HELIOGRAPH SIGNALLING.

New Zealand Herald, Volume LXVI, Issue 20241, 29 April 1929, Page 14

HELIOGRAPH SIGNALLING.

Sir,—l should like to give a tip to airmen and others which may prove useful some time or other: that is the use of a mirror as a flash signal. Of course, it must be a day with sunshine. The writer has on three different occasions called up assistance, one time from 20 miles away and with a piece of mirror not more than 6in. square. It is a known fact that heliograph signalling has been carried on in high altitudes at 90 miles or more between parties. If Kinesfcrd Smith had used this means he would have drawn attention long before he did. A mirror should be part of every airman's equipment, so if he is forced down he would save himself and others a lot of trouble and perhaps his life. It is quite a simple thing to do. Face the line in which one wants to signal, make the flash on the ground near you to see if it is in line, then move it up and down. An airman at 10,000 ft. would pick up the flash at a great distance. If there is no given spot to flash to then flash all round, which can be done if the sun is high. Even the inside of a watch lid, if bright, will be seen a mile or more. This is something: worth knowing and may bo very useful some day to any of us. Flash.