FOG-PIERCING LIGHT

Greymouth Evening Star, 23 June 1928, Page 2

FOG-PIERCING LIGHT

TO MAKE FLYING SAFE.

Fog is the most dreaded enemy of the flying man. He becomes lost in it, and is therefore in danger. A cloud is a “bunch of -fog” floating in the sky. A fog ordinarily is a cloud lying upon the surface of the earth, with clear sky above it. But sometimes there is a layer of cloud Ihigli up, with a clear space between it and the fog beneath. Climbing, to get out of the fog, the aviator is again lost in the mist far aloft. A dense fog so obscures the lights of landing fields that the airman may not be able to see them, and thus finds himself in a hazardous situation.

It has recently been discovered, says a correspondent of the “San Francisco Chronicle,’' that a. “neon” light possesses an extraordinary fog-piercing power, and such lights are now being tried out exeprimentaHy on some landing fields. They' are proving highly satisfactory. Neon is one of the rare gases in the atmosphere. Glass tubes filled with it, when an electric current is passed through them, give an orange-red light of great brilliancy. It is on this principle that the new fogpiercing lights are constructed. A neon beacon, on a landing field can, it is said, be seen from aloft even in the thickest fog at night. Use of this property of the gas in question is also made in the construction of many electrical signs for night advertising Their brilliance and vivid colour attract attention.

At a number of airports neon beacons are already in use. Such a beacon consists of a complex arrangement of glass tubes elevated as high as may be practicable on skeleton steel towers. A neon “grid” of glass tubes is an essential part of the apparatus used for “television.”

The atmosphere, roughly speaking, is four-fifths nitrogen and one-fifth oxygen. But it contains nearly one per cent of argon and minor percentages of four other rare gases—-helium, neon, krypton and xenon. For the last two no uses have been found. But helium (obtained from natural gas) is valuable for filling balloons, and argon is employed in incandescent electrical lamps. Next to argon, neon is the most plentiful of the five rare gases. In the atmosphere there is one part of it in, every 80,800 of air. Argon and neon are both obtained incidentally to the process of making liquid air. To liquefy air an extreme cold is required, and, inasmuch as argon and neon become liquids at different and somewhat higher temperatures, they are “separated out’’ in the course of the laboratory operation. It is thought that before long means will be found for separating the helium from air in the process of liquefying The latter If that is brought to pass, there will be no further necessity for getting helium from natural gas. It will be extracted from the atmosphere much more cheaply, and will be available in unlimited quantities for inflating dirigibles and* other heavler-than-air craft.