Transatlantic telegraph :
A transatlantic telegraph cable is an undersea cable running under the Atlantic Ocean used for telegraph communications. The first was laid across the floor of the Atlantic from Telegraph Field, Foilhommerum Bay, Valentia Island in western Ireland to Heart’s Content in eastern Newfoundland. The first communications occurred August 16, 1858, reducing the communication time between North America and Europe from ten days – the time it took to deliver a message by ship to a matter of minutes.
History:
Cyrus West Field and the Atlantic Telegraph Company were behind the construction of the first transatlantic telegraph cable. The project began in 1854 and was completed in 1858. The cable functioned for only three weeks, but it was the first such project to yield practical results. Signal quality declined rapidly, slowing transmission to an almost unusable speed. The cable was destroyed the following month when Wildman Whitehouse applied excessive voltage to it while trying to achieve faster operation. It has been argued that the faulty manufacture, storage and handling of the 1858 cable would have led to premature failure. The telegraph cable’s rapid failure undermined public and investor confidence and delayed efforts to restore a connection. A second attempt was undertaken in 1865 with much-improved material and, following some setbacks, a connection was completed and put into service on July 28, 1866.
Previously, telegraph communications between Europe and the Americas could only happen by ships which were, on occasion, delayed for weeks due to severe winter storms. The transatlantic cable reduced communication time considerably, allowing a message and a response in the same day. Five attempts to lay a cable were made over a nine-year period – one in 1857, two in 1858, one in 1865, and one in 1866. Lasting connections were finally achieved with the 1866 cable and the 1865 cable, which was repaired by Isambard Kingdom Brunel’s ship the SS Great Eastern, captained by Sir James Anderson.In the 1870s duplex and quadruplex transmission and receiving systems were set up that could relay multiple messages over the cable. Additional telegraph cables were laid between Foilhommerum and Heart’s Content in 1873, 1874, 1880, and 1894. By the end of the 19th century, British-, French-, German-, and American-owned cables linked Europe and North America in a sophisticated web of telegraphic communications.
SS Great Eastern:
The SS Great Eastern was an iron sailing steam ship designed by Isambard Kingdom Brunel, and built by J. Scott Russell & Co. at Millwall on the River Thames, London. She was by far the largest ship ever built at the time of her 1858 launch, and had the capacity to carry 4,000 passengers around the world without refueling. Her length of 692 feet (211 m) was only surpassed in 1899, and her gross tonnage of 18,915 was only surpassed in 1901. With five funnels (later reduced to four), she was one of a very few vessels to ever sport that number, sharing her number of five with the Russian cruiser Askold though several warships, including HMS Viking, and several French cruisers of the pre-dreadnought era had six.
During Great Eastern’s maiden voyage, in which she was damaged by an explosion. After repairs, she plied for several years as a passenger liner between Britain and America before being converted to a cable-laying ship and laying the first lasting transatlantic telegraph cable in 1866. The conversion work for Great Eastern’s new role consisted in the removal of funnel no. 4 and some boilers as well as great parts of the passenger rooms and saloons to give way for open top tanks for taking up the coiled cable. Under Sir James Anderson she laid 4,200 kilometers (2,600 mi) of the 1865 transatlantic telegraph cable. Under Captains Anderson and then Robert Halpin, from 1866 to 1878 the ship laid over 48,000 kilometers (30,000 mi) of submarine telegraph cable including from Brest, France to Saint Pierre and Miquelon in 1869, and from Aden to Bombay in 1869 and 1870.
Communication speeds:
Initially messages were sent by an operator sending Morse code. The reception was very bad on the 1858 cable, and it took two minutes to transmit just one character (a single letter or a single number), a rate of about 0.1 words per minute. This is despite the use of a highly sensitive mirror galvanometer, a new invention of the time.
The first telegraph message on the 1858 cable took over 17 hours to transmit. For the 1866 cable, the methods of cable manufacture, as well as sending messages, had been vastly improved. The 1866 cable could transmit eight words a minute – 80 times faster than the 1858 cable. Heaviside and Mihajlo Idvorski Pupin in later decades understood that the bandwidth of a cable is hindered by an imbalance between capacitive and inductive reactance, which causes a severe dispersion and hence a signal distortion. This has to be solved by iron tape or by load coils. It was not until the 20th century that message transmission speeds over transatlantic cables would reach even 120 words per minute. Despite this, London had become the world center in telecommunications. Eventually, no fewer than eleven cables radiated from Porthcurno Cable Station near Land’s End and formed with their Commonwealth links a “live” girdle around the world.
Sources/References:
- http://exhibits.library.
villanova.edu/lane/telegraph - http://www.oldog.co.uk/
TransatlanticCable/ TransatlanticCable.htm - http://en.wikipedia.org/wiki/Transatlantic_telegraph_cable
