Smoke signals have been around for a very long time. They were first created by the Native North Americans and the Chinese. The Chinese used smoke signals along the Great Wall of China. The North American natives used smoke signals between camps.
Smoke signals are a form of optical telegraph. In other words, these messages can be sent over distances as long as you can see each signal. Smoke signals are sent by placing a cover (such as a blanket) over an open fire. After you make the fire, you can create a lot of smoke by adding handfuls of grass or green branches. By quickly lifting the cover for a short time, a puff of smoke will be sent up into the air. With training, a person can learn to control the puffs. People can learn to control the size, shapes, and time between puffs.
What is very important is that everyone sending and receiving the smoke signals must know what they mean. A code needs to be worked out so that everyone can understand the messages being sent. For example, four small puffs in a row might mean that an enemy is approaching. Two large puffs might mean that a friend is coming. Because only the senders and receivers know the code, smoke signals can be used to send secret messages.
While most smoke signals are secret, there are some standardized signals that are understood by many people around the world. For example, one puff means ATTENTION, two puffs means ALL'S WELL, and three puffs of smoke means DANGER OR TROUBLE.
Where you locate your fire is also very important. The 'sending station' should be on a high place that is visible to another high place (such as a mountain top). Then you can create a chain of sending stations that can be seen for miles. Long ago, there were stone signal towers along the coast of Greece, Turkey, and other Mediterranean sites.
Other things to think about include being able to create enough smoke to be seen by the next sending station, what will be done on windy days, and how do you make sure that the fire doesn't spread.
Conway, Emmett. "Smoke Signal Bowls - The First WWW." The Olde Forester. 3 November 2004 <http://www.oldeforester.com/sigbo.html>.
"Smoke Signals." Wikipedia, the Free Encyclopedia. 7 February 2005 <http://en.wikipedia.org/wiki/Smoke_signals>.
Tomkins, William. "Smoke Signals." The Inquiry Net. 7 February 2005 <http://www.inquiry.net/outdoor/native/sign/smoke-signal.htm>.
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