The firing of signal guns was telegraphing by sound. It used only the
hearing. But there were other ways of telegraphing that used the sight.
These have been known for thousands of years. They were known even to
savage people.
The Indians on the plains use fires to telegraph to one another.
Sometimes they build one fire, sometimes they build many. When a war
party, coming back from battle, builds five fires on a hill, the
Indians who see it know that the party has killed five enemies.
But the Indians have also what are known as smoke signals. An Indian
who wishes to send a message to a party of his friends a long way off,
builds a fire. When it blazes, he throws an armful of green grass on
it. This causes the fire to send up a stream of white smoke hundreds of
feet high, which can be seen fifty miles away in clear weather. Among
the Apaches, one column of smoke is to call attention; two columns say,
"All is well, and we are going to remain in this camp;" three columns
or more are a sign of danger, and ask for help.
[Illustration: A Smoke Signal.]
Sometimes longer messages are sent. After building a fire and putting
green grass upon it, the Indian spread his blanket over it. He holds
down the edges, to shut the smoke in. After a few moments he takes his
blanket off; and when he does this, a great puff of smoke, like a
balloon, shoots up into the air. This the Indian does over and over.
One puff of smoke chases another upward. By the number of these puffs,
and the length of the spaces between them, he makes his meaning
understood by his friends many miles away.
At night the Indians smear their arrows with something that will burn
easily. One of them draws his bow. Just as he is about to let his arrow
fly, another one touches it with fire. The arrow blazes as it shoots
through the air, like a fiery dragon fly. One burning arrow follows
another; and those who see them read these telegraph signals, and know
what is meant.