新概念英語第四冊
Lesson 42 Recording an earthquake
1 . If it were severe, they all fell.如果地震劇烈，所有的木棒都會倒下。
2 . These two have travelled through the earth.這兩種波都是穿過地球而來的。
3 . it would be up and down, to and for and from side to side.呈現出上上下下、來來回回、左左右右3種性質的運動。
4 . While I write my pen moves, but the paper keeps still.我寫字時，筆是移動的，紙是靜止的。
5 . As long as all was still, the pen drew a straight line,只要一切都是靜止的，筆就會劃出一條直線；
6 . which is, in fact, much more complicated.地震波的運動實際比這要複雜得多。
7 . The third, or main wave,第三種波，即主波，
8 . The second marks the arrival of transverse vibrations which travel more slowly and arrive several minutes after the first.然後記錄下的是橫向波的到達，橫向波比縱向波傳播得慢，在縱向波到達幾分鐘後才能到達。
9 . Imagine an earthquake shock shaking the floor, the paper, you and your hand.假定地震發生了，地板、紙、你和你的手都會動，
10 . but that was precisely the idea adopted in some of the early instruments (seismometers) for recording earthquake waves.但是早期記錄地震波的儀器（測震儀）正是採用了這種思路。
11 . Now move the hand to and fro and around but not up and down.然後把手前後左右以及旋轉擺動，但不要上下擺動。
12 . hold the string so that the weight nearly touches the ground.讓重物幾乎接觸地面。
13 . but while the drum was being shaken,但是，圓筒受到震動，
14 . Instruments have been devised and can be so placed that all three elements can be recorded in different graphs.已經設計出了一些儀器，它按照一定的安放方式就可測繪出這三種運動的曲線圖。
15 . The apparatus thus described, however,然而，這裡所說的儀器
16 . It is because his feet move on, but his head stays still.這是因為他的腳動了，而他的頭保持著靜止。
17 . It will be found that the weight moves but slightly or not at all.結果會發現，重物是動了，但動得很小，甚至沒動。
18 . Thus the rods, by falling, and by the direction in which they fell,木棒倒下的多少和倒下的方向
19 . It was upon this principle that the first instruments were made,據這一原理，製造出了最初的地震儀器，
20 . Some devices were quite simple.有些裝置非常簡單。
21 . One, for instance, consisted of rods of various lengths and thicknesses which would stand up on end like ninepins.例如，有一種裝置是由一些長短、粗細不同的木棒組成；就像九柱戲的木棒一樣豎立著，
22 . but the paper was wrapped round a drum which rotated slowly.根但是紙是卷在慢慢旋轉的圓筒上的。
23 . But as the paper moved from side to side under the pen point,由於紙在筆尖下來回運動，
24 . The key to a solution of that problem lay in an everyday observation.可以從我們的日常生活觀察中找到這個問題的答案。
25 . Tie a heavy weight at the end of a long piece of string.把一個重物拴在一根長繩子的一端，
26 . recorded for the slumbering scientist the strength of a shock that was too weak to waken him,and the direction from which it came.由於地震太弱而未驚醒科學家時，就為科學家記錄下了地震的強度和地震方向。
27 . With the hand held high in the air,把手高高舉在空中握住繩子，
28 . the line that the pen was drawing wriggled from side to side.筆所畫出的線就會左右擺動。
29 . Why does aperson standing in a bus or train tend to fall when a sudden start is made?一個人站在公共汽車或火車上，當車突然開動時，他為什麼會傾倒呢？
30 . The ideal to be aimed at was to devise an instrument that could record with a pen on paper,當地震發生時，它能用筆在紙上記錄下
31 . records only the horizontal component of the wave movement,記錄下來的只是地震波運動中的水平部分，
32 . In the midst of all this movement, the weight and the pen would be still.重物和筆都卻不運動。
33 . With practice, no doubt, I could in time learn to write by holding the pen still while the paper moved.毫無疑問，經過練習，我最終能夠學會筆不動而紙動來寫字。
34 . That sounds a silly suggestion,這聽起來似乎是一種愚蠢的想法，
35 . If it were gentle, only the more unstable rods fell.如果地震輕微，只有不穩定的木棒倒下；
36 . But instruments far more delicate than that were needed if any really serious advance was to be made.但是，如果要取得真正重大的進展，需要有比這種裝置精細得多的儀器。
37 . A simple experiment will help us a little further.再做一個簡單的實驗可以幫助我們進一步理解這個問題。
38 . the graphic record shows three waves arriving one after the other at short intervals.曲線紀錄就能顯示出前後相間的這3種地震波。
39 . it would be more like that of a bluebottle buzzing round the room;那就像一隻嗡嗡叫的綠頭蒼蠅在屋內飛行的軌跡，
40 . its movement would be recorded in ink upon its surface.紙的表面就會用墨水記錄下地板運動的情況。
41 . It was necessary, therefore, to invent instruments that neither slumbered nor slept.因此，有必要發明一種儀器，既不打盹兒，也不睡覺。
42 . If we could actually see the path described by a particle,such as a sand grain in the rock,假如我們真能看到的運動軌跡，諸如岩石中一個沙粒分子
43 . The first records the arrival of longitudinal vibrations.首先記錄下的是縱向波的到達；
44 . It was from the study of these that so much was learnt about the interior of the earth.正是從這兩種波的研究中，我們可以瞭解到地球內部的許多情況。
45 . An earthquake comes like a thief in the night, without warning.地震就像夜間的小偷，不打招呼就來了。
46 . When the instrument is situated at more than 700 miles from the earthquake centre,如果把這種儀器安裝在距震源700多英里遠的地方，
47 . the movements of the ground or of the table as the quake passed by.大地和桌子的運動情況。
48 . When a shock came, it shook the rigid table upon which these stood.一旦有地震，就會震動豎立在堅硬的桌子上的木棒。
49 . But when table, penholder and paper are all moving, how is it possible to write legibly?可是，當桌子、夾筆裝置、紙都在移動時，怎麼能書寫得清楚呢？
50 . is the slowest and has travelled round the earth through the surface rocks.是最慢的，是圍繞地球通過表面岩石傳來的。