All About Ballons

balloons and airships You have seen rubber balloons filled with gas

, instead of being blown up with air. Men sell them in parks and at fairs. If you let go of the string attached to the balloon, it will quickly rise into the air and you will lose it. That is because the gas in the balloon is lighter than air. This makes the whole balloon lighter than the air around it, and it floats in the air. The balloon would also rise if it were filled with hot air, because warm air is lighter than cool air. In exactly the same way, a cork floats on water because it is lighter than water. Just as a little, light balloon will float with gas or warm air in it, a big, heavy balloon will float-if it has enough gas or warm air in it to make the whole thing lighter than the air around it. This was first discovered 150 years ago. Men knew that smoke rises. Smoke is a kind of warm air. It rises in the heavier cool air around it. One day two brothers named Montgolfier, who lived in France, decided to find out if a bag filled with smoke would rise into the air. They placed some burning charcoal near the opening of a large linen bag about 18 feet wide, and filled the bag with smoke. The bag began to rise into the air until it reached a height of 8 1/2 miles. The bag remained in the air for ten minutes. When the smoke began to cool, the bag slowly came down to the ground. This was in June, 1783. In August, 1783, a French scientist named Jacques Charles discovered that air is 14 times heavier than hydrogen gas. He decided to fill a balloon with hydrogen instead of smoke. He took a large silk bag, which held so much hydrogen that it took him four days to fill it. Thousands of people gathered in Paris to watch the balloon rise. When the balloon was filled, it was released by cutting ropes attached to bags of sand hanging underneath the balloon. These bags had held the balloon down until the ropes were cut. Charles' balloon rose high into the air. Forty-five minutes later it landed in a field fifteen miles away. To the workers in the field, the balloon looked like a monster from another world. They were so frightened that they ran to the balloon and immediately tore it to pieces. They were so afraid that it might kill them that they did not see it was just a balloon filled with gas. A month later a sheep, a rooster and a duck were placed in a basket attached by ropes to the bottom of another balloon. This balloon was then filled with hydrogen and rose into the air carrying the basket of animals. Such a basket or car attached to a balloon is called a gondola The animals were not hurt, so in October, 1783, another Frenchman, named de Rozier, went up in the basket himself. This time the balloon was filled with hot air, because hydrogen was still hard to get. The balloon was also connected to the ground by long guide ropes to keep it from floating away. Such a balloon is called a captive balloon. Balloons not connected to the ground are called free balloons. De Rozier was the first man to go up in a balloon. Shortly after, he was killed when a balloon he was in exploded. He was trying to go from France to England across the English Channel. The place where he crashed is marked by a monument to his memory. The gases most used in balloons are hydrogen, helium, and illuminating gas. Hydrogen is the lightest. Helium is scarce and very expensive, but it has one great advantage that hydrogen and illuminating gas do not have-it will not burn. Helium is used in all dirigibles in the United States. Because illuminating gas is so cheap, it is used in most free balloons.

All About Ballons

By: David Bunch

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