The heliograph is a mirror set on a metal base which allows the mirror to be positioned on such a way as to reflect sunlight to a particular site. When operating over a long distance a telescope is used to assist in receiving the signals. The mirror can then be moved, by the use of a key to send flashes of light, therefore enabling the user to send a series of dots and dashes, in a code. The code used is known as Morse Code. The mirror and metal base are attached to a heavy tripod. This tripod has to be solid enough to hold the heliograph firmly in position, because moving the mirror slightly will take it off the aimed position. There are various components to be used with the helio, as there would be a required skill in setting it up, and being able to aim it correctly. Shown here it is prepared to operate with the sunlight behind it. Another mirror is set in a position to reflect sunlight onto the operating mirror.

Australian Light Horse made good use of the helio in the Desert campaigns in WW1, but they were aware of the drawbacks of the device. In open desert conditions it was a very useful item, but using it required the operator to be in a position where he could be seen, an obvious danger in warfare, and with sunlight unavailable the helio would not function.