We now take wires and cables for granted. In the early nineteenth century, plastics hadn't been invented and the only material available for insulation and waterproofing was asphaltum – a type of pitch. In 1843 a form of rubber called gutta percha was discovered and used to insulate the signal-carrying path in cables. The Atlantic Telegraph Company created an insulated cable for underwater use containing a single copper conductor made of seven twisted strands, surrounded by gutta percha insulation and protected by a ring of 18 iron wires coated with hemp and tar. 

Submarine cable telegraphy began with a cable crossing the English Channel to France in 1850. The cable failed after only a few messages had been exchanged and a more successful attempt was made the following year.

Transatlantic cable laying from Ireland began in 1857 but was abandoned when the strain of the cable descending to the ocean bottom caused it to snap under its own weight. The Atlantic Telegraph Company tried again in 1858. Again, the cable broke after only three miles but the two cable-laying ships managed to splice the two ends. The cable eventually reached Newfoundland in August 1858 after suffering several more breaks and storm damage. 

It soon became clear that this cable wasn't going to be a commercial success. The receiver used the magnetic field from current in the cable to deflect a magnetized needle. Unfortunately, after crossing the Atlantic the signal was too weak to be reliably detected. The original voltage used to drive a current down the cable was approximately 600 volts. So, they raised the voltage to about 2,000 V to drive more current along the cable and improve the detection process. Unfortunately, such a high voltage burned through the primitive insulation, shorted the cable, and destroyed the first transatlantic telegraph link after about 700 messages had been transmitted in three months. 

In England, the Telegraph Construction and Maintenance Company developed a new 2300-mile long cable weighing 9,000 tons that was three times the diameter of the failed 1858 cable. Laying this cable required the largest ship in the world, the Great Eastern (Figure 2.5). After a failed attempt in 1865 a transatlantic link was finally established in 1866. It cost $100 in gold to transmit 20 words (including the address) across the first transatlantic cable at a time when a laborer earned $20/month. 

 The Great Eastern cable-laying ship