SIGNALLISING BY MIRRORS.

Kumara Times, Issue 847, 18 June 1879, Page 4

SIGNALLISING BY MIRRORS.

The lasi mall from South Africa brought the news that communication had been established between Ekowe and Fort Tenedos by means of mirrors, and in the Times of 2nd April Mr E. 3. Brewer drew attention to the fact that very successful experiments in mirror telegraphy have been carried out in New South Wales, under the supervision of Lieutenant Parrott, of the Volunteer Engineer Corps of that colony. The idea is no new one. For centuries the rays of the sun have been utilised for signalising purposes. It is said that the fleet of Alexander the Great was guided along the Persian Gulf by means of mirrors. The North American Indians on the prairies carry on signalling by sun flashes, and. the Russians adopted a similar method at the siege of Sebastopol. In this climate where the sunlight is capricous, such a system could not be relied on; but in more tropical climates its utility is obvious. Even in England, however, Colonal Colley, R.E., and Captain Drummond, of the same corps, designed an instrument called the heliostat, which consisted of an adjustable mirror worked in connection with a combination of telescopes. By its means triangles with sides over 100 miles in length wCre : accurately laid down in the Ordnance Survey of the United Kingdom. The heliostat, however, did not admit of a conversation being carried on. The Mance heliograph is an apparatus designed for the transmission by reflection of the sun’s rays. The signals made by it are visible, under favorable conditions of position and atmosphere, practically to an unlimited distance, and have been read as far as 80 or 100 miles. It consists of a specially-prepared mirror, with ingeniously constructed mechanism for reflecting the sun’s rays with absolute precision to any required spot, notwithstanding the sun’s apparent movement. By the pressure of a finger key the flashes are made of short or long duration, thus adapting the the instrument to the Mosse code of telegraphy. A second instrument is provided to permit of signalling being carried on irrespective of the sun’s position. The instrument intended for field service weighs from 61bs to 81ba, and is mounted on a light tripod stand. The working parts are protected from injury during transit, and the complete apparatus admits of being easily earned, as it is also officially worked, by one man. Although the heliograph can never supersede either the electric wire or the flag, it can be used in situations where neither of these would avail, and consequently it may be looked on as an invaluable adjunct to modern military equipment.