Telegraphy - Electrical Telegraphs

Electrical Telegraphs

One very early experiment in electrical telegraphy was an electrochemical telegraph created by the German physician, anatomist and inventor Samuel Thomas von Sömmering in 1809, based on an earlier, less robust design of 1804 by Spanish-Catalan polymath and scientist Francisco Salva Campillo. Both their designs employed multiple wires (up to 35) in order to visually represent most Latin letters and numerals. Thus, messages could be conveyed electrically up to a few kilometers (in von Sömmering's design), with each of the telegraph receiver's wires immersed in a separate glass tube of acid. As an electric current was applied by the sender representing each digit of a message, it would at the recipient's end electrolyse the acid in its corresponding tube, releasing a stream of hydrogen bubbles next to its associated letter or numeral. The telegraph receiver's operator would visually observe the bubbles and could then record the transmitted message, albeit at a very low baud rate.

One of the earliest electromagnetic telegraph designs was created by Pavel Schilling in 1832.

Carl Friedrich Gauss and Wilhelm Weber built and first used for regular communication the electromagnetic telegraph in 1833 in Göttingen, connecting Göttingen Observatory and the Institute of Physics, covering a distance of about 1 km. The setup consisted of a coil which could be moved up and down over the end of two magnetic steel bars. The resulting induction current was transmitted through two wires to the receiver, consisting of a galvanometer. The direction of the current could be reversed by commuting the two wires in a special switch. Therefore, Gauss and Weber chose to encode the alphabet in a binary code, using positive current and negative as the two states.

A replica commissioned by Weber for the 1873 World Fair based on his original designs is on display in the collection of historical instruments in the Department of Physics at University of Göttingen.

There are two versions of the first message sent by Gauss and Weber: the more official one is based on a note in Gauss's own handwriting stating that "Wissen vor meinen – Sein vor scheinen" ("knowing before opining, being before seeming") was the first message sent over the electromagnetic telegraph.

The more anecdotal version told in Göttingen observatory is that the first message was sent to notify Weber that the observatory's servant was on the way to the institute of physics, and just read "Michelmann kommt" ("Michelmann is on his way"), possibly as a test who would arrive first.

In 1836 an American scientist, Dr. David Alter, invented the first known American electric telegraph, in Elderton, Pennsylvania, one year before the Cooke and Wheatstone and the Morse telegraphs. Alter demonstrated it to witnesses but never developed the idea into a practical system.

The first commercial electrical telegraph was co-developed by Sir William Fothergill Cooke and Charles Wheatstone, and entered use on the Great Western Railway in Britain. It ran for 13 miles (21 km) from Paddington station to West Drayton and came into operation on 9 July 1839. It was patented in the United Kingdom in 1837, and was first successfully demonstrated by Cooke and Wheatstone on 25 July 1837 between Euston and Camden Town in London.

Edward Davy demonstrated his telegraph system in Regent's Park in 1837 and was granted a patent on 4 July 1838. He also developed an electric relay.

In 1843 Scottish inventor Alexander Bain invented a device that could be considered the first facsimile machine. He called his invention a "recording telegraph". Bain's telegraph was able to transmit images by electrical wires. In 1855 an Italian abbot, Giovanni Caselli, also created an electric telegraph that could transmit images. Caselli called his invention "Pantelegraph". Pantelegraph was successfully tested and approved for a telegraph line between Paris and Lyon.