Upvote:2
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.