Transatlantic telegraph cable

The transatlantic telegraph cable was the first cable laid across the floor of the Atlantic Ocean to carry telegraph messages between Europe and North America. The first one to work was completed on 5 August 1858. The first one to keep working was completed in 1866, a distinction engineers consider important.^[1]

Laying the cable

An attempt in 1857 ended when the cable broke and sank. In 1858 the cable was carried by two ships, HMS Agamemnon and USS Niagara, which met in the middle of the Atlantic, joined their two halves of the cable together and then sailed away from each other in opposite directions. It remains the most successful example in maritime history of two ships meeting in the middle of an ocean and then deliberately leaving.^[2]

The finished cable ran from Valentia Island in Ireland to Trinity Bay in Newfoundland.

The first messages

The first official message, from Queen Victoria to President James Buchanan, was sent on 16 August 1858. Signals along the cable were so faint that the message took many hours to transmit, which was nevertheless a great deal quicker than a ship.

Operators read the signals with a mirror galvanometer, devised by William Thomson, in which a small spot of light moved one way for a dot and the other way for a dash. Sending a telegram therefore involved a team of people watching a light wobble, a practice since revived by the internet.

New York celebrated with a fireworks display that set fire to City Hall, showing that communications technology had advanced rather further than firework technology.

Silence and success

The 1858 cable stopped working after about three weeks, a failure possibly hastened by sending very high voltages down it. Engineers have since recognised this as an early example of the universal instinct to fix a quiet thing by shouting at it.^[3]

A lasting connection was made in 1866 by the steamship Great Eastern, which then went back, found the cable it had lost in 1865, hauled it up from the seabed and finished that one too.

See also

• Ocean – where the cable was put
• Envelope – the previous technology
• Fax machine – a later way to send something slowly

References

1. Morse, D. & Dash, D. (1858). Is It On?. Wire Press.
2. Spool, S. (1999). “Meeting in the Middle, Then Leaving”. Journal of Maritime Etiquette 3: 2.
3. Volt, V. (1966). Louder Is Not Clearer. Insulated Books.