Laying long-distance submarine telegraph cables:

4.12: Mother Earth Mother Board: As of 1861, some 17,500 kilometers of submarine cable had been laid in various places around the world, of which only about 5,000 kilometers worked. The remaining 12,500 kilometers represented a loss to their investors... long cables such as the ones between Britain and the United States and Britain and India (3,500 and 5,600 kilometers, respectively). Understanding why long cables failed was not a trivial problem....

In prospect, it probably looked like it was going to be easy. Insulated telegraph wires strung from pole to pole worked just as one might expect, and so, assuming that watertight insulation could be found, similar wires laid under the ocean should work just as well. The insulation was soon found in the form of gutta-percha.... But when immersed in water they worked poorly, if at all.

The problem was that water, unlike air, is an electrical conductor.... When a pulse of electrons moves down an immersed cable, it repels electrons in the surrounding seawater, creating a positively charged pulse in the water outside. These two charged regions interact... smear out the original pulse.... The operator at the receiving end sees only a slow upward trend in electrical charge, instead of a crisp jump.... Long cables act as antennae, picking up all kinds of stray currents... the weak, smeared-out pulses making their way down the cable would have been almost impossible to hear above the music of the spheres. Finally, leakage in the cable's primitive insulation was inevitable. All of these influences, added together, meant that early telegraphers could send anything they wanted into the big wire, but the only thing that showed up at the other end was noise....

These problems were known, but poorly understood, in the mid-1850s when the first transatlantic cable was being planned.... The Victorian era was an age of superlatives and larger-than-life characters, and as far as that goes, Dr. Wildman Whitehouse fit right in: what Victoria was to monarchs, Dickens to novelists, Burton to explorers, Robert E. Lee to generals, Dr. Wildman Whitehouse was to a--holes.... Dr. Edward Orange Wildman Whitehouse fancied himself something of an expert on electricity. His rival was William Thomson, 10 years younger... infatuated with Fourier analysis....

Wildman Whitehouse predicted that sending bits down long undersea cables was going to be easy (the degradation of the signal would be proportional to the length of the cable) and William Thomson predicted that it was going to be hard (proportional to the length of the cable squared).... The two men got into a public argument, which became extremely important in 1858 when the Atlantic Telegraph Company laid such a cable from Ireland to Newfoundland: a copper core sheathed in gutta-percha and wrapped in iron wires.

This cable was, to put it mildly, a bad idea, given the state of cable science and technology at the time. The notion of copper... it was impossible to obtain the metal in anything like a pure form. The cable was slapped together so shoddily that in some places the core could be seen poking out through its gutta-percha insulation even before it was loaded onto the cable-laying ship. But venture capitalists back then were a more rugged - not to say crazy - breed.... Let's just say that after lots of excitement, they put a cable in place between Ireland and Newfoundland. But for all of the reasons mentioned earlier, it hardly worked at all. Queen Victoria managed to send President Buchanan a celebratory message, but it took a whole day to send it.... Whitehouse convinced himself that the solution to their troubles was brute force - send the message at extremely high voltages... he soon managed to blast a hole through the gutta-percha somewhere between there and Newfoundland, turning the entire system into useless junk....

Thomson's solution (actually, the first of several solutions) was the mirror galvanometer, which incorporated a tiny fleck of reflective material that would twist back and forth in the magnetic field created by the current in the wire. A beam of light reflecting from the fleck would swing back and forth like a searchlight.... An observer with good eyesight sitting in a darkened room could tell which way the current was flowing by watching which way the spot moved.... Thomson ended up being knighted and later elevated to a baron by Queen Victoria. He became Lord Kelvin and eventually got an important unit of measurement, an even more important law of physics, and a refrigerator named after him.

Eight years after Whitehouse fried the first, a second transatlantic cable was built to Lord Kelvin's specifications with his patented mirror galvanometers at either end of it. He bought a 126-ton schooner yacht with the stupendous amount of money he made from his numerous cable-related patents, turned the ship into a floating luxury palace and laboratory for the invention of even more fantastically lucrative patents. He then spent the rest of his life tooling around the British Isles, Bay of Biscay, and western Mediterranean, frequently hosting Dukes and continental savants who all commented on the nerd-lord's tendency to stop in the middle of polite conversation to scrawl out long skeins of equations on whatever piece of paper happened to be handy.

Kelvin went on to design and patent other devices for extracting bits from the ends of cables, and other engineers went to work on the problem, too. By the 1920s, the chore of translating electrical pulses into letters had been largely automated. Now, of course, humans are completely out of the loop.

The number of people working in cable landing stations is probably about the same as it was in Kelvin's day. But now they are merely caretakers for machines that process bits about as fast as a billion telegraphers working in parallel...