Optic to Electric to Optic

Preliminary Steps

On the Origin and Progress of the Oceanic Electric Telegraph As early as 1845, John Brett had proposed laying a cable across the Atlantic. By 1858 he had joined the American promoter Cyrus Field on the team that made the proposal a reality. This volume is a special presentation copy given to physicist William Thomson, another key player in the creation of underwater cables.
John Brett, On the Origin and Progress of the Oceanic Electric Telegraph (London, 1858)
Smithsonian Institution Libraries

In addition to the invention of the telegraph itself, three technical developments in the 1840s had to occur before underwater cables became possible:


  1. Insulation: Europeans "discovered" gutta percha. This waterproof insulating material from Malaysia could cover long lengths of wire.
    gutta percha
    It may not look like much, but gutta percha was the miracle substance of the Victorian age. It could be molded into any shape, and was used in everything from electric wiring to jewelry to golf balls.

    Gutta percha (above)
    National Museum of American History
    Harvesting gutta percha Gutta percha is a natural plastic, similar to rubber, that comes from the sap of trees in Southeast Asia. Local populations had long used it, but the West "discovered" it in the 1840s. When warmed, gutta percha was soft enough to be extruded easily around a copper wire. In deep water, the cold and pressure hardened it and improved its insulating qualities. The cables used massive amounts of gutta percha; thousands of acres of trees were destroyed before a plantation system was established in the late 1800s.
    Harvesting gutta percha
    From Th. Seeligmann, Indiarubber and Gutta Percha, 1903


    Indiarubber and Gutta Percha: A Complete Practical Treatise
    Th. Seeligmann, G. Lamy Torrilhon, and H. Falconnet, Indiarubber and Gutta Percha: A Complete Practical Treatise (London, 1903)
    Smithsonian Institution Libraries


  2. Protection: Woven iron wires, a technique invented by the shipbuilding industry, gave cables a sturdy armor.
    Weaving iron wire around a cable
    Weaving iron wire around a cable
    From Charles Bright, Submarine Telegraphs, 1898
    Smithsonian Institution Libraries


  3. Transportation: Steamships became larger and more powerful, able to carry miles of heavy cable and lay it in a straight line.
    Laying cable in the English Channel, 1850 Cable-laying operations posed risks, even for short distances. The heavy cable was often loaded on deck, upsetting the ship's balance. It had to be paid out at a steady rate - no easy task on a rocking ship - so that it would lie evenly on the bottom. The jerking movement of rough seas or the sheer weight of the cable hanging overboard could cause it to snap.
    Laying cable in the English Channel, 1850
    From Charles Bright, Submarine Telegraphs, 1898
    Smithsonian Institution Libraries



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