subject: Uses Of Balloons [print this page] Both free and captfve balloons have been useful to man. Captive balloons were used for military observation as early as 1794, during the French Revolution. Such balloons were also used during the American Civil War. Soldiers went up in their balloons and saw what the enemy was doing, then dropped messages to the ground. During World War I and II thousands of captive balloons were sent up over cities such as London. The balloons were connected to the ground by strong cables and had wires and cables hanging underneath them.
The purpose of this was to defend the cities against low-flying enemy fighter planes. The planes had to fly higher than the balloons, or else get caught in the wires and cables. When they flew high, they could not aim their bombs so well. These balloons were called barrage balloons. Free balloons were used during the French Revolution to drop small bombs. The balloons would be floated over enemy territory with a lighted fuse inside them, to explode the bombs when the balloon was over enemy territory. Sometimes the wind changed and the balloons were blown back and the bombs exploded over the people who sent them up. Free balloons are also used by scientists to examine the air miles above the ground.
These balloons are equipped with airtight metal balls, or gondolas, in which the scientists ride beneath the balloon balloon. The gondolas contain oxygen so that the scientists will be able to breathe when they are several miles high, where there is not much oxygen in the air. The scientists must wear heavy clothing because it is very cold high in the air. These balloons are very large and often go many miles into the air. When the balloons leave the ground they carry ballast.
This is a load of sandbags or other heavy stuff. When the men in a balloon want to rise higher they throw out some of the ballast. This makes the balloon and its load lighten, and causes it to go higher. When the scientists want to come down they let some gas out of the balloon by pulling a cord connected to a valve on top of the balloon. The balloons are made of specially treated cotton cloth or silk. They are often more than 30 feet across. One famous balloon called the Explorer II measured 192 feet across.
In 1935 two United States Army officers went up in the Explorer II and reached a height of almost 14 miles. Balloon races are held every year in England and the United States. The purpose of these races is to see which balloon can stay up in the air the longest and travel the farthest distance. Some balloons are sent high into the air without any men inside the gondola. These balloons are called weather, or sounding, balloons. They contain radio transmitters that send signals down to the ground, giving scientists information about the air above. Some balloons have gone more than 28 miles up. When it reaches a certain height, a sounding balloon explodes and the instruments inside are carried gently to the ground by parachutes
