新概念第四册课文翻译及学习笔记：Lesson42【课文】First listen and then answer the following question.听录音，然后回答以下问题。What does a pen have to do to recordon paper the vibrations generated by an earthquake?An earthquakecomes 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. Ifit were severe, they all fell. Thus the rods, by falling, and by thedirection in which they fell, recorded for the slumbering scientistthe strength of a shock that was too weak to waken him, and thedirection from which it came.But instruments far more deliecatethan 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 layin 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 stringso 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 firstinstruments were made, but the paper was wrapped round a drum which rotated slowly. As long as all was still, the pen drew a straightline, but while the drum was being shaken, the line that the pen wasdrawing 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 seethe 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 aparticle, such as a sand grain in the rock, it would be more likethat 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 andcan be so placed that all three elements can be recorded in differentgraphs.When the instrument is situated at more than 700 milesfrom the earthquake centre, the graphic record shows three wavesarriving one after the other at short intervals. The first recordsthe arrival of longitudinal vibrations. The second marks the arrivalof transverse vibrations which travel more slowly and arrive severalminutes after the first. These two have travelled through the earth.It was from the study of these that so much was learnt about theinterior of the earth. The third, or main wave, is the slowest andhas travelled round the earth through the surface rocks.H.H,SWINNERTON The Earth beneath Us【New words and expressions生词和短语】earthquake n.地震slumber v.睡眠ninepin n.九柱戏中的木柱rigid adj.坚硬的delicate adj.灵感的seismometer n.地震仪penholder n.笔杆legibly adv.字迹清楚地drum n. 鼓状物wriggle v.扭动bluebottle n.绿头苍蝇graph n.图表graphic adj.图示的longitudinal adj.纵向的transverse adj.横向的【课文注释】1.slumber v.睡眠例句： She fell into restful slumber.她进入宁静的安眠之中。Allow no sleep to your eyes, no slumber to your eyelids.不要容你的眼睛睡觉，不要容你的眼皮打盹。【词义辨析】sleep, doze,nap, slumber这些动词均含“睡”之意。sleep :普通用词，指一般的睡眠。可用作引申指长眠或静止不动。doze :多用于口语中，指轻微的小睡或处于半睡状态。nap :指白天的小睡。slumber :多指人安详地或长时间地睡。2. stand up on end竖立着3.rigid adj.坚硬的; 刻板的例句： The tent has a rigid support.帐篷有一个坚硬的支柱。Hes very rigid in his ideas.他的想法非常固执。【词义辨析】rigid, strict, rigorous这些形容词均含“刻板的，严格的”之意。rigid: