Native Americans used to smoke signals to send messages

      Native Americans threw wet grass onto a fire to produce thick clouds of smoke, and then covered the fire with a blanket. They then released the smoke that collected under the blanket at intervals to produce sequences of puffs of smoke that rose into the sky and were visible from a distance. However, this was not based on anything like a kind of Morse code. The meaning of the smoke signals was agreed in advance. This kind of long distance communication has been known since antiquity, and variations use torches instead of smoke.