TOEFL Listening: ETS-TOEFL听力机经 - 4T4057B3F11ID8E2Q$

Lecture: Gorrie's refrigeration machine: Narrator: Listen to part of the lecture in a United States history class. Professor: Okay. You want to talk about a really significant invention? How about mechanical refrigeration and air conditioning? Think about it, our country would be a very different place without it. For example, how about the fact that hotter regions of the United States, oh ... like Florida would only have a fraction of the current populations, or that we probably wouldn't have many skyscrapers since you can't open the windows fifty stories up because of high winds, and an opened window was about the only way to cool a room in the past. And industrial applications of refrigerated air have been extremely important. Let's look at the printing industry, for example. Hm, paper expands and contracts according to the amount of moisture in the air. So before air conditioning, it could be impossible to align the inks for printing in color. So, even something as mundane as color magazines, something we take for granted. It's the regulation of temperature and humidity in the print shop that makes them possible. Now, it turns out making something cold is not so easy. I mean, to make something hotter, you can heat it with fire, for example. But to cool something? Sure, if it is winter you can get some ice and you're okay but how practical is that? And what if it isn't winter? Now, one of the guys who mulled over this problem was a Dr. John Gorrie. Dr. John Gorrie moved to Apalachichola, Florida in the 1830s. In those days, Florida, with its hot, humid summers, its snakes, alligators, mosquitoes, and its tropical diseases was a hard place to live. But Apalachichola was actually the second largest port in the Gulf of Mexico. Much of the cotton grown in southern US states, and that was a lot, was shipped out of Apalachichola. Now, in the 1840s, Dr. Gorrie, in deciding how to treat those tropical diseases, deduced that since they occurred in the summer, they must be in some way caused by the heat. The cure, therefore, would be to, in effect, change the season. Take summer and the heat of it away. We're lucky he drew that conclusion instead of the correct one, which is probably why he didn't go down in history for any great medical breakthroughs. Anyway, his first experiments with these treatments let him develop cold rooms, or rooms cooled with ice. In some case, the ice was in the ceiling. Gorrie understood, of course, the principle that cold air is heavier than hot air and that air cooled by the ice would fall down over the patients. In other cases, he had fans blowing over the ice. Nevertheless, the bigger problem, as you can imagine, was acquiring ice. There were ice companies at the time that sawed huge blocks of ice out of frozen lakes and shipped this ice all over the world. But keep in mind Florida isn't close to the northern United States. Ships filled with ice had to sail a long way and well, some ships would encounter storms or ice would melt, and what actually got there was very much in demand and subsequently, not cheap. You have to wonder, how much ice would be left, say, in August, since it had to be stored all summer in insulated warehouses. So, what do you think Gorrie did? Well, with his inclination for tinkering and his science background, he set out to invent an ice making machine. Just imagine! He took advantage of some very basic principles. The most important being this: air that is compressed, cooled and then allowed to re-expand gets very cold indeed. And that seems simple, but it's basically the principle all of our subsequent refrigeration technology is based on. Now, Gorrie's first attempt at a refrigeration machine was big and clumsy. It leaked and broke down a lot, but it did make ice. Unfortunately, although Dr. Gorrie did get a patent for his refrigeration machine in 1851, he never realy raised enough money to develop it. He blamed the ice industry for his problems. It's pretty clear that they didn't want to see his invention being perfected. Even worse, the media ridiculed his achievement. It's a shame too, because Gorrie was a visionary. He thought this invention could later be adapted to transporting perishable foods all over the country in all seasons, among other uses. It's unfortunate nobody took him seriously at the time.