I once watched a wonderful documentary about the history of long distance communication but have since forgotten its title, where I saw it, and how to find it again.

I really only remember two pieces of the documentary, which is why I want to find it and watch it again!

The first thing I remember is that the documentary began by discussing communication via a clepsydra (for which I found the following description from here).

Another queer signaling device, built and operated upon a novel principle, was an even greater wonder among the early peoples. This was known as a clepsydra. Fancy a tall glass tube with an opening at the bottom in which a sort of faucet was fixed. At varying heights sentences were inscribed about the tube. The tube, being filled with water, with, a float at the top, all was ready for signaling any of the messages inscribed on the tube to a station within sight and similarly equipped. The other station could be located as far away as a light could be seen. The station desiring to send a message to another exhibited its light. When the receiving station showed its light in answer, the tap was opened at the bottom of the tube in each station. When the float dropped until it was opposite the sentence which it was desired to transmit, the sending station withdrew its light and closed the tap. This was a signal for the receiving station to stop the flow of water from its tube. As the tubes were just alike, and the water had flowed out during the same period at equal speed, the float at the receiving station then rested opposite the message to be conveyed.

The other thing that I remember from the documentary was presented somewhat later. It was about the telegraph and the laying of the first transatlantic line. If I remember correctly, it said the first cable broke while being laid, but the laying of the second cable was successful (the first user being the monarch of England and, probably, the U.S. president). Later, this cable stopped working and another one was laid.

It would be great if someone knows what documentary I am talking about so I can both watch it again and share it with others.

  • I'm pretty sure you can manage to give some more detail about where you watched it. Anything may help: year "more or less", nation where you watched it, "air, cable, satellite vhs, etc."
    – o0'.
    Dec 12, 2011 at 15:58
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    Have you tried imbd search? I do not know if they have documentaries or not. Alternatively, do you remember who narrated it? Dec 12, 2011 at 16:10
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    @Lohoris I watched it in the US. Maybe I watched it five years ago. I mostly likely watched it through cable. Dec 12, 2011 at 23:15
  • @Sardathrion Appears like they only have movies. Dec 12, 2011 at 23:17
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    Do you have any more on this like was it one documentary? Do you remember the channel? It's hard to find a documentary unless it's listed somewhere with the right metadata.
    – MichaelF
    Dec 14, 2011 at 16:57

1 Answer 1


American Experience (on PBS) aired a documentary called The Great Transatlantic Cable many years back. I don't remember any mention of the clepsydra, but the story of the first cable burning out after just a few weeks in most assuredly in there. Basically, the engineers had assumed that you needed to push a lot of current through the wire, when in fact, just a little current would work just as well...

I also seem to remember the first attempt was harder because the cable would not fit on a single ship, and thus it had to be spliced together on board. For the second laying, the world's largest ship ever was repurposed to hold the cable.

  • Around the same time though, I seem to remember a documentary talking about the history of long distance communication where the French would station semaphores - people waving flags - to transmit messages. Maybe that might be a lead? Dec 15, 2011 at 20:25
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    While this, the best answer, receives the bounty, I am still interested in an explicit reference. Dec 19, 2011 at 15:49
  • Uh? Can't you just, you know, watch it and discover if it is the correct one or not?
    – o0'.
    Jan 16, 2012 at 17:35

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