Looking back at old technology it is often hard for us to get a sense of the behind-the-scenes infrastructure which was needed to support these important products. It is also difficult for us to grasp how quickly those infrastructures were forced to grow to keep up with consumer demand. While we are still surrounded today by many of the consumer facing artefacts (such as old telephones, radios, televisions and computers) the background infrastructures created at the time for them to work are usually long gone.
I’ve read before about how the Telephone networks of the earlier 20th Century were becoming overcrowded and how this ultimately inspired clever (and probably stressed) Engineers around the world to think up new ways to use the existing lines more efficiently. Such facts are of course interesting, but for me a picture can often be more effective than simple words. Recently I was grateful to stumble across an article about the UK Telephone Network in the ‘Practical Electrical Engineering’ Magazine of 1931 which had such images.
The pictures below are taken from that article and the two contrasting cross sections of wire from the London to Liverpool route are particularly stark. These show that they required a seven fold increase of lines per cable in just 17 years. If you then relate that to the image of the cable duct trench photograph being dug, this shows over 126 cable tubes (yes I counted). If one cable of 352 pairs was placed in each tube, that trench alone would be able to carry nearly 45,000 telephone calls. Since you can’t just go on burying more and more cables forever, it is no-wonder telephone engineers gave a sigh of relief when more modern technologies such as PCM, Fibre-Optic and Satellites finally came along!
All images taken from: ‘Telephone Engineering’ by TE Herbert in Newnes Practical Electrical Engineering Magazine, pg 1861-1887 . Printed GB, 1931