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Until men invented ways of staying underwater for more than a few minutes, the wonders of the world below the surface of the sea were almost unknown. The main problem, of course, lies in air. How could air be provided to swimmers below the surface’ of the sea Pictures made about 2,900 years ago in Asia show men swimming under the surface with air bags tied to their bodies. A pipe from the bag carried air into the swimmer’s mouth. But little progress was achieved in the invention of diving devices until about 1490, when the famous Italian painter, Leonardo da Vinci, designed a complete diving suit.In 1680, an Italian professor invented a large air bag with a glass window to be worn over the diver’s head. To "clean" the air a breathing pipe went from. the air bag, through another bag to remove moisture, and then again to the large air bag. The plan did not work, but it gave later inventors the idea of moving air around in diving devices.In 1819, a German, Augustus Siebe, developed a way of forcing air into the head-cover-ing by a machine operated above the water. At last in 1837, he invented the "hard-hat suit" which was to be used for nearly a century. It had a metal covering for the head an air pipe attached to a machine above the water. It also had small openings to remove unwanted air. But there were two dangers to the diver inside the "hard-hat suit". One was the sudden rise to the surface, caused by a too great supply of air. The other was the crushing of the body, caused by a sudden diving into deep water. The sudden rise to the surface could kill the diver; a sudden dive could force his body up into the helmet, which could also result in death.Gradually the "hard-hat suit" was improved so that the diver could be given a constant supply of air. The diver could then move around under the ocean without worrying about the air supply.During the 1940s diving underwater without a special suit became popular. Instead, divers used a breathing device and a small covering made of rubber and glass over parts of the face. To improve the swimmer’s speed another new invention was used: a piece of rubber beathing pipes made it possible for divers to float on the water, observing the marine life underneath them. A special rubber suit enabled them to be in cold water for long periods, collecting specimens of animal and vegetable life that had never been obtained in the past.The most important advance, however, was the invention of a self-contained underwater breathing apparatus, which is called a "scuba".Invented by two Frenchmen, Jacques Cousteau and Emile Gagngn, the scuba consists of a mouthpiece joined to one or two tanks of compressed air which are attached to the diver’s back. The scuba makes it possible for a diver-scientist to work 200 feet underwater or even deeper for several hours. As a result, scientists can now move around freely at great depths, learning a- bout the wonders of the sea. In 1490 or so, the main progress mentioned in this passage was ().
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Anything, if it concerns all nations in the world, we need standards to regulatate it.Space flight and air travel would shock time travelers from the mid-19th century. People considered such thing impossible back again: But when it comes to that gem of late 20th century technology, the Internet, the time travelers might well say:" Been there. Done that."They have the masons to say so.Both system grew out of the cutting-edge science of their time. The telegraph’s land lines, underwater cables, and clicking things reflected the 19th century’s research in electromagnet- ism. The Internet’s computers and high-speed connections reflect 20th century, and material technology.But, while small devices make a global network possible, it takes human cooperation to make it happen. To do so, nations negotiated these standards through ITU—the International Telegraph Union—a century and a half ago.Consider a couple of technical parallels. Telegrams were sent from one station to the next, where they were received and retransmitted until they reached their destination. Stations along the way were owned by different entities, including national governments. Internet date is sent from one serve computer to another that receives and retransmits it until it reaches its destination. Again the computers have a variety of owners. Telegraph messages were encoded in dots and dashes. Internet date is encoded in ones and zeros.Then there’s the social impact. The Internet is changing the way we do business and communicate. It makes possible virtual communities for individuals scattered around the planet who share mutual interests. Yet important as this may turn out to be, it is affecting a world that was already well connected by radio, television, and other telecommunications. The Associated Press, Reuters, and other news services would have spread the bombing of Yugoslavia quickly without the Internet. In this respect, the global telegraph network was truly revolutionary. The unprecedented availability of global news in real time gave birth to the Associated Press and Reuters news services. It gave a global perspective to newspapers that had focused on local affairs. A provincialism that geographical isolation had forced on people for millennia was gone forever.As the experience of the past century and a half has shown, the standards set up by ITU are not only necessary, but also workable. Therefore, in today’s world, while the Internet is playing an ever more important role in our life, we also need standards, and that is through the same ITU—now called the International Telecommunication Union. The mid-19th century time travelers would not be surprised by today’s Internet because ().
W: Hey! you got a new television. M: Yeah, it was delivered yesterday. What do you think of it W: It’s huge. It practically takes up the entire side of the room. M: I know, I know. You don’t think it’s well, excessive, do you W: I didn’t say that. I mean, if you enjoy it, why not What happened to your old TV anyhow M: It just stopped working last Friday. It was pretty old and didn’t work well. I thought I can afford it, why net get a new one W: It must have been expensive. M: Well, not as much as you might think. I got it on sale for 50% off. W: Really Where M: At the stero city on Route 20. You know, at first I just want to replace what I had, a TV of about the same size and quality, but the salesman was pushing this because of the 50% off. W: Yeah, but 50% of what. M: 2,400 dollars. W: You spent 1,200 dollars on a TV M: It’s got a lot of special features. Look at this remote control. W: I’m sure, but that’s still a lot of money for a television. I don’t think you watch TV that much. M: Well, I don’t. Do you think I ought to return it If I do within a week of purchase, I can get my money back. W: Honestily yes! And you know what I think you should read up on TVs first, choose the make and model you want before you go to the store. That way you’ll get what you want. M: I think you’re right. What does the woman suggest the man do()
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W: That’s very exciting, of course, Mr. Jones. When did you see the UFO M: It was last Thursday. Much have been ten past six, give or take a minute or two, because I was just passing the post office after walking my dog. Every evening we take the same walk at the same time after retirement. W: Did you hear any noise M: Well, I did hear a faint buzzing noise. At first I though it was a plane. But it couldn’t possibly be, because it was Standing virtually still, and what’s more, it had no wings or engines or anything of that sort. W: But didn’t it move at all M: Yes, but it was when it suddenly rose up and streaked away up into the clouds with a mar and a rush of hot air. W: How big was it M: Oh, that’s something that struck me most. It was colossal. You know how small airliners look when they are in the air — they seem to be only a fraction of their real size. Well, this object looked about the size of a large airliner, even at that height. So if it were on the ground it would be enormous. W: Certainly, Mr. Jones. You’ve been flying for so many years. M: And can you imagine the engine power that would be needed to keep a thing that size in the air Incredible. Simply incredible. W: Certainly it is. Thank you, Mr. Jones. Today’s interview will appear on City Evening tomorrow. The object ().
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