SLEUTHING. THE WORLD’S STORMS

Otago Witness, Issue 4033, 30 June 1931, Page 25

SLEUTHING. THE WORLD’S STORMS

AID FOR AIR PILOTS IN PERIL? HOW RADIO RULES THE WAVES (From a Correspondent.) LONDON, May 14. Radio may 50011 be used to trace the source of every thunderstorm in progress ■within two or three thousand miles of the observer. If this hope is realised aeroplane pilots will be able to steer their course to avoid one of their worst perils. Scientists at the Radio Research Station at Slough (about 20 miles from London), under the British Government Department of Scientific and Industrial Research, are now engaged on elaborate experiments to establish without doubt the reliability of their methods. They have invented one of the most sensitive and'remarkable pieces of apparatus that the wonders of wireless have yet produced. It is called a “ cathode ray direction-finder ” and it records, by the flickering of a little point of light, every important electrical disturbance that

goes on in any part of the earth’s atmosphere for thousands of miles around. This Slough station is the only place in the world where the instruments are made. They were invented by the superintendent, Mr Watson Watt. Two of them have just been supplied to the Australian Radio Board, where they are to be used for a new Australian stormtracking research scheme. A DETECTIVE FOR LIGHTNING. The apparatus lives in a little wooden hut which looks more like a chicken house than a laboratory. Here..hypersensitive apparatus reacts every t\me ’ there is a flash of lightning on a distant continent. The laboratory, a mass of wires and knobs, is plunged in daikness. Scientists bend over a little point of light, which is jumping about like a thing possessed. “ That looks like South Germany,” says the chief stormtracker. “ Nothing very much . . ah’ that an Atlantic disturbance, I should say, moving in. There’s something going on down Morocco way.” A kinema, which records every movement of the light, clicks away, making a-permanent record of far distant storms and depressions.

Each atmospheric lasts only about a five-hundredth of a second, and is recorded absolutely instantaneously. As many as 3000 signals a second may be received. HELP FOR THE AIR MAIL. But this only shows the direction of the storm. Scientists want to find its precise location on the map. So they have set up another exactly similar direction-finder in Scotland, about 400 miles away, with a land-line connecting the stations. Time signals are sent between the laboratories to synchronise the films exactly. One film is posted down from Scotland and the two are projected simultaneously on to a map of the world. Where two flashes cross is where that atmospheric originated. The scientists can now trace the source of a storm within two hours, while by their earlier methods it took four days. This time could be reduced to a few minutes if the Scottish instrument were arranged to transmit its indications over the land line by a simple method, already worked out, which is allied to picture transmission. This might make all the difference to aircraft, which depend on such observations to keep out of disturbed areas, and should also be of

great value in weather forecasts for ships, farmers and holiday-makers. These, of course, are practical applications of the new method of direction finding. Still more important, experts believe, is the theoretical question of “ What, why, and how is an atmospheric?” They have discovered that all atmospherics are due to electrical discharges or lightning. The Slough station’s object is to study the pure physics and higher of radio so as to provide“a background of knowledge on which the radio engineer can base his improvements. WHY WAVES GO WRONG. “ The practical side of wireless,” 1 was told, “ has outstripped the theoretical. Wireless waves do certain things, but often radio engineers don’t know why. This may lead to unforseen trouble, and the big advances of the future are likely to come only after more is known about the fundamental behaviour of waves.”

These scientists can sort out the millions of waves which crowd the ether, travelling at 180,000 miles per second, as easily as we can distinguish different types of cars in a stream of traffic. One fascinating field of study’ is called

“ wave propagation,” which means the adventures which befall a wave as it travels. When a signal is sent off, scientists explained, the impulse travels by different routes. One set of waves goes rtlong the ground, and this is picked up by broadcast receiving sets over short distances, and by ships. The other, however, goes u-pward and is reflected down again from the 'upper atmosphere, somewhat as light is reflected from a mirror. “NIGHT ERROR” AT SE2» Many radio troubles are caused by these two waves not joining up again exactly in step. When the peak of one wave coincides with the trough of another, you get what scientists c; II a “ fringe,” and “ fading,” familiar to listeners, results. These fringes have actually been photographed, and two distinct waves can be seen intermingling. “Night error” in direction-finding at sea is caused by these downcoming waves. It is often found, when taking wireless bearings, that direction-finders are 30 or 40, or even more, degrees cut at night. British scientists have perfected a new type of direction-finder which Joes not pick up the parts of the wave causing these troubles and which thuseliminates the error. For longer distance signals, such as those between Empire stations, the “ downcoming ” wave is the important one. Scientists are studying how it is reflected from the upper atmosphere, called the “ Heaviside ” layer after a man of that name who first suggested that such a conducting layer was needed to explain the success of radio communication. For years this remained a hypothesis. and it is only within the last 10 years that definite proof of the existence of the layer was. obtained by scientists working for the British Radio Research Board. Heaviside, then an old man, was, offered a medal for his original work, but refused it because by that time he was more interested in roses than in radio. MESSAGES TO MARS? These layers (for the same workers have shown that there are at least two of them, at about 00 and 120 miles above the earth’s surface) consist of electrons. Short-waves travel further through them before getting reflected back than do long waves. There comes a point, scientists believe, when very short waves go right through the layer and on into space. “ If there were any radio communication with Mars.” a scientist said to me, “ that is how it would be done.” At Slough they are trying to And out— this object—the shortest wave which can be sent without getting lost. They believe it may lie somewhere between the ranges of 5 and 10 metres. Wireless “echoes” are another problem. An echo is caused by the wave going right round the world and being picked up on the second lap, coming from behind. Apparatus has been designed that will not pick up these backdoor waves.

SPLIT SECONDS. The almost incredible accuracy needed for work on this “wave propagation'* is such that scientists can measure an effect produced by a time difference of a few millionths of a second. They study the angle at which an invisible wave hits an inaccessible layer, made up of theoretical particles, as happily as- if they were working out a new stroke in squash-rackets. The last Imperial Conference stressed the fact that the Empire’s progress depends largely on the efficiency of imperial communications. Wireless has become one of the most vital of these. The Empire must be linked in the ether as well as by.sea and air. That is why the British Government is supporting a research .centre where it is encouraging the British genius for invention to extract the fundamental secrets of radio out of the immense mysteries of space.