要上下擺動(dòng)。結(jié)果會(huì)發(fā)現(xiàn)，重物是動(dòng)了，但動(dòng)得很小，甚至沒動(dòng)。假定把一支筆拴在重物上，筆尖落在地板上的一張紙上，假定地震發(fā)生了，地板、紙、你和你的手都會(huì)動(dòng)，重物和筆卻不動(dòng)。由于紙?jiān)诠P下來回運(yùn)動(dòng)，紙的表面就會(huì)用墨水記錄下地板運(yùn)動(dòng)的情況。根據(jù)這一原理，制造出了初的地震儀器，但是紙是卷在慢慢放置的圓筒上的。只要一切都是靜止的，筆就會(huì)劃出一條直線;但是，圓筒受到震動(dòng)，筆所畫出的線就會(huì)就會(huì)左右擺動(dòng)。然而，這里所說的儀器記錄下來的只是地震波運(yùn)動(dòng)中的水平部份，地震波的運(yùn)動(dòng)實(shí)際比這要復(fù)雜得多。假如我們真能看到諸如巖石中一個(gè)沙粒子的運(yùn)動(dòng)軌跡，那就像一只嗡嗡叫的綠頭蒼蠅在屋內(nèi)飛行的軌跡，呈現(xiàn)出上上下下、來來回回、左左右右3種性質(zhì)的運(yùn)動(dòng)。已經(jīng)設(shè)計(jì)出了一些儀器，它按照一定的安放方式就可測(cè)繪出這三種運(yùn)動(dòng)的曲線圖。
如果把這種儀器安裝在距震中700多英里遠(yuǎn)的地方，曲線記錄就能顯示出前后相同的這3種地震波。首先記錄下的是縱向波的到達(dá);然后記錄下的是橫向波的到達(dá)，橫向波比縱向波傳播得慢，在縱向波到過幾分鐘后能到達(dá)。這兩種波都是穿過地球而來的。正是從這兩種波中的研究中，我們可以了解到地球內(nèi)部的許多情況。第三種波，即主波，是慢的，是圍繞地球通過表面巖石傳來的。