PICTURES BY RADIO

Bay of Plenty Beacon, Volume 10, Issue 75, 20 January 1947, Page 6

PICTURES BY RADIO

ENGLAND TO AUSTRALIA SIX MINUTES IN TRANSMISSION Just after the all-clear had gone in London one night in 1941, a curious noise sounded through the corridors of the Thames Embankment headquarters of Cable and Wireless, writes Michael Marney, in the Strand Magazine. It was not a wail and it was not a whine. Some describe it as a blend of the two.

v It was the sound of a picture tra.velling through space from London to Australia.

The chairman, Sir E. Wilshaw, recognised the sound with a thrill of satisfaction. A member of the staff rushed into his room. “We’ve got it going again sir! Started sending the first picture at nine fifty-four. Transmission completed at ten o’clock.” The high-pitched note that he had heard was the noise made when an ordinary photograph is transmitted to any of the thirteen distant parts of the earth equipped to receive it. Earlier, every bit of picturegram apparatus in London had been destroyed by enemy action. Catastrophe seemed to have overtaken the service. Hard thinking had to be done. In the three months that followed it was possible to get the service going again. picturegrams are sent between London and five Empire cities, as well as six foreign capitals. The possibilities of the system are many and varied. For newspaper editors it has the excitement of a windfall. For international crooks it may be a considerable embarrassment.

A Press photographer’s shot' in Montreal can be on the desk of a London news editor in less than an hour of the event taking place. Allowing twenty minutes for highspeed shooting, developing, and printing at the Montreal end, six minutes for transmission, a further fifteen minutes for developing and printing at the London fend and another five minutes for delivery by messenger to the editor’s desk, we get a total of forty-six minutes. It means that you can see pictures of events on the other side of the world three-quarters of an hour after they have happened. The picturegram has already netted its first criminal. Scotland Yard had him identified in Australia. It was quite simple: “the Yard” sent a picturegram of his dossier, including his photograph and fingerprints. Secrets of the transmission system are a combination of the photoelectric cell, wireless, photography, and perfect timing. If the Editor of a magazine wishes to send a photograph for reproduction in, say, Australia, he has a print delivered to the Headquarters of Cables and Wireless, Ltd. There the print is handed to the picturegram operator, who clips it on a drum about the size of a small rolling pin. This drum is then made to revolve. As it does so a ray of light travels across it.

The best type of photograph for transmission is one taken at the correct exposure and given full development in the photographer’s dark room. That is, a picture with sharp contrasts.

Such a picture would be excellent for reproduction in a magazine or newspaper. The sharp contrasts prevent fogged outlines of figures or objects in the published picture, and help the picturegram transmission machine by reflecting light varying greatly in intensity on to a photolectric cell. The photo-electric cell changes the varying rays of light into electric waves.

Here wireless takes over. And the high-pitched note on the second floor of the Embankment building is heard as the waves go out to their destination, in'our example, Australia. But the picture cannot be seen there yet.

At the Australian end, three things happen very quickly. First, the electric waves change back into the original varying rays of light. Next, these rays, like those entering the lens of an ordinary camera, are directed on to a film clipped on a revolving drum. This revolving drum in Australia is similar to the transmitting drum in England. And here is the top secret of the system’s success. The two drums, 10,000 miles apart, are revolving at exactly the same speed. Perfect timing—that is the clue. Once the receiving drum has got the picturegram on its film, the rest is a simple dark-room operation. The film is developed in the normal way, and any number of prints can be made.

Newspaper offices, in conjunction with the General Post Office, operate another system of picture transmission known as telephotography. This requires a telephone circuit instead of wireless. Telephotography

ensures rapid transmission of photographs direct to newspaper offices, but its range is, restricted. For transmission over thousands of miles the picturegram is used. The first commercial picturegram service was opened in 1926. Progress made just before the war helped to treble the speed of transmission. One hundred pictures handled a month was the top score during the summer of 1939. During the last year of hostilities the number averaged 2000 a month.

At the end of 1945 the picturegram was further developed. In December the first full-colour halftone picture was telegraphed to Melbourne.

First, the photograph was broken down into its four-colour elements—yellow, red, blue and black. These four-colour elements, as black prints were transmitted to Melbourne, where a process engraver made his colour blocks from the four prints. From these a Melbourne printer produced the complete picture in colour. As soon as the equipment is available, picturegram apparatus will be installed at all important telegraph stations the world over. The Imperial network of 355,000 miles is operated through two hundred stations in seventy Empire and foreign countries.