Historical information

The Heliograph MkV is a fascinating piece of historical surveying and communications equipment. It was primarily used for visual signaling by reflecting sunlight with a mirror to send coded messages over long distances. This method was primarily useful in remote areas where other forms of communication were not available. The MkV model, specifically, was widely used by the British Army and other military forces from around 1906 until the mid 1960s. It remained in use with the Australian Army Survey Corps until the mid 1980s. The device typically included a 5 - inch mirror and was often mounted on a tripod for stability. Initially the instrument was used to communicate between survey stations using Morse code to coordinate their activities. Later when better forms of communication were available, they were used for precise angle alignment where the sunlight reflection from the mirror was targeted between the survey stations to give very accurate results. The MkV was relatively light weight and portable, making it ideal for use in the field. It could be setup and adjusted quickly. The heliograph had an adjustable mirror that could be tilted to reflect sunlight towards a distant receiver. Surveyors could align the mirror using a sighting device. Whilst it was primarily used by the Military it was also used in civil surveying particularly in the remote areas of Australia.
The British Army Mark V version uses a flat round mirror with a small unsilvered spot in the centre. The sender aligned the heliograph to the target by looking at the reflected target in the mirror and moving their head until the target was hidden by the unsilvered spot. Keeping their head still, they then adjusted the aiming rod so its cross wires bisected the target, they then turned up the sighting vane, which covered the cross wires with a diagram of a cross, and aligned the mirror with the tangent and elevation screws, so the small shadow that was a reflection of the unsilvered spot hole was on the cross target. This indicated that the sunbeam was pointing at the target.
If the sun was in front of the sender, its rays were reflected directly from this mirror to the receiving station. If the sun was behind the sender, the sighting rod was replaced by a second mirror, to capture the sunlight and direct it onto the main mirror to reflect it to the receiving station.

Physical description

. 1 Brish Army "Mance" Mk V A253 Heliograph has two 125mm diameter mirrors on a brass arm with targeting attachments. The Instrument is mounted on a three-legged tripod of brass and mahogany with spiked feet, approximately 1.2 metres high. The instrument was made by LUCO Art Metal Co Ltd, London in 1940.
.2 A military green metal carrying safety storage case with khaki shoulder strap.

Inscriptions & markings

A253 stamped on instrument