How SCIENCE has shrunk the EMPIRE

Radio Record, Volume V, Issue 35, 11 March 1932, Page 1

How SCIENCE has shrunk the

EMPIRE

A small boy walked into a red telephone kiosk at the Imperial Institute, London, and said, "Hello, New Zealand,’ into the réceiver. New Zealand answered. That is one of the thrills that attracted thousands of children, of all ages from five up to 50, and over, to the Young People’s T elephone Exhibition, held recently in London.

(By

our London Correspondent

oe display shows them one of the greatest of modern miracleshow science has shrunk the Empire. Once inside the telephone box Auckland is no further off than South Kensington Underground Station.

At intervals, a spotlight is turned on to the milling crowd of children. The youngster on whom it falls is. picked out and led into the kiosk to telephone to some distant country-or maybe to a ship at sea. Concealed amplifiers broadcast both sides of the conversation to the excited crowd of fellow-children outside. This stunt was the star turn of London children’s Christmas holidays. The British Post Office has laid itself out to explain, in this exhibition, ‘How it’s done." The display tells the story of "speed in speech"-of how man has conquered distance in communication with his fellows. The small boy who talks to Australia, or any other overseas country, has only got to cross the hall to see a model of Rugby, the most powerful wireless transmitting station in the world, where his faltering voice was turned into waves which travelled 12,000 miles across the world. ‘This small boy is also given a glimpse of what happens to his telephone call at the exchange. He can watch it flicking through the complex mechanism of an automatic exchange without any human help.

At present, overseas calls go through the ordinary exchanges, but @ special overseas switchboard is nearing completion at the General Pos#. Office, which will handle all these calls, and which is, it is officially, stated, the most up-to-date and efficient in the world. Next door is a working model of an ultra-short-wave wireless telephony set, sig in the experimental stage. It works on a wavelength of 2 to 5 metres. .

Woes spoken into an ordinary telephong at one end of the stand come out throught a loudspeaker at the other end-having been transmitted on a two of, three-metre wavelength. In another part of the hall you can talk into a telephone to a listener one yard away-and your voice travels 1000. miles between the two instruments. The line goes up to Glasgow and back. Post Office engineers have devoted a stand to telling you how this is made possible. A model illustrates graphically how a speech

impulse travels in waves, like 4 ripple on the water. These: get fainter and fainter as the voice cone tinues on its journey. They would. fade out altogether were it not fof loading coils, which are put in ag intervals to re-energise the impulse, There are seven "repeaters," on ree energising stations, between Londort and Edinburgh, for instance, and 2%, between London and Berlin. Some people have good teles phone voices and some bad. It all depends on the number of "hare monics" in a voice. If you have a lot, the reception is bad because hare monics cannot be transmitted over ordinary telephone lines. A voice with the harmonics cut out loses alk its character and tone. This is one of the big problems of establishing (Concluded on page 2.)

Empire Radio (Continued from page 1.) relay stations for broadcasting. A relay’ line built for the British Broadcasting Corporation, for instance, cost £500,000 because of the elaborate devices for | transmitting every range and gradation of sound-including even the: shrill note of the piccolo. What is the shape of your voice? Is it angular or curved? Jagged or jumpy? Visitors are able to see their own voices at the exhibition. The voice appears as a wriggling, jumping beam of blue light. Bach voice looks different. A shrill note makes the beam shimmy feverishly. A deep bark results in big, sudden jumps. This effect is obtained by speaking into an ordinary receiver attached to a cathode ray oscillograph. The beam of blue light is thrown on the end of the valve and is deflected by the impulse of the voice. This beam dances about, forming different shapes according to the strength and _ frequency of the voice. The latest invention in telegraphy is attracting crowds of eager children. This is the teleprinter. This instrument looks like an ordin‘ary typewriter with a standard keyboard. The operator simply types the message and it is simultaneously reproduced, at the rate of 360 characters a minute, on a distant typewriter at, say, Glasgow or Plymouth. It appears without human intervention, as a typewritten strip which is pasted on to the telegraph form. YTeleprinters were originally invented by a Glasgow post office mechanic called Creed. Now they are rapidly superseding all other instruments used for sending telegrams. The post office looks. forward to the day when businessmen will have teleprinters in the office, and will send instantaneous messages direct to other private individuals. For business dealings this would have one important advantage over the telephone-the order would be in writing and the possibility of misunderstanding would thus be wiped out. The biggest crowds of children are clustering round two other new inventions. One is a model telephone kiosk which lights up when the daylight fades-or when a hand is placed over a window in the roof. It is fitted with a selenium cell (the active principle behind the talkies and picture transmission), which turns on a switch when it

is deprived of light. Phone boxes of the future may, if the experiment is put into practice, light up automatically as it gets dark. The other is a new fire alarm. It registers its own number and position at the fire brigade’s headquarters when the handle is pulled. It also rings a loud bell when it is touched in the vital spot to attract the attention of passersby, and so discourage small boys who amuse themselves: by giving false alarms.