Smoke signals originated in ancient Greece, developed by a historian, Polybius, who created an alphabetical code that was transposed to numbers which could be translated into signals such as smoke signals. This particular code was knows as the Polybius square and was later used by the Japanese and the Germans in times of war. The Chinese also used smoke signals along the Great Wall of China, and this was one of the very purposes of the wall. Signals could travel from station to station along the wall.
Smoke signals are made by creating a fire and then using a blanket or cover to create puffs of smoke or designs in the smoke to relay certain messages to other tribesman who are a distance away. The messages are not complex, but they are usually specific to each tribe so that an enemy will not be able to interpret the message. There were, however, some standard messages, known to most tribes: one puff would mean "attention;" two puffs, "all's well"; and three puffs "danger." Smoke could be manipulated into spirals, circles, zigzags, and parallel lines, and the color of the smoke could even be changed somewhat by the wood that is burnt.
To aid in the transmission of a message over long distances, tribes would set up stations where fires could be built. These fire bowls were placed on hilltops where they could be easily seen, and a tribesman could send a message to one hilltop where another tribesman would see the message and build a fire to send a message to another hilltop, and so on. This could be used to warn of impending danger to the tribe or to gather a tribe together for a meeting. The fire bowls were designed to accommodate leaves and branches specific to that which were going to be burned and were lined with rocks and stones.
There is no indication as to when or why Native Americans stopped using smoke signals as a form of communication. It probably was phased out with the settlement of the Europeans and their written forms of communication. Today, though, the Boy Scouts of America continue to study and use smoke signals as a form of emergency communication when lost in the woods or in trouble. The signal is three puffs of smoke that hopefully would be able to be seen by his troop members from far away.