【正文】 of a railway mail car. It was during the Age of the Iron Horse that delivery really started to pick up. In fact, the United States transported most bulk mail by train for nearly 100 years. The first airmail service didn39。t start until 1918.Please take a few moments to look around. I hope you39。ll enjoy your tour. And as you continue on your own, may I suggest you visit our impressive philatelic collection. Not only can you look at some of the more unusual stamps issues, but there is an interesting exhibit on how stamps are made.I063(woman) Most people think of astronomers as people who spend their time in cold observatories peering through telescopes every night. In fact, a typical astronomer spends most of his or her time analyzing data and may only be at the telescope a few weeks of the year. Some astronomers work on purely theoretical problems and never use a telescope at all.You might not know how rarely images are viewed directly through telescopes. The most mon way to observe the skies is to photograph them. The process is very simple. First, a photographic plate is coated with a lightsensitive material. The plate is positioned so that the image received by the telescope is recorded on it. Then the image can be developed, enlarged, and published so that many people can study it.Because most astronomical objects are very remote, the light we receive from them is rather feeble. But by using a telescope as a camera, long time exposures can be made. In this way, objects can be photographed that are a hundred times too faint to be seen by just looking through a telescope.I071(woman) Before we start our first lab, I39。d like to tell you a little bit about the workbook we39。ll be using.The first thing I39。d like to point out is that the workbook contains a very large amount of material far more than you could ever handle in a single semester. What you39。re supposed to do is choose the experiments and activities that you want to do within a certain framework, of course. Part of my job is to help you make your choices.Next, I39。d like to mention that in each workbook chapter, there are usually two subsections. The first is called Experiments and the second is called Activities.In the Experiments section, the workbook gives full instructions for all the experiments, including alternate procedures. Choose the procedure you wish there39。s plenty of equipment available. In the Activities section, you will find suggestions for projects that you can do on your own time. You39。ll see that there are usually no detailed instructions for the activities you39。re supposed to do them your own way.If there are no questions, let39。s turn to Chapter One now.I072(woman) Do you have trouble sleeping at night? Then maybe this is for you. When you worry about needing sleep and toss and turn trying to find a fortable position, you39。re probably only making matters worse. What happens when you do that, is that your heart rate actually increases, making it more difficult to relax.You may also have some bad habits that contribute to the problem. Do you rest frequently during the day? Do you get virtually no exercise, or do you exercise strenuously late in the day? Are you preoccupied with sleep, or do you sleep late on weekends? Any or all of these factors might be leading to your insomnia by disrupting your body39。s natural rhythm.What should you do, then, on those sleepless nights? Don39。t bother with sleeping pills. They can actually cause worse insomnia later. The best thing to do is drink milk or eat cheese or tuna fish. These are all rich in amino acids and help produce a neurotransmitter in the brain that induces sleep. This neurotransmitter will help you relax, and you39。ll be on your way to getting a good night39。s sleep.Until tomorrow39。s broadcast, this has been another in the series Hints for Good Health. I073(Man) Today we39。ll examine the role that private transportation namely, the automobile plays in city planning.A number of sociologists blame the automobile for the decline of the downtown areas of major cities. In the 195039。s and 196039。s the automobile made it possible to work in the city and yet live in the suburbs many miles away. Shopping patterns changed: instead of patronizing downtown stores, people in the suburbs went to large shopping malls outside the city and closer to home. Merchants in the city failed。 and their sores closed. Downtown shopping areas became deserted.In recent years there39。s been a rebirth of the downtown areas, as many suburbanites have moved back to the city. They39。ve done this, of course, to avoid highways clogged with muters from the suburbs.I39。ve chosen this particular city planning problem our dependence on private transportation to discuss in groups. I39。m hoping you all will e up with some innovative solutions. Oh, and don39。t approach the problem from a purely sociological perspective。 try to take into account environmental and economic issues as well.I081(woman) Word es from California of a new weapon in the war on household pests. Two scientists working for a firm in Anaheim, California, have developed a method to eliminate insects without using dangerous chemicals. The new poison? Hot air.The basic idea is that insects cannot adjust to temperatures much above normal. In laboratory experiments, cockroaches and termites can39。t survive much more than a quarter of an hour at 125 degrees Fahrenheit, or about 50 degrees centigrade. The new method involves covering a house with a huge tent and filling it with air heated to around 65 degrees centigrade. Hot air is forced in with fans, and the tent keeps the heat inside the house. Since termites try to escape by hiding in wooden beams, the heat treatment must be continued for a full six hours. But when it39。s all over, and the insects are dead, there are no toxic residues to endanger humans or pets, and no funny smell