Smoke signals

Smoke signals are one of the oldest forms of communication.

Using puffs of smoke people could communicate from tower to tower up to 300 miles in just a few hours.

Although there were downsides to this such as weather conditions and lighting.

In a sense a developed format of smoke signals can be seen in a distress flare, this flare is used mainly at sea to alert someone. The flare itself shoots up and lights up the sky to show someones position.

following on from this a new idea could be using High intensity discharge lights, having some form of activator to start them and have them pulse or flash, The light from these Xenon bulbs is immensely bright and could be seen from a high distance.