Lesson 42 Recording an earthquake

In the midst of all this movement, the weight and the pen would be still.

重物和筆都卻不運(yùn)動。

Lesson 42 Recording an earthquake

But as the paper moved from side to side under the pen point,

由于紙?jiān)诠P尖下來回運(yùn)動，

Lesson 42 Recording an earthquake

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(yùn)動的情況。

Lesson 42 Recording an earthquake

It was upon this principle that the first instruments were made,

據(jù)這一原理，制造出了最初的地震儀器，

Lesson 42 Recording an earthquake

but the paper was wrapped round a drum which rotated slowly.

根但是紙是卷在慢慢旋轉(zhuǎn)的圓筒上的。

Lesson 42 Recording an earthquake

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；

Lesson 42 Recording an earthquake

but while the drum was being shaken,

但是，圓筒受到震動，

Lesson 42 Recording an earthquake

the line that the pen was drawing wriggled from side to side.

筆所畫出的線就會左右擺動。

Lesson 42 Recording an earthquake

The apparatus thus described, however,

然而，這里所說的儀器

Lesson 42 Recording an earthquake

records only the horizontal component of the wave movement,

記錄下來的只是地震波運(yùn)動中的水平部分，

Lesson 42 Recording an earthquake

which is, in fact, much more complicated.

地震波的運(yùn)動實(shí)際比這要復(fù)雜得多。

Lesson 42 Recording an earthquake

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(yùn)動軌跡，諸如巖石中一個沙粒分子

Lesson 42 Recording an earthquake

it would be more like that of a bluebottle buzzing round the room;

那就像一只嗡嗡叫的綠頭蒼蠅在屋內(nèi)飛行的軌跡，

Lesson 42 Recording an earthquake

it would be up and down, to and for and from side to side.

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。

Lesson 42 Recording an earthquake

Instruments have been devised and can be so placed that all three elements can be recorded in different graphs.

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繪出這三種運(yùn)動的曲線圖。

Lesson 42 Recording an earthquake

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(yuǎn)的地方，

Lesson 42 Recording an earthquake

the graphic record shows three waves arriving one after the other at short intervals.

曲線紀(jì)錄就能顯示出前后相間的這3種地震波。

Lesson 42 Recording an earthquake

The first records the arrival of longitudinal vibrations.

首先記錄下的是縱向波的到達(dá)；

Lesson 42 Recording an earthquake

The second marks the arrival of transverse vibrations which travel more slowly and arrive several minutes after the first.

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，在縱向波到達(dá)幾分鐘后才能到達(dá)。

Lesson 42 Recording an earthquake

These two have travelled through the earth.

這兩種波都是穿過地球而來的。

Lesson 42 Recording an earthquake

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，我們可以了解到地球內(nèi)部的許多情況。

Lesson 42 Recording an earthquake

The third, or main wave,

第三種波，即主波，

Lesson 42 Recording an earthquake

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巖石傳來的。

Lesson 43 Are there strangers in space

We must conclude from the work of those who have studied the origin of life,

我們必須從那些研究生命起源的人的工作總結(jié)出：

Lesson 43 Are there strangers in space

that given a planet only approximately like our own, life is almost certain to start.

如果設(shè)想有一顆行星和我們地球的情況基本相似，那幾乎肯定會產(chǎn)生生命。

Lesson 43 Are there strangers in space

Of all the planets in our own solar system,

在我們太陽系的所有行星中，

Lesson 43 Are there strangers in space

we are now pretty certain the Earth is the only one on which life can survive.

我們目前可以肯定的是，地球是生命能存在的唯一行星。

Lesson 43 Are there strangers in space

Mars is too dry and poor in oxygen, Venus far too hot, and so is Mercury,

火星太干燥又缺氧，金星太熱，水星也一樣。

Lesson 43 Are there strangers in space

and the outer planets have temperatures near absolute zero and hydrogen-dominated atmospheres.

除此以外，太陽系的其他行星的溫度都接近絕對零度，并圍繞著以氫氣為主的大氣層。

Lesson 43 Are there strangers in space

But other suns, stars as the astronomers call them, are bound to have planets like our own,

但是，其他的太陽，即天文學(xué)家所說的恒星，肯定會有像我們地球一樣的行星。